Trends in the Distribution, Abundance,
j&&-- ^ J- ~~
and Habitat Quality of Submerged
^ ^*f-
Aquatic Vegetation in Chesapeake
Bay and its Tidal Tribi
1971 to 1991
:"'
"Hi.
1978 1964 1985 1986 1987 1989 1990 1991
lesapeake Bay Program
O Recycled/Recyclable
Ay Pnnted with soy/canola ink on paper that
contains at least SO^r recycled fiber.
CBP/TRS 137/95
EPA903-R-95-009
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CHESAPEAKE BAY PROGRAM
Living Resources Subcommittee
Chair: Carolyn V. Watson
Director, Regional Chesapeake Bay Program
Maryland Department of Natural Resources
Tawes State Office Building
Annapolis, MD 21401
(410)974-2255
Coordinator: Carin Bis/and
Environmental Protection Agency
Chesapeake Bay Program Office
410 Severn Avenue, Suite 109
Annapolis, MD 21403
(410)267-5732
MEMORANDUM
To:
Implementation Committee Members
Data Analysis Workgroup
Living Resources Subcommittee
Living Resources Monitoring Workgroup
Living Resources Workgroup Chairs
Monitoring Subcommittee Members and Interested Parties
Submerged Aquatic Vegetation Workgroup
NutjJel^R/sevaluation Workgroup
From: Gafeiyif^TWatson, Chair, Living Resources Subcommittee
Date: October 10, 1995
Re: Submerged Aquatic Vegetation (SAV) Trends Report .
Enclosed is a copy of the report entitled: Trends in the Distribution, Abundance, and
Habitat Quality of Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries:
1971 to 1991. This report presents results from a research project funded through the Living
Resources Subcommittee (LRSc) Bay Program budget. It has been reviewed and accepted by
members of the SAV Technical Workgroup.
I am pleased to submit this final report to you. If you need additional copies, please
contact Katrin O'Connell at: (410) 267-5719.
CCT ? 2
Enclosure
CVW/kro
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Trends in the
Distribution, Abundance,
and Habitat Quality of
Submerged Aquatic Vegetation
in Chesapeake Bay
and its Tidal Tributaries:
1971 to 1991
Robert J. Orth1
Richard A. Batiuk2
Judith F. Nowak1
Annapolis, Maryland
May, 1994
Printed by the United States Environmental Protection Agency
for the Chesapeake Bay Program
Recycled/Recyclable
Printed with soy/canola ink on paper that
contains at least 50% recycled fiber.
1 School of Marine Science; Virginia Institute of Marine Science; College of William and Mary; Gloucester Point, VA 23062
2 U.S. Environmental Protection Agency; Chesapeake Bay Program Office; Annapolis, MD 21403
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Executive Summary
Over the last three to four decades, declines of many Chesapeake Bay species from overharvesting,
deterioration of water quality, habitat destruction, disease, and meteorological changes have alarmed
scientists, managers, politicians, and the public. This concern has prompted scientists to study the
magnitude and causes of the declines and managers to develop basinwide agreements to protect, restore,
and enhance these living resources.
Submerged aquatic vegetation (SAV) historically contributed to the high primary and secondary
productivity of Chesapeake Bay, but in the late 1960s and 1970s it experienced a dramatic baywide
decline due to increased nutrient and sediment inputs from development of the surrounding watershed.
This decline galvanized diverse groups into formulating the Submerged Aquatic Vegetation Policy for
the Chesapeake Bay and Tidal Tributaries and the Implementation Plan for the Submerged Aquatic
Vegetation Policy that would guide managers and scientists in SAV assessment, protection, education,
and research to ensure the restoration of these plants.
Living resources monitoring programs are critical in understanding fluctuations in resource
abundance. In Chesapeake Bay, monitoring SAV is used to evaluate the success of restoration and
protection efforts. The strong link between water quality and the distribution and abundance of SAV
makes these plants a good barometer of Chesapeake Bay health.
Significant progress has been made in defining habitat requirements for SAV in Chesapeake Bay.
Linked with achievement of these SAV habitat requirements is a tiered set of SAV distribution restoration
goals and targets established for Chesapeake Bay, along with restoration targets for SAV bed density
and species diversity.
This report builds on two decades of aerial and ground survey SAV distribution data, as well as
development of SAV habitat requirements, establishment of SAV restoration goals and targets, com-
pilation of historical water quality data, and implementation of a baywide monitoring program. The
objectives of this report are to:
• describe trends in SAV distribution and abundance in Chesapeake Bay and its tidal tributaries
from 1971 to 1991;
• relate SAV distribution over time with tiered distribution restoration goals and targets;
• compare trends in SAV distribution with corresponding trends in water quality; and
• correlate SAV distribution with river flow.
Since the first baywide SAV survey in 1978, the total abundance of SAV in Chesapeake Bay and
its tidal tributaries has increased by 52 percent from 16,895 hectares in 1978 to 25,623 hectares in 1991
(Figure I, Table I). The 1991 data represent a 56 percent achievement of the Tier I SAV distribution
restoration goal (46,025 hectares) and a 10 percent achievement of the Tier III SAV distribution
restoration target (247,658 hectares).
Along with the increase in SAV distribution between 1984 and 1991 was a concomitant increase
in the overall density of many SAV beds. While 38 percent (5,931 hectares) of mapped SAV was
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Executive Summary
25000 ~
20000 ~
§
•g 15000
CO
2>
SB 10000
o
m
5000-
ND ND ND ND ND
79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData
70-100%
40-70% £2 10-40%
No Density Reported
Figure I. Hectares of SAV by density category for all years for which aerial survey data were available baywide. The baywide
Tier I SAV restoration goal and Tier III SAV restoration target are 46,025 and 247,658 hectares, respectively. In 1978,
density was not recorded for the SAV mapped in the Maryland portion of Chesapeake Bay.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al., 1979, 1985, 1986, 1987, 1989, 1991, and
1992; Orth and Nowak, 1990.
classified as dense (70-100 percent coverage) in 1984, by 1991 more than twice as many hectares of
SAV (12,947 hectares or 50 percent of the total) fit this category (Figure I, Table I).
Patterns of change in SAV populations throughout Chesapeake Bay were complex and varied both
in space and time. This complexity most likely reflects the differing characteristics of the Bay's major
watersheds, meteorological differences, and differences in the biology of the SAV species. To further
describe bay wide trends, patterns of SAV distribution from 1984 to 1991 (and from 1971 to 1991 when
data were available) in all Chesapeake Bay Program segments were characterized and assigned to one
of the following five categories: increasing trend, fluctuating at high levels, fluctuating at low levels,
decreasing trend, and little or no SAV (Figure II).
Consistent annual increases in SAV distribution and abundance since 1978 occurred in seven of
the 45 Chesapeake Bay Program segments (Lower Chesapeake Bay (CBS); Western Lower Chesapeake
Bay (CB6); Eastern Lower Chesapeake Bay (CB7); Tangier Sound (EE3); Mobjack Bay (WE4); Middle
Potomac River (RET2); and Upper Potomac River (TF2)) (Figure III). Five of the segments are
contiguous in the middle to lower portion of the mainstemBay (Lower Chesapeake Bay, Western Lower
Chesapeake Bay, Eastern Lower Chesapeake Bay, Tangier Sound, and Mobjack Bay) and are areas where
relatively large, viable populations of SAV still remained after the 1970s decline. Percent increases
in SAV distribution from 1978 to 1991 were 56 percent in Mobjack Bay, 64 percent in Eastern Lower
Chesapeake Bay, 85 percent in Western Lower Chesapeake Bay, 127 percent in Lower Chesapeake
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
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Executive Summary
Table 1. Hectares of SAV by Density Category for all Years for which Aerial Survey Data were Available Baywide
Year No Density <10% 10-40% 40-70% 70-100% Baywide
Reported Total
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
ND = No Data
8360
ND
ND
ND
ND
ND
—
—
—
—
ND
—
—
—
Sources: Anderson and Macomber,
and1992;0rth
andNowak, 1990.
911
ND
ND
ND
ND
ND
2,787
3,227
3,785
3,640
ND
3,331
3,561
3,199
1980;
2,387
ND
ND
ND
ND
ND
2,861
4,111
3,596
3,296
ND
4,350
5,603
4,851
Batiuketal., 1992;0rthetal.,
4,229
ND
ND
ND
ND
ND
3,854
6,500
3,761
3,585
ND
3,730
3,990
4,731
1979, 1985,
1,011
ND
ND
ND
ND
ND
5,931
6,135
8,283
9,713
ND
12,836
11,240
12,947
1986, 1987, 1989,
16,898
. ND
ND
ND
ND
ND
15,433
19,974
19,425
20,234
ND
24,247
24,394
25,728
1990, 1991,
Bay, and 232 percent in Tangier Sound. The larger increases in the Lower Chesapeake Bay and Tangier
Sound segments were due primarily to the rapid and sudden growth of Ruppia maritima in the Barren
Island-Honga River area. These areas had almost no SAV in 1978 but by 1984, SAV beds were reported
throughout the area. These beds increased rapidly into large, monospecific, and dense populations of
R. maritima.
Water quality conditions in the lower mainstem Bay, Tangier Sound, and Mobjack Bay have been
suitable for SAV survival and growth consistently since the early 1980s. Up through the late 1970s,
the data indicate water quality conditions in these segments fluctuated between unsuitable (not meeting
SAV habitat requirements) and suitable (meeting SAV habitat requirements) on an annual basis. The
improvements in water quality—relative to the SAV habitat requirements—correspond with documented
increases in SAV distribution and abundance.
The upper (TF2) and middle (RET2) segments of the Potomac River were the only other areas
showing consistently increasing trends in SAV distribution. These increases resulted, in part, from the
1982 introduction ofHydrilla verticillata and its subsequent rapid spread along more than 60 kilometers
of shoreline in less than ten years. In the upper and middle reaches of the Potomac River, water quality
conditions just met or were slightly above several of the SAV habitat requirements until 1991.
Concentrations of the SAV habitat requirement parameters decreased over the water quality data record
from 1970 to 1991.
Seven of the Chesapeake Bay Program segments were classified as areas in which SAV occurred
in areas greater than 100 hectares but showed no consistent trend of either increasing or decreasing
acreage: Northern Chesapeake Bay (CB1); Eastern Bay (EE1); and the Elk/Bohemia (ET2), Lower
Choptank (EE2), Manokin (ET8), Big Annemessex (ET9), and the Lower Rappahannock (LE3) river
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Executive Summary
ET1
ii_j Increasing Trends
lililil Fluctuating at Higher Levels
Fluctuating at Lower Levels vra
Decreasing Trends
Little or No SAV
WT1
WT2
WT3
TF2
RET2
ET7
ET10
EE3
CB7
TF5
CB8
Figure II. Patterns of SAV distributions from 1971-1991 by Chesapeake Bay Program segment.
Sources: Anderson and Macomber, 1980; Chesapeake Bay Program, unpublished data b; Orth et al., 1979,1985,1986,
1987,1989,1991, and 1992; Orth and Gordon, 1975; Orth and Nowak, 1990.
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Executive Summary
Upper Potomac River
Tangier Sound
B »M% Q »m Q I
Eastern Lower Chesapeake Bay
«»«»»i»iii»uirjii)»uiiiai«iii
D |»» D •»» D »•* I
Western Lower Chesapeake Bay
ic to m> to m »
(3 »m Q «MW. D <
Figure III. Chesapeake Bay segments with increasing trends in SAV.
Sources: Anderson and Macomber, 1980; Chesapeake Bay Program, unpublished data b; Orth et al., 1979,1985,1986,
1987,1989,1991, and 1992; Orth and Gordon, 1975; Orth and Nowak, 1990.
Trends in the Distribution, Abundance, and Habitat Quality of
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Executive Summary
segments (Figure IV). Three of these segments (the Manokin, Big Annemessex, and Lower Rappah-
annock rivers) were located near or adjacent to those segments showing consistent increases in SAV
distribution. In two segments (Eastern Bay and Lower Choptank River), R. maritima rapidly expanded
in the mid-1980s but had begun to decline by 1990. By 1991, this species made up only a few scattered
beds.
The Susquehanna Flats and tidal Susquehanna River (the northern Chesapeake Bay segment) are
included in this category. Interestingly, the flanks of the tidal Susquehanna River below Conowingo
Dan are densely vegetated with several SAV species. The very large shallow-water area (Susquehanna
Flats), which historically supported one of the Bay's largest SAV communities and contained numerous
SAV species, remains sparsely vegetated with only Myriophyllum spicatum.
In four segmen :s with SAV distributions fluctuating at higher levels (Northern Chesapeake Bay,
Eas :ern Bay, Lower Choptank River, and Lower Rappahannock River), water quality conditions often
just meet SAV habitat requirements. In the three Eastern Shore tributary segments in this category (the
ElkyBohemia, Manolcin, and Big Annemessex rivers) both the light attenuation coefficient and total
suspended solids habitat requirements have generally not been met from 1970 to 1991.
Nine of the Chesapeake Bay Program segments were classified as areas where SAV occurred in
distributions under 100 hectares but showed no consistent trend of either increasing or decreasing SAV
distribution (the Upper Chesapeake Bay (CB2); Middle Central Chesapeake Bay (CB4); Mouth of
Chesapeake Bay (CBS); and the Sassafras (ET3), Gunpowder (WT2), Middle (WT3), Lower Patuxent
(LEI), Lower Potomac (LE2), and Lower York (LE4) river segments) (Figure V). Similar to those
segments in which SAV fluctuates at higher levels, most of these segments were either part of the
mainstem Bay or we:-e immediately adjacent to it. This group included the Lower York River segment
where SAV is preser t in a very small section near the river mouth; the Lower Potomac River segment
where SAV is absent from almost all of the mainstem river; the lower Patuxent River segment; the
only two western she re tributaries (the Gunpowder and Middle rivers) that have consistently supported
SAV populations throughout the 1980s and 1990s; and three mainstem Bay segments (Upper Chesapeake
Bay, Middle Central Chesapeake Bay, and Mouth of the Chesapeake Bay) that contain few areas that
cou d support SAV due to exposed shorelines.
Segments with SAV distributions fluctuating at low levels have had either: water quality conditions
suitable for SAV survival and growth but with limited potential habitat (Middle Central Chesapeake
Bay and Mouth of Ch ssapeake Bay); water quality conditions generally suitable for SAV but with limited
sources of the propagules necessary for restoration (Lower Patuxent and Lower Potomac rivers); or
water quality conditions which ranged from unsuitable to suitable for SAV survival and growth from
1971 to 1991 (the Upper Chesapeake Bay and the Sassafras, Gunpowder, Middle, and Lower York
rivers).
Only two of the 45 Chesapeake Bay Program segments were classified as areas with consistently
decreasing trends in SAV distribution (Upper Central Chesapeake Bay (CBS) and Chester River (ET4)
segments) (Figure VI). These two segments were flanked by segments with little or no SAV (Back,
Patapsco, and Magothy rivers) and those with SAV fluctuating at low abundance levels (Upper
Chesapeake Bay, Middle Central Chesapeake Bay, Gunpowder River, and Middle River). The Upper
Central Chesapeake Bay and Chester River historically supported some of the largest concentrations
of SAV beds with high species diversity in the middle Chesapeake Bay region—particularly adjacent
to E.astern Neck and Eastern Neck Island.
vi Trends in the Distribution, Abundance, and Habit?* Duality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Executive Summary
Northern Chesapeake Bay
Elk/Bohemia Rivers
Figure IV. Chesapeake Bay segments with SAV fluctuating at higher levels of abundance.
Sources: Anderson and Macomber, 1980; Chesapeake Bay Program, unpublished data b; Orth et al., 1979,1985,1986,
1987,1989,1991, and 1992; Orth and Gordon, 1975; Orth and Nowak, 1990.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
VII
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Executive Summary
Gunpowder River
Sassafras River
Middle Central Chesapeake Bay
Figure V. Chesapeake Bay segments with SAV fluctuating at lower levels of abundance.
Sources: Anderson anc Macomber, 1980; Chesapeake Bay Program, unpublished data b; Orth et al., 1979,1985,1986,
1987,1989, 1991, and 1992; Orth and Gordon, 1975; Orth and Nowak, 1990.
VIII
Trends in the Distribution, Abundan^, ..nd Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
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Executive Summary
Upper Central Chesapeake Bay
Chester River
D »«* D «w» Q I
Figure VI. Chesapeake Bay segments with decreasing trends.
Sources: Anderson and Macomber, 1980; Orth et al., 1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Executive Summary
Water quality conditions meeting the SAV habitat requirements in the Upper Central Chesapeake
Bay f uctuated from year to year over the 1971 to 1991 data record. Water quality in the adjacent Chester
River has generally been unsuitable for SAV survival since the mid 1970s.
Twenty of the segments have had little SAV (less than 50 hectares)—Northeast (ET1), (Bush
(WT1), Patapsco (WT:5), Magothy (WT6), Severn (WT7), South/Rhode/West (WT8), Choptank.(ET5),
Upper Patuxent (TF1), Middle Patuxent (RET1), Middle James (RETS), and Lower James (LE5) rivers
(Figure VII)—or no !>AV present since 1978—Back (WT4), Upper Rappahannock (TF3), Middle
Rappahannock (RET3), Upper York (TF4), Middle York (RET4), Upper James (TF5), Nanticoke (ET6),
Wiccmico (ET7), and Pocomoke (ET10) river. All of the major western shore tributaries, except the
Potomac River, had two or all three segments in this category. The upper tidal fresh and middle transition
segments of these rivers were largely unvegetated. All other segments having little or no SAV are the
smaller tributaries alcng the western or eastern shore. The relatively small drainage basins of these
tributaries encompass both highly urbanized and industrialized areas (i.e., the Bush, Back, Patapsco,
Magothy, Severn, and South rivers), as well as areas with intensive agriculture (i.e., the Choptank,
Nanticoke, and Wicomico rivers) which result in greater nonpoint source inputs of nutrients and
sediments.
Ground surveys show that these smaller tidal tributaries had supported SAV beds prior to 1971.
Since 1971, however, water quality conditions have been generally unsuitable for SAV survival in these
segments where little or no SAV has been mapped.
The river flows of the Susquehanna and Potomac rivers were analyzed to evaluate whether flow
is a §;ood indicator of SAV distribution patterns over time. River flow from these two systems accounts
for approximately 75 percent of the total freshwater inflow to the Bay. River flow can integrate localized
rainfall events minimizing the bias inherent in localized rainfall patterns. The assumption made here
is that higher river flow is directly correlated with higher inputs of sediments and nutrients.
The annual river flow pattern in the Susquehanna data (Figure VIII) generally shows average flows
in the 1950s, below average flows in the 1960s (the 1962 to 1966 period was one of the lowest flow
periods in the 42-year data set), and above average flows in the 1970s. The Potomac River flow data
shov/ patterns by decade that resemble those in the Susquehanna although the differences were less
pronounced.
These river flow patterns may be a critical driving force in structuring SAV in Chesapeake Bay.
In the 1950s, SAV populations generally flourished in most sections of the Bay and its tidal tributaries;
rive: flow during the SAV growing season was normal with a couple of years of above normal runoff
punctuated by low runoff years. Submerged aquatic vegetation continued to flourish in the 1960s, a
decade characterized by below average river flow. The 1970s were years of major SAV decline bay wide
and the highest river flow. Submerged aquatic vegetation began to rebound in the 1980s as river flow
returned to normal. An interesting comparison shows that the 1980s are punctuated by both high and
low flow years. Submerged aquatic vegetation populations could potentially be sustained during high
flov/ years if their growth, distribution, and abundance are maximized during low flow years. Several
consecutive high flow years may be most detrimental to SAV populations.
In summary, the largest expansion of SAV between 1978 and 1991 occurred in the lower mainstem
Ba> segments where SAV populations had not declined as significantly during the 1970s and where
wat ;r quality consistently met the SAV habitat requirements. The SAV beds remaining in these segments
Trends in the Distribution '.1/undance, and Habitat Quality of
Sut merged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
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Executive Summary
Patapsco River
Bush River
Middle James River
Northeast River
Q »wn D »m Q I
Choptank River
• ofl.
Q »wn Q »m Q
Upper Patuxent River
B * I • «) t *
Middle Patuxent River
Q »m D «M01
Lower James River
O »m D »
NO SAV:
1. Back River
2. Upper Rappahannock River
3. Middle Rappahannock River
4. Upper York River
5. Middle York River
6. Upper James River
7. Nanticoke River
8. Wicomico River
9. Pocomoke River
Figure VII. Chesapeake Bay segments with little or no SAV.
Sources: Anderson and Macomber, 1980; Chesapeake Bay Program, unpublished data; Orth et al., 1977,1985,1986,
1987,1989, 1991, and 1992; Orth and Gordon, 1975; Orth and Nowak, 1990.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
XI
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Executive Summary
i-
in in
03r^OOOiOT-CVJC«3'5tir)COI^OOO>Or'CMCO'^-inCD
in in jnincopiDcocococDcptpcDr^t"- f»t>-!>ts-t%-
-i-
£" 5-ooco
CD co co co o> p>
Fig ire VIII. Susquehanna R ver flow presented as the number of months between April and October (the SAV growing season) within each year
from 1950 to 1991 in which 'hs mean monthly flow is above the 50th percentile (• • • • •) and the 75th percentile ( ) of total
river flow.
Souce: U.S. Geological Sur/ey.
after the baywide de:line may have contributed to a pool of propagules (i.e., seeds or fragments of
vegetation capable of forming new plants) that repopulated unvegetated areas.
The rapid spread of SAV in the tidal fresh Potomac River has resulted in the highest levels of
abundance of SAV in the river since the early 1900s. Although the exotic, H. verticillata, was the
dominant species contributing to this rapid spread, numerous other native species co-occur with this
species. Some declires in SAV were noted around Washington, DC since 1989, but these losses were
offset by the continued rapid downriver expansion of SAV below Quantico to Aquia Creek. In the
1980s, R. maritima underwent a sudden and rapid expansion in the middle mainstem Bay, as well as
in the lower Patuxent, Chester, Choptank, and Rappahannock rivers, with a subsequent decline in some
areas.
Many sections of the Bay and its tidal tributaries remain unvegetated or have very sparse SAV
populations—principally the upper western shore and Eastern Shore tributaries and where water quality
has not consistently met the SAV habitat requirements. Two major western shore tributaries—the James
and Patuxent rivers—have almost no SAV throughout their lengths. The relatively large interannual
fluci uations in SAV distribution in many areas of the Bay and its tidal tributaries support the need to
monitor SAV annually to understand the factors controlling SAV distribution and abundance.
Submerged aquatic vegetation distributional patterns in the Bay and its tidal tributaries exhibit
fairly sharp boundaries between areas with SAV and those without, indicating that relatively small
changes in water quality can lead to rapid increases or decreases in SAV populations. Ground surveys
have confirmed the presence of remnant SAV populations in small tidal creeks and tributaries (e.g.,
XII
Trends in *h: distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Executive Summary
the Patuxent River), suggesting that the presence of vegetative sources or seed banks could repopulate
riverine populations if water quality conditions improve. The recent changes in SAV populations in
the Bay suggest that most SAV populations can rebound rapidly if water quality conditions are improved
and maintained. Some areas may not become revegetated even after the return of suitable water quality
conditions, however, due to a lack of SAV propagules either within or close to these areas.
Trends in the Distribution, Abundance, and Habitat Quality of xiii
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Acknowledgments
Without the joint support of the following agencies which have supported the Chesapeake Bay
submerged aquatic vegetation aerial survey monitoring program over 15 years, the bay wide mapping
program could not have been accomplished: U.S. Environmental Protection Agency, Grant Numbers
X003465-01, -02, -03; U.S. Fish and Wildlife Service, Grant Numbers 14-16-0005-86-028, 87-9005,
90-9031, and 91-9023; Virginia Council on the Environment and Maryland Department of Natural
Resources through the Coastal Resources Management Program of the National Oceanographic and
Atmospheric Administration, Grant Numbers NA88 AA-DCZ-091,092, NA89AA-DCZ-134, NA90AA-
H-CZ796, C057-88-031, C188-90-002, C225-91-004; and a private grant from the Allied-Signal
Foundation to the College of William and Mary.
The following people or groups of people are acknowledged for their support of and/or participation
in the SAV baywide aerial survey or their assistance in preparing this report: Peter Bergstrom, U.S.
Fish and Wildlife Service, for assistance in data analysis (particularly the river flow data); numerous
Virginia Institute of Marine Science staff members, both past and present, particularly Jennifer Whiting,
Leah Nagey, Gary Anderson, Ken Moore, and Kevin Kiley, who have been involved in the digitization
of the SAV maps, data reduction or analysis, and production of the annual aerial survey reports; Adam
Frisch, Virginia Department of Environmental Quality EcoMAPS office, who provided expertise in both
the Virginia Institute of Marine Science GIS and ARC/INFO GIS programs; Jim Simons, University
of Texas, for collaborating on the baywide aerial survey from 1984 to 1986; Jennifer Gavin, Chesapeake
Research Consortium, for her review and corrections of the draft text, figures, and tables; the reviewers
of the earlier drafts of this report (Steve Bieber (Maryland Department of the Environment), Rick
Hoffman (Virginia Department of Environmental Quality), Ed Pendleton (U.S. Fish and Wildlife
Service), and Virginia Carter (U.S. Geological Survey)); the authors of the SAV Technical Synthesis
(Ken Moore, Bill Dennison, Court Stevenson, Lorie Staver, Virginia Carter, Nancy Rybicki, Ed
Hickman, Steve Bieber, and Patsy Heasly) who were instrumental in the development of the SAV habitat
requirements referred to frequently in this report; Verna Harrison, Chair of the Chesapeake Bay
Program's Living Resources Subcommittee, who ensured the continuity of the baywide aerial survey
through unwavering support; participants in the Chesapeake Bay Water Quality Monitoring Program
for ensuring the availability of the water quality data; all the various public and private groups involved
in the ground surveys that complemented the baywide aerial surveys, particularly the Citizens' SAV
Hunt and the Maryland Charter Boat Captains' survey; and the U.S. Fish and Wildlife Service and the
Chesapeake Bay Foundation for their assistance in organizing the citizens' ground surveys.
Trends in the Distribution, Abundance, and Habitat Quality of xv
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Table of Contents
EXECUTIVE SUMMARY i
ACKNOWLEDGMENTS '.'.. .....xv
TABLE OF CONTENTS xvii
CHAPTER 1: INTRODUCTION 1
CHAPTER 2: TREND ANALYSIS APPROACH 3
Chesapeake Bay SAV Species 3
Chesapeake Bay Program Segments 4
Baywide and Regional Aerial Surveys 6
SAV Ground Surveys 9
SAV Habitat Requirements 10
SAV Restoration Targets 13
Chesapeake Bay Water Quality Data 14
SAV Trend Analysis Presentation 17
CHAPTER 3: BAYWIDE SAV, HABITAT QUALITY, AND RIVER FLOW TRENDS 21
/
Baywide SAV Trends 21
Baywide Water Quality/SAV Habitat Requirement Patterns 40
Baywide Trends in SAV and River Flow 41
CHAPTER 4: REGIONAL TRENDS IN SAV DISTRIBUTION, ABUNDANCE, AND HABITAT QUALITY 45
Northern Chesapeake Bay 47
Northeast, Elk, Bohemia, and Sassafras Rivers 51
Upper Chesapeake Bay and Upper Central Chesapeake Bay 57
Bush, Gunpowder, Middle, Back, and Patapsco Rivers 62
Chester River 72
Magothy, Severn, South, Rhode, and West Rivers 75
Eastern Bay 81
Middle Central Chesapeake Bay 84
Choptank River 87
Patuxent River 92
Trends in the Distribution, Abundance, and Habitat Quality of xvii
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971-1991
-------
Nanticoke, Wicomico, Manokin, Big Annemessex, and Pocomoke Rivers 98
Tangier Sound 107
Potomac River 110
Lower Chesapeake Bay 118
Rappahannock River ....,..,.121
Western Lower Chesapeake Bay 127
Eastern Lower Chesapeake Bay 130
MobjackBay 133
York River 136
James River 142
Mouth of Chesapeake Bay , 148
REFERENCES ; , 151
APPENDIX A A-1
APPENDIX B B-1
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
APPENDIX C C-1
Table C-1. Chesapeake Bay SAV Distribution and Abundance by State in Hectares
Table C-2. Maryland SAV Distribution and Abundance in Hectares
Table C-3. Virginia. SAV Distribution and Abundance in Hectares
Table C-4. District of Columbia SAV Distribution and Abundance in Hectares
APPENDIX D D-1
Maryland Departmont of Natural Resources SAV Ground Survey Percent Stations Vegetated Data by
Chesapeake Bay Program Segment (1971 to 1990)
APPENDIX E E-1
Table E-1. Quartiles of Average Daily Susquehanna Flow per Month (1950 to 1991)
Table E-2. Quartiles of Average Daily Potomac Flow per Month (1950 to 1991)
xviii Trends in the Distribution, Abundance, and Habitat Quality of
Sibmerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971-1991
-------
chapter i introduction
"Therefore, to further our commitments made in the 1987 Chesapeake Bay
Agreement, we agree... to use the distribution and abundance of submerged
aquatic vegetation (SAV) in the Bay and its tidal tributaries, as documented
by Baywide and other aerial surveys conducted since 1970, as an initial
measure of progress in the restoration of living resources and water quality."
- From the 1992 Amendments to the Chesapeake Bay Agreement, signed by Governors Robert Patrick Casey (Pennsylvania), William
Donald Schaefer (Maryland), and Lawrence Douglas Wilder (Virginia), Mayor Sharon Pratt Kelly (District of Columbia), Senator
Bernie Fowler (Chair, Chesapeake Bay Commission), and Administrator William Reilly (U.S. Environmental Protection Agency).
Chesapeake Bay has long been renowned for _ n __,
its abundant harvestable resources. No less impor- The 1987ChesapeakeBay Agreement, signed
tant, however, is the large and diverse array of b* the §overnors of Pennsylvania, Maryland, and
non-harvestable plants and animals that contrib- Virginia, the mayor of the District of Columbia, the
utes to the complexity, balance, and beauty of this chair of the Chesapeake Bay Commission, and the
dynamic and productive estuary. administrator of theU.S. Environmental Protection
Agency, set as a major commitment the "need to
Over the last three to four decades, the decline determine the essential elements of habitat quality
of many species from overharvesting, deterioration and environmental quality necessary to support
of water quality, habitat destruction, disease, and living resources and to see that these conditions are
meteorological changes has alarmed scientists, attained and maintained" (Chesapeake Executive
managers, politicians, and the public (Horton and Council, 1987). The Submerged Aquatic Vegeta-
Eichbaum, 1991). This concern triggered scien- tion Policy for the Chesapeake Bay and Tidal
tific studies to document the magnitude and causes Tributaries (Chesapeake Executive Council, 1989)
of the declines along with basinwide agreements and the Implementation Plan for the Submerged
to protect, restore, and enhance these living re- Aquatic Vegetation Policy (Chesapeake Executive
sources. Council, 1990) were developed to guide managers
n , , . ,0 ..,. . and scientists in SAV assessment, protection, edu-
Submerged aquatic vegetation (SAV) is a ,. . ,
te.. ; , & , ,. . cation, and research.
diverse assembly of rooted macrophytes living in
the shoal areas of Chesapeake Bay—from its mouth Living resources monitoring programs are
to the headwaters of its tidal tributaries (Stevenson critical to understand fluctuations in resource abun-
and Confer, 1978; Orth et al., 1992). These plants dance. In Chesapeake Bay, baywide monitoring of
historically contributed to the high primary and SAV is necessary to assess the success of the
secondary productivity of Chesapeake Bay (Kemp restoration and protection efforts. The 1992amend-
et al., 1984). Scientists correlated the dramatic ments to the 1987 Chesapeake Bay Agreement
baywide decline of all SAV species in the late state that the distribution and abundance of SAV,
1960s and 1970s (Orth and Moore, 1983a) with documented by baywide and other aerial surveys,
increased nutrients and sediments flowing into the will be used as a measure of progress in the res-
Bay due to development of the surrounding water- toration of living resources and water quality
shed (Kemp etal., 1983). This situation galvanized (Chesapeake Executive Council, 1992). The strong
diverse groups into formulating both a policy and link between water quality and SAV distribution
an implementation plan to ensure the restoration of and abundance (Batiuk et al., 1992; Dennison et al.,
SAV in Chesapeake Bay. 1993) supports the concept that SAV is a good
Trends in the Distribution, Abundance, and Habitat Quality of ?
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chaptei 1: Introduction
barometer of Chesapeake Bay health (Orth and
Moors, 1988).
Significant progress has been made in defin-
ing habitat requirements for Chesapeake Bay's key
living resources (Chesapeake Bay Program, 1987;
Funderburk et al., 1991) with emphasis on the
Bay's SAV community iBatiuketal., l992;Dennison
et al.. 1993). Linked with these SAV habitat re-
quire-ments is a tiered set of SAV distribution
restoration goals and targets for Chesapeake Bay,
along with restoration targets for density and SAV
spechs diversity (Batiuk et al., 1992; Chesapeake
Executive Council, 1S'93; Dennison et al., 1993).
This report builds on two decades of aerial
and ground surveys of SAV distribution and abun-
dance data along with development of SAV habitat
requirements, establishment of SAV restoration
goals and targets, compilation of historical water
quality data, and implementation of a coordinated
baywide monitoring program. The objectives of
this report are to:
• describe trends in SAV distribution and
abundance in Chesapeake Bay and its tidal
tributaries from 1971 to 1991;
• relate SAV distribution over time with tiered
distribution restoration goals and targets;
• compare trends in SAV distribution and
abundance with corresponding trends in water
quality; and
• correlate SAV distribution with river flow.
Trends in (he Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
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chapter* Trend Analysis Approach
Numerous ground and aerial surveys of SAV
have been conducted in the past, particularly over
the last two decades. This chapter provides a brief
description of these surveys and their methodolo-
gies. It also includes an explanation of how SAV
distribution and abundance data were coupled with
water quality monitoring data, the SAV habitat
requirements, and the SAV restoration goals and
targets.
Chesapeake Bay SAV Species
The term "submerged aquatic vegetation,"
for the purpose of this analysis, encompasses 25
taxa from ten vascular macrophyte families and
three taxa from one freshwater macrophytic algal
family (Characeae) but excludes all other algae
(Table 1). Eleven species of SAV, exclusive of the
algae, are commonly found in Chesapeake Bay and
its tidal tributaries.
Table 1. Species of SAV Found in Chesapeake Bay and its Tidal Tributaries
Family
Species
Common Name
Characeae
Potamogetonaceae
Ruppiaceae
Zannichelliaceae
Najadaceae
Hydrocharitaceae
Pontedariaceae
Ceratophyllaceae
Trapaceae
Haloragaceae
Zosteraceae
Chara braunii Gm.
Chara zeylanica Klein ex Willd., em.
Nitella flexilis (I). Ag., em
Potamogeton perfoliatus, I. var. bupleuroides
(Femald) Farwell
Polamogeton pectinatus L
Potamogeton crispus L
Potamogeton pusillus I.
Potamogeton amplifolius
Potamogeton diversitolius
Potamogeton epihydrus
Potamogeton gramineus
Potamogeton nodosus
Ruppia maritima L
Zannichellia palustris L
Najas guadalupensis (Sprengel) Magnus
Najas gracillima (A. Braun) Magnus
Najas minor Allioni
Najas muenscheri
Najas llexilis
Vallisneria americana Michaux
Elodea canadensis (Michaux)
Egeria densa Planchon
Hydrilla verticillata (L.f.) Boyle
Heteranthera dubia (Jacquin) MacMillian
Ceratophyllum demersum L
Trapanatans L
Myriophyllum spicatum I.
Zostera marina L.
Muskgrass
Redhead grass
Sago pondweed
Curly pondweed
Slender pondweed
Widgeongrass
Homed pondweed
Southern naiad
Naiad
Wild celery
Common elodea
Waterweed
Hydrilla
Water stargrass
Coontail
Water chestnut
Eurasian water milfoil
Eelgrass
Classification and nomenclature derived from: Godfrey and Woolen, 1979 and 1981; Harvill et al., 1977 and 1981; Kartesz and Kartesz, 1980; Radford et al.,1968; Wood and Imahori, 1964 and 1965.
Sources: Brush, 1987; Brush and ,1989; Carter et al. ,1985a; Chesapeake Bay Program, unpublished data c; Davis. 1985; Hurley, 1990; Orth and Nowak, 1990; Orth et al., 1979; Paschal et al.,
1982; Rybicki et al., 1988,1987, and 1986; Stevenson and Confer, 1978; R. Younger, Personal Communication.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
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Chapter 2: Trend Analysis Approach
Zostera marina i eelgrass) is dominant in the
lower reaches of the B ay. Myriophyllum spicatum
(Eurasian watermilfo:!), Potamogeton pectinatus
(sago pondweed), Potamogeton perfoliatus (red-
head grass), Zannichellia palustris (horned
pondweed), Vallisnsria americana (wild celery),
Elodea canadensis (common elodea), Heteranthera
dubia (water stargrass.), Ceratophyllum demersum
(coontail), and Najasgtiodalupensis (southern naiad)
are kss tolerant of high salinities and are found in
the middle and upper reaches of the Bay and its tidal
tributaries (Stevenson and Confer, 1978; Orth et
al., .979; Orth and Moore, 1981, 1984). Ruppia
rnaritima (widgeongrass) tolerates a wide salinity
range and is found from the Susquehanna Flats
souti to the mouth of the Chesapeake Bay.
Approximately seventeen other species occur
only occasionally. When present, they populate
areas principally in the middle and upper reaches
of C.iesapeakeBay an din its tidal tributaries (Table
1). Hydrilla verticiliata (hydrilla), a recently in-
trodaced exotic species, dominates SAV beds in
the tidal fresh reaches of the Potomac River (Carter
and Rybicki, 1986). I: has also been reported in the
Susquehanna Flats (Orth etal., 1989, 1991, 1992),
although its growth there has not been as wide-
spread as in the Potomac River (Kollar, personal
communication).
Stevenson and Confer (1978), Carter et al.
(1983), Batiuk et al. (1992), Hurley (1992), and
Stevenson and Staver (in press) provide more detailed
descriptions of the biology and ecology of the
above species.
Chesapeake Bay
Program Segments
Chesapeake Bay Program segments are used
to present the 1971 to 1991 SAV distribution and
abundance data and the 1970 to 1991 water quality
data described here (Figure 1). In 1983, the Chesa-
peake Bay Program developed and adopted the
Chesapeake Bay segmentation scheme. It was first
published in Chesapeake Bay: Profile for Environ-
mental Change (U.S. Environmental Protection
Agency, 1983). Since then, the segmentation scheme
has been used both to design monitoring programs
and as the spatial scheme for management, analy-
sis, interpretation, and presentation of monitoring
data. The Chesapeake Bay Program (1990) has
published a complete listing of the latitude/longi-
tude coordinates for the segmentation scheme. This
scheme differs from the organizational provinces
used in the annual SAV aerial monitoring program
(see references in Table 2).
The segmentation scheme is problematic in
those segments with significant changes in SAV
distribution and abundance patterns within an in-
dividual segment (e.g., SAV is abundant in the
lower portion but absent or limited in the upper
portion of the lower York and Rappahannock riv-
ers). Although water quality in the lower portions
of these segments is apparently adequate to support
viable populations of SAV, water quality in the
upper portions is not suitable for SAV growth and
long-term survival. Median water quality condi-
tions for the delineation of habitat requirements are
derived from all monitoring stations within a seg-
ment, however, and may show that the water quality
for that segment does not meet some or all SAV
habitat requirements.
Several Chesapeake Bay Program segments
contain tidal fresh, oligohaline, and mesohaline
habitats within a single segment (principally the
Chester (ET4) and Choptank (ET5) rivers). For this
report, the more stringent set of SAV habitat re-
quirements (i.e., mesohaline requirements) was
applied to examine water quality data from 1971
to 1991. The preferred approach is to subdivide
the Chesapeake Bay Program segment by indi-
vidual salinity zones, apply the applicable SAV
habitat requirements to data collected within the
individual salinity zones, and compare these find-
ings with SAV trends for that subsection. As SAV
was absent from the tidal fresh and oligohaline
areas of these segments, however, these more detailed
analyses were not undertaken.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
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Chapter 2: Trend Analysis Approach
ET1
WT1
WT2
WT3
WT4
RET2
ET7
ET10
EE3
TFS
CBB
Figure 1. Chesapeake Bay Program segmentation scheme.
Source: Chesapeake Bay Program, 1990.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
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Chapter 2: Trend Analysis /approach
Baywide and Regional
Aerial Surveys
Submerged aqi.atic vegetation was identified
as a critical area of research, along with toxics and
nutrients, during the 1976 to 1983 research phase
of the Chesapeake Bay Program. Within the SAV
research program, three elements were funded:
assessing the baywide distribution of SAV; iden-
tifying the causes for the recent SAV decline; and
determining the role and functional value of the
SAV community (U.S. Environmental Protection
Agency, 1982).
Low-level aerial photography was used in the
firs: baywide survej in 1978 to assess the distri-
bution and abundance of SAV (Orth et al., 1979;
Anderson and Macomber, 1980). Aerial photog-
raphy acquired unde:' appropriate atmospheric and
hydrologic conditions is an effective means of
providing a synoptic: picture of SAV distribution
(Orth and Moore, 1983b).
Regional SAV aerial surveys were conducted
in 1980 and 1981 (Virginia only) (Chesapeake Bay
Program, unpublished data b). Orth et al. (1985)
con ducted the next bay wide survey in 1984. Using
similar methodologies, subsequent baywide sur-
veys were conducted from 1985 to 1987 and from
1989 to 1991 (Orthetal., 1986,1987,1989,1991,
and 1992; Orth and Nowak, 1990). Sections of the
lower Chesapeake Bay were photographed for SAV
in 1974 and were compared with 1971 photographs
taken for purposes other than mapping SAV! Both
sets of photographs clearly delineated SAV beds
(Orth and Gordon, 1975). Although aerial photo-
graphs were taken of sections of the Bay in Maryland
and Virginia in 1979, and baywide in 1988, SAV
beds were not mapped from this photography due
to the late date of photoacquisition and the poor
quality of the photographs. Table 2 summarizes
SAV data available from the aerial surveys con-
ducted between 1971 and 1991.
Vertical aerial photography (1:24,000), black
and white or color, was the principal source of
information used to assess the distribution and
abundance of SAV. Photographs taken under optimal
atmospheric, water, and biological conditions (i.e.,
low sun angle, little or no wind, minimal cloud or
haze cover, low tide, and maximum standing bio-
mass of SAV) insured optimal contrast in the imagery
for SAV photointerpretation. Submerged aquatic
vegetation beds were mapped directly onto USGS
7.5-minute quadrangles of transparent mylar and
digitized into a geographic information system.
Table 2. Baywide and Regional SAV Aerial Surveys
Yoar
Areas Surveyed
Reference
1£71 Lower Western Shore
1 £74 Lower Western Shore
1£78 Chesapeake Bay
1S79 Upper Western Shore-Maryland
1£'80 Virginia
1S81 Virginia
1£84 Baywiae
1£85 Baywide
1S86 Baywide
1£87 Baywide
1£89 Baywide
1990 Baywide
1S91 Baywide
Orth and Gordon, 1975
Orth and Gordon, 1975
Anderson and Macomber, 1980; Orth et al., 1979
Chesapeake Bay Program, unpublished data (a)
Chesapeake Bay Program, unpublished data (b)
Chesapeake Bay Program, unpublished data (b)
Orth et al., 1985
Orth et al., 1986
Orth et al., 1987
Orthetal., 1989
Orth and Nowak, 1990
Orth et al., 1991
Orth et al., 1992
Trends in the Distribution, Abundance, and Habitat Quality of
Sut merged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
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Chapter 2: Trend Analysis Approach
The scale of the photography and that of the 7.5-
minute quadrangles were similar, allowing the
photointerpreter to overlay the transparent map
onto the photograph for S AV bed delineation. Minor
differences in scales were adjusted for by shifting
the map to assure an adequate number of ground
control points and by outlining the SAV over small
sections of the photograph at any given point. The
reports cited in Table 2 give detailed descriptions
of the methodologies for photography (e.g., cam-
eras, film types, and guidelines for the acquisition
of photographs), mapping and reporting proce-
dures, and quality control and quality assurance
procedures (Orth and Moore, 1983b; Orth et al.,
1988).
The aerial survey and mapping program ini-
tiated in 1978 provides a bay wide perspective of
SAV distribution. This program is the foundation
for tidal tributary and mainstem Bay segment-
specific comparisons of SAV distribution and
abundance with water quality data collected through
the Chesapeake Bay Water Quality Monitoring
Program.
The figures displaying annual SAV distribu-
tion and abundance data include all years for which
baywide or regional aerial survey data were avail-
able for shoreline and shallow water habitats within
Chesapeake Bay Program segments, with two
exceptions. Data from the 1979 regional aerial
survey of Maryland were not included in the analy-
sis of distribution and abundance trends because
the mapped portion of the upper Bay was photo-
graphed very late in the SAV growing season. Data
from the 1980 and 1981 regional (Virginia Bay
only) aerial surveys were not included in the analy-
sis of trends for Tangier Sound (EE3) and Lower
Chesapeake Bay (CBS) segments because corre-
sponding data for Maryland portions of these segments
were not available. Data from these regional sur-
veys were used, however, in the development of the
Tier I SAV distribution restoration goal.
To compare the SAV distribution and abun-
dance figures between segments and simultaneously
I To convert to acres, multiply hectares by 2.47.
reflect the vast differences in distribution, only four
y-axis scales were used: 0-100,0-250,0-2000, and
0-5000 hectares. Each figure caption states the Tier
I SAV distribution restoration goal for that segment
(see the section below on restoration goals and
targets). All SAV distribution data, restoration goals,
and restoration targets are presented in hectares1.
Estimates of SAV bed densities (collectively
referred to as abundance) are presented within each
SAV distribution trend figure. During the SAV bed
delineation process, a visual estimate of the percent
cover within each bed was made and compared to
an enlarged crown density scale (similar to those
used for estimating forest tree crown cover from
aerial photography) (Orth et al., 1991). The bed
density was classified into one of four categories
based on a subjective visual comparison with the
density scale. These categories were: 1 = very
sparse (<10 percent coverage); 2 = sparse (10-40
percent); 3 = moderate (40-70 percent); or 4 = dense
(70-100 percent). The number of hectares in each
density category for all SAV beds within a segment
is illustrated in each SAV distribution trend figure.
No density information was reported for the Vir-
ginia 1971 and 1974 aerial surveys or the Maryland
1978 SAV aerial survey.
The percent cover value presents a direct vi-
sual comparison of the photographic image and the
crown density scale. It does not represent a mea-
surement of biomass or standing crop of the SAV
community. This crown density scale index is
affected by photographic quality. Analysis of change
in the percent cover over time in this index requires
both consistent conditions and photography from
year to year. Differences in the scale of photogra-
phy or changes in water quality, for example, will
yield an inconsistent index. The degree of contrast
in the photographs will affect the resolution of
features within SAV habitats, altering visual esti-
mates of heterogeneity. Overestimation of percent
cover may result if adjacent patches of plants appear
to blend into one another. Underestimation of per-
cent cover may result if small plants, spaced between
dense patches of larger plants, cannot be distin-
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
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Chapter 2: Trend Analysis Apsroach
guished and are interpreted as background sedi-
ment . Classification eitors will be greatest when the
SAV percent cover is close to either the upper or
lower limit of another density category. Consistent
repo:ting of this inde >c requires that photographic
missions and subseque nt products be carefully scru-
tinized immediately gfter acquisition to allow for
another overflight of those areas not meeting the
predjscribed conditions.
All data presented in each SAV distribution
trend figure are also presented in tabular format for
each Chesapeake Bay Program segment. Hectares
have been rounded to the nearest whole number.
Whe n less than one hectare was reported, the num-
ber was treated as a one both in calculating the
segment total and in determining the percent achieve-
ment of the Tier IS AV distribution restoration goal
and the Tier III SAV distribution restoration target.
Yearly SAV distribution data are also presented as
percentages of these goals and targets for each
Chesapeake Bay Program segment. Each table
caption provides the segment-specific numerical
Tier I distribution restoration goals and Tier III
distribution restoration targets.
Submerged aquatic vegetation distribution data
are ilso provided in tables summarizing coverages
for the entire Bay, the upper, middle, and lower
regions of the Bay, and the states of Maryland,
Virginia, and Delaware, and the District of Colum-
bia (Appendix C).
Delineation of SAV beds from aerial photog-
raphy usually results in an underestimation of the
bed area. Only SAV represented by an identifiable
and verified habitat signature in the photographs is
delineated. The degree of underestimation of the
bed area depends upon atmospheric andhydrologic
conditions at the time of photoacquisition as well as
the nature of the subject area. Guidelines estab-
lished for the bay wide SAV aerial survey minimize
these errors (Orth and Moore, 1983b; Orth et al.,
19£8; Dobson, et al., in press). Edges of SAV beds,
particularly those along the outer deeper portions of
the beds, are often most difficult to delineate. The
plants along these outer edges tend to be patchy and
may be obscured by turbid water. Areas with SAV
under a minimum detection limit (usually patches
of one square meter or less (Dobson et al., in press))
are generally not mapped because they are too small
to be detected at the altitude of the aerial overflights.
Generally, SAV beds that are considered very sparse
in the baywide aerial surveys have many small
patches that are at or just above the minimum
detection limit. These areas are easily overlooked
because they are not clearly visible on photographs
taken under sub-optimal conditions. Such areas
may be mapped in subsequent years if patches have
grown or coalesced to a size greater than the mini-
mum detection unit. In addition, small patches of
SAV in some tidal creeks are impossible to map and
digitize. These creeks are usually represented by a
single line on the 7.5-minute USGS quadrangles;
the SAV beds are smaller than the creek itself.
Errors may be introduced throughout the pro-
cess of photoacquisition, photointerpretation, and
digitization. Errors from the photoacquisition and
photointerpretation phases have not been fully quan-
tified in either the baywide SAV aerial survey or in
other aerial surveys (Dobson et al., in press), result-
ing in an incomplete statistical understanding of
these types of data. Error analysis might require
replicate flights to produce multiple images of the
same SAV bed and photointerpretation of each set
of photographs. Such an analysis would also neces-
sitate an intensive ground survey to delineate the
boundaries of the bed in situ.
Digitization errors are easier to quantify. The
quality assurance/quality control guidelines estab-
lished for the baywide aerial survey state that data
are unacceptable if the digitizing error rate exceeds
5 percent of the mean of the iterations (Orth et al.,
1988). The digitizing error rate of the baywide aerial
survey for most SAV polygons is 1 percent or less,
but is somewhat higher for very small beds (gener-
ally those less than one hectare). The width of a one
millimeter line on a 1:24,000 scale, 7.5-minute
quadrangle equals 24 meters on the ground. The
pencil line defining the SAV polygon can vary from
approximately 0.2 to 0.5 millimeters in width, equiva-
lent to a distance of 4.8 to 12.0 meters on the map.
Even a slight repositioning of the line from the true
Trends in the Distribution, Abundance, and Habitat Quality of
Suomerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 2: Trend Analysis Approach
edge of a SAV bed, coupled with digitizer error,
could yield either a cumulative error if the two are
additive or a zero error if they cancel each other.
Similar problems have occurred in delineating
historical shoreline changes. Crowell et al. (1991)
presented several worst case scenarios in estimating
the location of the high water mark. Estimates
ranged from 6.1 to 8.9 meters, although the authors
state that the magnitude of error is usually much less
using post-compilation accuracy assessments.
Despite the potential errors described above,
the SAV distribution and abundance data generated
through the baywide SAV aerial survey have been
gathered using a consistent approach and interpre-
tation for the past two decades. In addition, the
questions being addressed through the baywide aerial
survey program do not require monitoring of every
square meter of SAV in Chesapeake Bay. Many
standard statistical tests can not be used on the
distribution and abundance data because spatial and
temporal statistical comparisons of bed polygons
are difficult.
SAV Ground Surveys
Numerous quantitative and qualitative SAV
ground surveys have been conducted throughout
Chesapeake Bay over the last several decades, sev-
eral of which have supported the baywide SAV
aerial survey program. The latter include surveys
by: the Citizens' SAV Hunt Program (baywide:
1985 to 1991); Maryland's Charterboat Captains'
Survey (Maryland: 1985 to 1990); U.S. Fish and
Wildlife Service (Maryland and Potomac River:
1990 to 1991); Stan Kollar of Harford Community
College (upper Chesapeake Bay: 1984 to 1991);
Northern Virginia Community College (Potomac
River: 1984); U.S. Geological Survey (Potomac
River: 1984 to 1989); Essex Community College
(Maryland: 1990 to 1991); Metropolitan Washing-
ton Council of Governments (Potomac River: 1990
to 1991); Maryland National Capital Planning and
Parks Commission (Patuxent River: 1990 to 1991);
University of Maryland Horn Point Environmental
Laboratory (Maryland: 1984 to 1991); and the Vir-
ginia Institute of Marine Science (Virginia: 1984 to
1991). Methodologies for each of these ground
surveys can be found in the appropriate SAV dis-
tribution and abundance reports for the year of the
particular baywide aerial survey (Table 2).
Several SAV ground surveys, independent of
the baywide SAV aerial survey, have been con-
ducted over the last two decades. Most notable were
surveys conducted by the U.S. Fish and Wildlife
Service Migratory Bird and Habitat Research Labo-
ratory/Maryland Department of Natural Resources
SAV ground survey which recorded the presence,
absence, and species diversity of SAV at over 600
stations annually in the Maryland portion of Chesa-
peake Bay from 1971 to 1991 (Chesapeake Bay
Program, unpublished data c) and the U.S. Geologi-
cal Survey intensive SAV survey in the Potomac
River from 1978 to 1981 (Haramis and Carter,
1983) and subsequent surveys documenting SAV
recovery in the Potomac River (Carter et al., 1985b;
Carter and Rybicki, 1986; Rybicki and Schening,
1990; Rybicki et al., 1985, 1986, 1987, and 1988).
Other surveys between 1971 and 1991 included: the
Rhode River from 1966 to 1973 (Southwick and
Pine, 1975); Eastern Bay (Stevenson and Confer,
1978); the Milfoil Survey from 1957 to 1977 (Bayley
et al., 1978); and a 1990 U.S. Fish and Wildlife
Service survey of clams in upper and middle Chesa-
peake Bay (Jorde et al., 1991).
The Maryland Department of Natural Re-
sources SAV ground survey data (1971 to 1991)
are presented by Chesapeake Bay Program seg-
ment as the percentage of the total number of
stations visited at which rooted SAV was observed.
Each figure caption lists the individual years for
which data were not available. Appendix D pro-
vides a complete listing of Maryland Department
of Natural Resources ground survey data. Because
of methodological differences, the baywide aerial
survey reported SAV in many locations where the
Maryland Department of Natural Resources ground
survey reported no SAV. This discrepancy has
caused problems in areas where vegetation is sparse.
In these areas, the baywide aerial survey may report
a bed in density class 1 (<10 percent coverage) or
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chaptsr 2: Trend Analysis Af proach
2 (10-40 percent coverage), while the Maryland
Department of Natural Resources ground survey
may not even sample the vegetation if the sampling
stati 3n is in the unvegetated portion of the bed and
would report no SAV present. The other major
methodological difference between these two sur-
veys is that many of Maryland Department of
Natural Resources ground survey sampling sta-
tions are in water depths of more than one meter
below mean low water. The baywide aerial survey
has shown that most .'SAV beds are in water depths
less than one meter. The 1985 and 1986 SAV
distribution reports positioned Maryland Depart-
ment of Natural Resources ground survey sampling
stations on the same naps with the SAV polygons
mapped from the bay wide aerial survey. The
Maryland Department of Natural Resources ground
sun ey stations were located in deeper waters than
the SAV beds that were photographed and mapped
in those years (Orth et al., 1986 and 1987).
Submerged aquatic vegetation ground sur-
veys prior to 1971 iinclude a 1,000-transect survey
of the upper Chesapeake Bay between 1967 and
1969 (Stotts, 1970) and a benthic survey of the
upper Chesapeake B ay from 1959 to 1960 (Stotts,
1960).
Stevenson and Confer (1978) and Stevenson
and Staver (in press) describe the methodologies
and results for the SAV ground surveys listed
above. More detailed information can be obtained
from the cited repons and papers. All the above
described ground surveys, when coupled with the
baywide aerial surveys, are extremely important in
describing and understanding SAV distribution
patterns on a local or regional scale.
SAV Habitat Requirements
For SAV to grow and survive in any area,
wa:er quality must be within the environmental
tolerances of those species. Each species can live
within an envelope of water quality conditions that
define its survival and growth requirements. Chroni-
cally exceeding the value for one critical parameter
can potentially lead to the loss of SAV in an area.
The Chesapeake Bay Submerged Aquatic Vegeta-
tion Habitat Requirements and Restoration Targets:
A Technical Synthesis identified the minimum habitat
requirements for SAV in different regions of the
Chesapeake Bay (Batiuk et al., 1992).
Submerged aquatic vegetation habitat require-
ments have been defined as the minimal water
quality levels necessary for the plants' survival.
The water quality parameters used in the delinea-
tion of these SAV habitat requirements were chosen
because of their relevance to the survival of the
vegetation (Figure 2). The principal environmental
water quality parameters for submerged aquatic
plants are: light attenuation coefficient, total sus-
pended solids, chlorophyll a, dissolved inorganic
phosphorus, and dissolved inorganic nitrogen.
Submerged aquatic vegetation habitat require-
ments were formulated by: determining SAV
distributions by transplant survival and baywide
distributional surveys; measuring water quality char-
acteristics along large-scale transects that spanned
vegetated and non-vegetated regions; and combin-
ing distribution data and water quality levels to
establish the minimum water quality conditions
that allow SAV survival. This type of analysis
(referred to as correspondence analysis) was strength-
ened by factors common to each of the case studies.
Field data were collected over several years (almost
a decade in the Potomac River) under varying
meteorologic and hydrologic conditions by differ-
ent investigators. Distributions of SAV in four case
studies (Susquehanna Flats, upper Potomac River,
Choptank River, and York River), across all salin-
ity regimes, were responsive to the five water
quality parameters used to develop the SAV habitat
requirements. In addition, as the water quality changed
from year to year, its improvement or degradation
was reflected by the resultant spread or decline of
the regional SAV populations.
Habitat requirements for SAV survival and
growth were developed based on the analysis and
interpretation of seasonal medians of water quality
data. Median values were used to characterize the
water quality conditions to which SAV was ex-
posed over an annual growing season (April to
10 Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 2: Trend Analysis Approach
Conceptual Model of SAV/Habitat Interactions
Light
Water
Chlorophyll a
Total
Suspended
Solids
Particles
Water Column
Light
Attenuation
(Kd)
Epiphytes
Leaf Surface
Light
Attenuation
Figure 2. The availability of light for SAV is determinedby light attenuation processes. Watercolumn attenuation, measured
as light attenuation coefficient {Kd), results from absorption and scatter of light by particles in the water (phytoplankton
measured as chlorophyll a; total organic and inorganic particles measured as total suspended solids) and by absorption
of light by water itself. Algal epiphytes growing on SAV leaf surfaces also contribute to light attenuation. Dissolved inorganic
nutrients (DIN = dissolved inorganic nitrogen; DIP = dissolved inorganic phosphorus) contribute to the phytoplankton and
epiphyte components of overal! light attenuation. Epiphyte grazers control the accumulation of epiphytes.
Source: BatiuketaL, 1992.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
11
-------
Chapter 2: Trend Analysis Approach
Ocl ober for mesohali ne, oligohaline, and tidal fresh
areas; March to November for polyhaline regions).
Median values were chosen because they are more
ace urate estimators o f "average" or "typical" values
tha:i mean values when data have a skewed and/
or c ensored distribution (refer to page 15 in Batiuk
et al. (1992) for additional information on these
determinations).
The diversity cf SAV communities through-
out Chesapeake Bay, along with the Bay's wide
salinity range, demanded that separate habitat re-
quirements be used for different regions based on
salinity. The minimum water quality conditions
required to support the survival, growth, and repro-
duc tion of SAV to \\ ater depths of one meter were
used as the set of SAV habitat requirements ref-
ere need in this repori (Table 3). For SAV to survive
to one meter, light attenuation coefficients <2 nr
1 for tidal fresh and oligohaline regions and <1.5
m"1 for mesohaline and polyhaline regions are nec-
essary. Total suspended solids concentrations of
mg/L and chlorophyll a concentrations of <15
ug/L are consistent requirements for all regions.
Thi; habitat requirements for dissolved inorganic
nitrogen and dissol ved inorganic phosphorus, how-
ever, varied substantially among the salinity regimes.
In tidal fresh and cligohaline regions, SAV can
survive episodic and chronic high dissolved inor-
gar.ic nitrogen. Consequently, habitat requirements
for dissolved inorganic nitrogen were not deter-
mined for these regions. In contrast, maximum
dis >olved inorganic nitrogen concentrations of <0.15
mg/L were established for mesohaline and polyhaline
regions. The SAV habitat requirement for dis-
solved inorganic phosphorus was concentrations
<0 02 mg/L for all regions except in mesohaline
areas where it was <0.01 mg/L. Differences in the
nutrient habitat requirements in different regions
of :he Chesapeake Bay are consistent with obser-
vations from a variety of estuaries where shifts
occur in the relative importance of phosphorus
versus nitrogen as the; limiting nutrient (e.g., Valiela,
19H4).
The SAV habitat requirement for two-meter
restoration for light attenuation was derived using
an exponential light attenuation equation which
quantitatively defines the interrelationships among
light attenuation, minimum light requirements, and
depth penetration (Batiuk et al., 1992). The result-
ant habitat requirement was a light attenuation
coefficient <0.8 m'1, based on 20 percent surface
irradiance as the minimum light requirement. Habitat
requirements for two-meter restoration could not
be determined for the four other water quality
parameters.
The SAV habitat requirements represent the
absolute minimum level of water quality necessary
to sustain plants in shallow water. As such, exceed-
ing any of the five characteristics will seriously
compromise the chance of SAV survival. Improve-
ments in water clarity to promote greater depth
penetration of SAV would also increase SAV density
and biomass. In addition, improving water quality
beyond the habitat requirements could lead to the
maintenance or re-establishment of a diverse popu-
lation of native SAV species. Submerged aquatic
vegetation habitat requirements also provide a
guideline for mitigation efforts using transplants.
If SAV habitat requirements are not met, re-estab-
lishment of SAV communities via transplants would
be futile.
Water quality data that meet the particular
SAV habitat requirements for those years that data
were available are presented for each segment.
Years for which there were no data available to
calculate growing season medians are indicated
with "ND." Those years in which data were
available to calculate a growing season median for
at least one SAV habitat requirement (but the
applicable SAV habitat requirements were not met)
are indicated with a "0." Each figure caption lists
the individual years, by SAV habitat requirement
parameter, for which data were not available to
calculate growing season medians. The numbers of
SAV habitat requirements for which growing sea-
son medians could be calculated are labeled above
the histogram bars when data were not available for
all applicable habitat requirements.
12 Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake.Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 2: Trend Analysis Approach
Table 3. Chesapeake Bay SAV Habitat Requirements
SAV Habitat Requirements For One-Meter Restoration1
Habitat Requirements Which Affect
Water Column/Leaf Surface Light Attenuation
Light Total Dissolved Dissolved
Attenuation Suspended Chlorophyll Inorganic Inorganic Critical
Salinity Coefficient Solids a Nitrogen Phosphorus Life
Regime2 (nr1y (mg/L) (ug/L) (mg/L) (mg/L) Period
Tidal Fresh <2 <15 <15 - <0.02 April-
October
Oligohaline <2 <15 <15 — <0.02 April-
October
Mesohaline <1.5 <15 <15 <0.15 <0.01 April-
October
Pdyhaline <1.5 <15 <15 <0.15 <0.02 March-
November
1 . The SAV habitat requirements are applied as median values over the April to C
for tidal fresh, oligohaline, and mesohaline salinity regimes. For polyhaline salinity
requirements are applied as median values from combined March to May and
data. Light attenuation coefficient should be applied as the primary habitat rec
habitat requirements should be applied to help explain regional or site-specific
and leaf surface light attenuation which can be directly managed.
2. Tidal fresh = <0.5 ppt; oligohaline = 0.5-5 ppt; mesohaline = >5-18 ppt; and |
3. For determination of Secchi depth habitat requirements, apply the conversion
Secchi depth = 1.45/light attenuation coefficient.
Source: Batiuk et al., 1992.
SAV Habitat Requirements
For Two-Meter Restoration1
Light
Attenuation Critical
Coefficient Life
(mr1)3 Period
<0.8 April-
October
<0.8 April-
October
<0.8 April-
October
<0.8 March-
November
>ctober critical life period
regimes, the SAV habitat
September to November
juirement; the remaining
causes of water column
jolyhaline = >18 ppt.
factor:
SAV Restoration Targets
To evaluate the success of Chesapeake Bay
restoration and protection strategies, SAV distribu-
tion will continue to be used as a measure of the
effectiveness of the different water quality and
resource management strategies (Chesapeake Ex-
ecutive Council, 1992). To provide management
agencies with a stepwise measure of progress, a
tiered set of three SAV distribution restoration
targets has been established (Batiuk et al., 1992)
(Tables 4 and 5).
Each SAV distribution restoration goal (Tier
I) and target (Tiers n and III) represents the in-
crease in SAV acreage expected over time in response
to achievement of the habitat requirements for one
and two-meter restoration. Distribution restoration
targets were developed by mapping potential SAV
habitat on U.S. Geological Survey quadrangles and
comparing these areas with the historical survey
data and more recent distribution data (Batiuk et
al., 1992) (Figure 3). For the Tier III SAV resto-
ration target, potential habitat was defined as all
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
13
-------
Chaf ler 2: Trend Analysis Approach
shoil areas of the Bay under two meters. Histori-
cally, SAV in Chesapeake Bay may have grown in
areas with depths to three meters. The two-meter
depth contour was :hosen, however, because it
represented a reasonable estimate considering the
anticipated maximum depth penetration of most
SAY species given suitable water quality (Table 3).
Certain areas were excluded since they were un-
likely to support SAV (even with significantly
improved water quality) based on long-term his-
torical observation and recent survey information.
The Chesapeake Exec utive Council has since adopted
the Tier I SAV restoration target as a living re-
source restoration goal for the Chesapeake Bay
Program (Chesapeake Executive Council, 1993).
Chesapeake Bay
Water Quality Data
The water quality data used to determine
whuther SAV habitat requirements were met from
1970 to 1991 were acquired from two sources: the
ChesapeakeBay Program's historical water quality
data base and the bay wide water quality monitoring
program data base (Chesapeake Bay Program, 1993a,
1993b).
The 1970 to 1983 water quality data were
extracted from 16 data sets stored within the Chesa-
peake Bay Program's historical water quality data
base. Appendix A provides narrative summaries of
each of these data sets. In sharp contrast to more
recent data (1984 to 1991), the temporal and spatial
coverage of the 1970 to 1983 data are highly vari-
able both within and between years. Samples collected
prior to 1984 were chemically analyzed using a
variety of methods which resulted in widely rang-
ing detection limits. No reasonable way of accounting
for these imbalances was found or attempted in the
trend analysis. Within a Chesapeake Bay Program
segment, when only one water column surface data
point was collected within the defined critical life
period, the single observation was used in place of
Table 4. Chesapeake Bay
RESTORATION
TARGET
Tier 1 - Composite b;ds
T er II - One-meter
Ter III - Two-meter
Source: Batiuketal., 1991!.
SAV Distribution Restoration Targets
DESCRIPTION
Restoration of SAV to areas currently or previously inhabited
by SAV as mapped through regional and baywide aerial
surveys from 1971 to 1990.
Restoration of SAV to all shallow water areas defined as
existing or potential SAV habitat down to a depth of one meter,
excluding areas identified as unlikely to support SAV based on
historical observations, recent survey information, and exposure.
Restoration of SAV to all shallow water areas defined as existing
or potential SAV habitat down to the two-meter contour, excluding
areas identified under the Tier II target as unlikely to support SAV
as well as several other areas between one and two meters.
AREA
(hectares)
46,025
In progress
247,658
14
Trends in the Distribution, Abundance, and Habitat Quality of
Suamerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 2: Trend Analysis Approach
Table 5. Chesapeake Bay SAV Distribution Restoration Tier 1 Goal and Tier III Target by Chesapeake Bay Program Segment
CBP
Segment
CB1
CB2
CB3
CB4
CBS
CB6
CB7
CBS
WT1
WT2
WT3
WT4
WT5
WT6
WT7
WT8
TF1
RET1
LE1
TF2
RET2
LE2
TF3
RET3
LE3
TF4
RET4
LE4
WE4
TF5
RETS
LE5
ET1
ET2
ET3
ET4
ET5
ET6
ET7
. ET8
ET9
ET10
EE1
EE2
EE3
TOTALS
Sources: Batiuk et
Northern Chesapeake Bay
Upper Chesapeake Bay
Upper Central Chesapeake Bay
Middle Central Chesapeake Bay
Lower Chesapeake Bay
Western Lower Chesapeake Bay
Eastern Lower Chesapeake Bay
Mouth of Chesapeake Bay
Bush River
Gunpowder River
Middle River
Back River
Patapsco River
Magothy River
Severn River
South/Rhode/West Rivers
Upper Patuxent River
Middle Patuxent River
Lower Patuxent River
Upper Potomac River
Middle Potomac River
Lower Potomac River
Upper Rappahannock River
Middle Rapahannock River
Lower Rappahannock River
Upper York River
Middle York River
Lower York River
Mobjack Bay
Upper James River
Middle James River
Lower James River
Northeast River
Elk/Bohemia Rivers
Sassafras River
Chester River
Choptank River
Nanticoke River
Wicomico River
Manokin River
Big Annemessex River
Pocomoke River
Eastern Bay
Lower Choptank River
Tangier Sound
al., 1992; Chesapeake Bay Program, 1990.
Tier I
SAV Restoration
Goal
(Hectares)
3,101
139
817
103
6,309
783
4,624
86
24
353
349
0
53
240
189
78
6
16
132
3,098
1,847
282
0
0
1,714
0
0
309
5,902
0
13
16
7
467
167
1,506
191
0
0
271
363
0
2,474
3,646
6,340
46,025
Tier III
SAV Restoration
Target
(Hectares)
6,975
3,086
3,426
3,496
15,083
2,923
11,803
1,928
1,836
3,056
839
1,061
1,452
838
883
1,970
890
959
2,653
8,304
7,443
18,012
3,293
5,928
9,342
1,614
2,915
4,822
12,529
5,780
4,987
13,841
1,207
2,967
1,515
5,812
3,009
4,082
2,648
3,763
2,044
495
8,815
11,648
35,686
247,658
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
15
-------
Chapter 2: Trend Analysis Approach
SAV beds
Adjacent land-
Z
3. SAV composite map and the one and
two meter depth contours overlaid.
Areas delineated as
unlikely to suppor: SAV
deleted from the map.
1. Data from the 1971,1974, 1978,
1979, 1980, 1981, 1984-1987,
1989, and 1990 regional and
baywide SAV aerial surveys
overlaid to develop composite
maps of SAV distribution plotted
by USGS quadrangle.
2. The one and two-meter depth
contours digitized from NOAA
bathymetry maps and plotted by
USGS quadrangle.
4. Composite map reviewed by
SAV principal investigators;
areas unlikely to support SAV
delineated and annotated.
Area unlikely to
support SAV
Chesapeake Bay SAV Distribution
Restoration Targets
Three-tiered SAV distribution
restoration targets delineated
and maps of SAV distribution
restoration targets by USGS
quadrangle produced along with
tables of acreages by USGS
quadrangle, Chesapeake Bay
SAV Aerial Survey segment,
and Chesapeake Bay Program
segment.
Figure 3. Process fcr setting Chesapeake Bay SAV distribution restoration targets.
Source: Batiuket al. 1992.
16 Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 2: Trend Analysis Approach
a calculated median value. Appendix B lists the ments and growing season were defined (Table 6).
number of data points used to calculate the growing The median value within a growing season was
season median. determined for each parameter for each year for
. each segment using the SAS procedure PROC
Recognition of the limited temporal and spa- UNIVARIATE (SAS Institute, 1990).
tial data coverage within individual segments should
guide the interpretation of historical water quality These median values were then compared
data (pre-1984 or pre-1986 in some tidal tributar- directly with the applicable SAV habitat require-
ies) based on achievement of the SAV habitat ment (Table 6). Appendix B provides both a complete
requirements. The historical data are useful in listing of median water quality data and compari-
assessing overall patterns in meeting the minimum sons with applicable SAV habitat requirements.
SAV habitat conditions, but do not provide docu- _, . . , ,,rt/v,. ,, , , .. ,
t . t, t ... * •* ui r Batiuketal. (1992) addressed the usefulness
mentation that past conditions were suitable for . .. , . . . , , ,
„... -,. . of mid-channel monitoring data for describing en-
SAV survival and growth. . , ... °. , „.,,
vironmental conditions on shoals where SAV occurs.
The 1984 to 1991 water quality data were Results from a comparison of mid-channel and
extracted from the Chesapeake Bay Water Quality nearshore data from the York, Choptank, and upper
Monitoring Program data base. These bay wide data Potomac rivers and the upper Chesapeake Bay
were taken at over 160 stations through the coop- indicated that mid-channel data may be success-
erative efforts of Maryland, Virginia, the District fully used to characterize seasonal levels of water
of Columbia, and the U.S. Environmental Protec- quality in adjacent nearshore areas. Individual mid-
tion Agency. The Chesapeake Bay Basin Monitoring channel data points do not necessarily have a
Program Atlas (Chesapeake Bay Program, 1989) predictive relationship with nearshore observations,
summarizes the station locations, sample collec- but seasonal aggregations of mid-channel water
tion, and analysis methods. quality can provide reliable estimates of nearshore
water quality conditions for all five SAV habitat
From both the historical and baywide moni- requirement parameters. Follow-up comparisons
toring program data sets, surface (defined as zero of mid-channel and nearshore water quality data by
to three meters) water quality data were extracted the Chesapeake Bay Program (1992) yielded simi-
for the following parameters: Secchi depth, total lar findings and conclusions.
suspended solids, chlorophyll a, dissolved inor-
ganic nitrogen (nitrite/nitrate + ammonia), and CAW Ttvanrf Analv
-------
Chapte' 2: Trend Analysis Approach
Table 6. Applicable SAV Habitat Requirements
Segment
CBP SEG SALINITY REGIME Kd
CB1 Tidal Fresh
CB2 Oligohaline
063 Mesohaline
C64 Mesohaline
CBS Mesohaline
CB6 Polyhaline
CB7 Polyhaline
CBS Polyhaline
WT1 Oligohaline
WT2 Oligohaline
WT3 Oligohaline
WT4 Oligohaline
WTE Mesohaline
WT6 Mesohaline
WT7 . Mesohaline
WTC Mesohaline
TF1 Oligohaline
RET1 Mesohaline
LE1 Mesohaline
TF2 Tidal Fresh
RET2 Oligohaline
LE2 Mesohaline
TF3 Oligohaline
RET 3 Mesohaline
LE3 Mesohaline
TF4 Oligohaline
RET 4 Mesohaline
LE4 Polyhaline
WE4 Polyhaline
TF5 Tidal Fresh
RETS Oligohaline
LE5 Mesohaline
ET1 Oligohaline
ET2 Oligohaline
ET3 Oligohaline
ET4 Mesohaline
ET5 Mesohaline
ET6 Mesohaline
ET7 Mesohaline
ET8 Mesohaline
ET9 Mesohaline
ET10 Mesohaline
EE1 Mesohaline
EE2 Mesohaline
EEc Mesohaline
Kd - Light attenuation coefficient (rrv1)
TSS = Total suspended solids (mg/L)
CHL a = Chlorophyll a (ng/L)
DIN = Dissolved inorganic n trogen (mg/L)
2.0
2.0
1.5
1.5
1.5
1.5
1.5
1.5
. 2.0
2.0
2.0
2.0
1.5
1.5
1.5
1.5
2.0
1.5
1.5
2.0
2.0
1.5
2.0
1.5
1.5
2.0
1.5
1.5
1.5
2.0
2.0
1.5
2.0
2.0
2.0
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
, Salinity Regime, and Growing Season by Chesapeake Bay Program
TSS CHL a DIN DIP SAV GROWING SEASON
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
•
•
0.15
0.15
0.15
0.15
0.15
0.15
•
•
*
*
0.15
0.15
0.15
0.15
•
0.15
0.15
•
t
0.15
t
0.15
0.15
•
0.15
0.15
0.15
•
•
0.15
•
•
•
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.02
0.02
0.01
0.01
0.01
0.02
0.02
0.02
0.02
0.02
0.02
0.02
0.01
0.01
0.01
0.01
0.02
0.01
0.01
0.02
0.02
0.01
0.02
0.01
0.01
0.02
0.01
0.02
0.02
0.02
0.02
0.01
0.02
0.02
0.02
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
March-May, Sept-Nov
March-May, Sept-Nov
March-May, Sept-Nov
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
March-May, Sept-Nov
March-May, Sept-Nov
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
Apr-Oct
DIP = Dissolved inorganic phosphorus (mg/L)
• = No DIN habitat requiremant defined for the tidal fresh or Oligohaline
Soirees: Batiuk et al., 1992: Chesapeake
Bay Program,
1993b.
salinity
regime
18
Trends in the Distribution, Abundance, and Habitat Quality of
Subnerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 2: Trend Analysis Approach
ments for the following regions of the mainstem
Bay and tidal tributaries:
Northern Chesapeake Bay (CB1)
Northeast, Elk, Bohemia, and Sassafras rivers
(ET1, ET2, ET3)
Upper Chesapeake Bay and Upper Central
Chesapeake Bay (CB2, CBS)
Bush, Gunpowder, Middle, Back, andPatapsco
rivers (WT1,WT2, WT3, WT4, WT5)
Chester River (ET4)
Magothy, Severn, South, Rhode, and West
rivers (WT6, WT7, WT8)
Eastern Bay (EE1)
Middle Central Chesapeake Bay (CB4)
Choptank River (EE2, ET5)
Patuxent River (LEI, RET1, TF1)
Nanticoke, Wicomico, Manokin, Big
Annemessex, and Pocomoke rivers
(ET6, ET7, ET8, ET9, ET10)
Tangier Sound (EE3)
Potomac River (LE2, RET2, TF2)
Lower Chesapeake Bay (CBS)
Rappahannock River (LE3, RET3, TF3)
Western Lower Chesapeake Bay (CB6)
Eastern Lower Chesapeake Bay (CB7)
Mobjack Bay (WE4)
York River (LE4, RET4, TF4)
James River (LE5, RETS, TF5)
Mouth of Chesapeake Bay (CBS)
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
19
-------
chapters: Baywide SAV, Habitat Quality, and
River Flow Trends
Baywide SAV Trends
Since the first bay wide SAV survey in 1978,
the total distribution of SAV in Chesapeake Bay
and its tributaries has increased by 52 percent from
16,898 hectares to 25,728 hectares in 1991 (Figure
4, Table 7). The 1991 data represent a 56 percent
achievement of the Tier I SAV distribution resto-
ration goal (46,025 hectares) and a 10 percent
achievement of the Tier III distribution restoration
target (247,658 hectares). Submerged aquatic veg-
etation distribution actually decreased after 1978,
dropping to 15,433 hectares in 1984. Decreases
from 1978 to 1984 occurred predominantly in the
upper Bay segments (Upper Central Chesapeake
Bay, Middle Central Chesapeake Bay, Eastern Bay,
and the Gunpowder, Middle, Patapsco, Magothy,
Severn, Chester, Choptank, Lower Choptank, Lower
Patuxent, and Lower Potomac rivers). These de-
clines suggest that water quality conditions in these
portions of the Bay continued to worsen and af-
fected the remaining SAV populations. Some of the
losses were offset by gains in SAV distribution in
other segments during this time period, notably the
Lower Chesapeake Bay, Eastern Lower Chesa-
peake Bay, Tangier Sound, and the Upper Potomac
River.
Along with the increase in SAV distribution
between 1984 and 1991 was a concomitant increase
in the overall density of many SAV beds. While
38 percent (5,931 hectares) of mapped SAV was
classified as dense (70 to 100 percent coverage) in
1984, by 1991 more than twice as many hectares
of SAV (12,947 hectares or 50 percent of the total)
fit this category (Figure 4, Table 7).
Several significant changes between 1978
and 1991, broadly illustrated in Figure 5 and
Table 8 and described in detail in Chapter 4, are
summarized as follows:
Although SAV increased in distribution
baywide during this period, relatively large
interannual fluctuations in SAV distribu-
tion occurred in many areas throughout the
Bay and its tidal tributaries.
The largest expansion of SAV occurred in
the lower mainstem Bay segments where
SAV populations had not declined as dra-
matically during the 1970s as the upper
mainstem Bay or up-tributary areas. The
SAV beds remaining in these segments
(Western Lower Chesapeake Bay and East-
ern Lower Chesapeake Bay) after the period
of baywide declines may have contributed
to a pool of propagules (i.e., seeds or frag-
ments of vegetation able to form new plants)
whichsupported repopulation of unvegetated
areas.
The rapid spread of SAV in the tidal fresh
portion of the Potomac River has resulted
in the highest levels of SAV abundance in
that river since the early 1900s. Although
the exotic H. verticillata was the dominant
species contributing to this rapid spread,
numerous other native species also occur
with this exotic. Although some declines in
SAV were noted around Washington, DC
since 1989, these losses were offset by the
continued, rapid downriver expansion be-
low Quantico to Aquia Creek.
In the 1980s, R. maritima underwent a sud-
den and rapid expansion in the middle
mainstem Bay, as well as in the lower
Patuxent, Chester, Choptank, and Rappa-
hannock rivers. Subsequent declines occurred
in some of these areas.
Many sections of the Bay and its tidal tribu-
taries remain unvegetated or have very sparse
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
21
-------
Chapter 3: Baywide SAV, Habitat Quality, and River Flow Trends
25000 -
ND ND ND ND ND
78 79 '80 '81 B2 B3 B4 B5
?: 70-100% 40-70% 10-40%
<10%
B7 88 "89 30 31
• No Density Reported
Figure 4. Hectares of SAV by density category for all years for which aerial survey data were available baywide. The
baywide Tier I SAV restoration goal and Tier III SAV restoration target are 46,025 and 247,658 hectares, respectively.
In 1978, density was not recorded for the SAV mapped in the Maryland portion of Chesapeake Bay. ND=No data.
Sources: Anderson and Macomber, 1980; Batiuket al., 1992; Orth et al., 1979,1985,1986,1987,1989,1991, and 1992;
Orth and Nowak, 1990.
Table 7. Hectares of SAV by
Year No Density
Reported
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
ND=No data
8,360
ND
ND
ND
ND
ND
—
—
—
—
ND
—
—
—
Density Category for
<10%
911
ND
ND
ND
ND
ND
2,787
3,227
3,785
3,640
ND
3,331
3,561
3,199
Sources: Anderson and Macomber, 1980; Orth et
Nowak, 1990.
all Years for
10-40%
2,387
ND
ND
ND
ND
ND
2,861
4,111
3,596
3,296
ND
4,350
5,603
4,851
which Aerial Survey
40-70%
4,229
ND
ND
ND
ND
ND
3,854
6,500
3,761
3,585
ND
3,730
3,990
4,731
al., 1979, 1985, 1986,1987, 1989,
Data were Available
70-100%
1,011
ND
ND
ND
ND
ND
5,931
6,135
8,283
9,713
ND
12,836
11,240
12,947
Baywide
Baywide
Total
16,898
ND
ND
ND
ND
ND
15,433
19,974
19,425
20,234
ND
24,247
24,394
25,728
1990, 1991, and 1992; Orth and
22
Trends in the Distribution, Abundance, and Habitat Qualiiy of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 3: Baywide SAV, Habitat Quality, and River Flow Trends
1978 1984 1985 1986 1987 1989 1990 1991
B Upper Bay 0 Middle Bay | Lower Bay
Figure 5. Hectares of SAV by upper, middle, and lower regions of Chesapeake Bay and its tributaries for all years for
which aerial survey data were available baywide.
Sources: Anderson and Macomber, 1980; Orth et al, 1979,1985,1986,1987,1989,1991, and 1992; Orth and Nowak,
1990.
Table 8. Hectares of SAV by Upper, Middle, and Lower Regions of Chesapeake Bay and its Tidal Tributaries for all Years
for which Aerial Survey Data were Available Baywide
Year
Lower
Bay
Middle
Bay
Upper
Bay
Baywide
Total
1978
1984
1985
1986
1987
1989
1990
1991
5,576
5,943
6,129
6,198
6,323
8,019
8,326
9,212
8,291
6,444
10,710
10,454
10,947
13,759
13,706
14,348
3,031
3,046
3,135
2,773
2,964
2,469
2,362
2,168
16,898
15,433
19,974
19,425
20,234
20,247
24,394
25,728
Sources: Anderson and Macomber, 1980; Orth et al., 1979,1985,1986,1987,1989,1991, and 1992; Orth and Nowak,
1990.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
23
-------
Chapter 3: Baywide SAV, Habitat Quality, and River Flow Trends
populations—principally the upper western
shore and Eastern Shore tributaries. Two
major western shore tributaries, the James
and Patuxent rivers, have almost no SAV
throughout their entire length (although an
increase in or e species for several years was
observed in the Patuxent River (see above)).
• Ground survey reports indicated increasing
amounts of Zannichellia palustris in many
areas of the upper Bay, in particular, the
upper western shore tributaries (e.g., the
Severn and Sauth rivers). This species is an
annual which grows and reproduces in spring
and dies by rnid summer. The aerial over-
flights are tiined with the peak growth of
most SAV species in these areas, after the
Z. palustris plants have died for the season.
Beds of this species, therefore, are not mapped
through the aerial survey.
• Ground surveys have confirmed the pres-
ence of remnant SAV populations in small
tidal creeks and tributaries (e.g., the Patuxent
River), suggesting the presence of vegeta-
tive sources or seed banks that could
repopulate riverine populations if water
quality conditions improve..
• The recent changes in SAV populations in
the Chesapea
-------
Chapter 3: Baywide SAV, Habitat Quality, and River Flow Trends
ET1
Increasing Trends
Fluctuating at Higher Levels
Fluctuating at Lower Levels
Decreasing Trends
Little or No SAV
RET2
ET7
ET10
EE3
TF5
CBS
Figure 6. Patterns of SAV distributions from 1971-1991 by Chesapeake Bay Program Segment.
Sources: Anderson and Macomber, 1980; Chesapeake Bay Program, unpublished data b; Orth et al., 1979,1985,
1986, 1987, 1989, 1991, and 1992; Orth and Gordon, 1975; Orth and Nowak, 1990.
Trends in'the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
25
-------
Chapter 3: Baywide SAV, Habitat Quality, and River Flow Trends
Upper Potorm.c River
Tangier Sound
Eastern Lower Chesapeake Bay
*>_»_»_ • IT
l I
D intn O »** Q i
Western Lower Chesapeake Bay
Fiijure 7. Chesapeake Bay segments with increasing trends in SAV.
Sources: Anderson and Macomber, 1980; Chesapeake Bay Program, unpublished data b; Orth et al., 1979,1985,1986,
1987,1989, 1991, and 1992; Orth and Gordon, 1975; Orth and Nowak, 1990.
26
Trends in the Distribution, Abund??::, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 3: Baywide SAV, Habitat Quality, and River Plow Trends
Increases in SAV from 1978 to 1991 were 56
percent in Mobjack Bay, 64 percent in the Eastern
Lower Chesapeake Bay, 85 percent in the Western
Lower Chesapeake Bay, 127 percent in the Lower
Chesapeake Bay, and 232 percent in Tangier Sound.
The relatively larger increases in Lower Chesa-
peake Bay and Tangier Sound segments were
primarily due to the rapid and sudden growth of R.
maritima in the Barren Island-Honga River area.
These areas had almost no SAV in 1978; by 1984,
SAV was reported throughout the area in beds of
various sizes and densities. These areas increased
rapidly to become large, monospecific, and dense
populations of./?, maritima.
Ruppia maritima was the only species re-
ported from the Barren Island-Honga River section,
although Z. marina had historically been abundant
there. While dense populations of Z. marina occur
in the Smith-Tangier Island area, ground surveys
have only occasionally reported this species in
areas north of the Big Annemessex River and Smith
Island.
Dispersal mechanisms for Z. marina are
likely less effective than those for R. maritima,
leading to a slower spread of this species. Ruppia
maritima produces more seeds over a longer time
period—June through October (Silberhorn, unpub-
lished data)—compared to a three to four-week
period from May to early June for Z. marina
(Silberhorn et al., 1983). In addition, R. maritima
can spread from detached post-reproductive shoots
which remain viable after seed release, then float,
and settle to an unvegetated area (Rosenzweig,
unpublished data). Zostera marina reproductive
shoots are terminal and die after seed release al-
though reproductive shoots with viable seeds can
break off, float, and be exported from a bed. Neither
the distance a shoot can float nor the probability
of a viable seed being deposited in an environment
conducive to growth are known. Observations of
one area where a new Z. marina bed apparently
developed from seed indicate that reproductive
shoots can be transported approximately two kilo-
meters with viable seeds (Orth et al., 1992).
Water quality conditions in the lower mainstem
Bay, Tangier Sound, and Mobjack Bay have been
suitable for SAV survival and growth consistently
since the early 1980s (Figures 8-13). Up through
the late 1970s, the data indicate water quality
conditions in these segments fluctuated between
unsuitable (not meeting the SAV habitat require-
ments) and suitable (meeting the SAV habitat
requirements) on an annual basis. Observed im-
provements in water quality correspond directly
with the documented increases in SAV distribution
and abundance.
The only other areas that showed continually
increasing trends in SAV distribution were the
upper (TF2) and middle (RET2) segments of the
Potomac River. These increases resulted, in part,
from the 1982 introduction of H. verticillata and
its subsequent rapid spread over more than 60
kilometers of shoreline in less than ten years. The
ability of fragments of//, verticillata to root, grow
rapidly, and spread allowed this explosive growth
in such a short period. Numerous other species
were reported in the shallower portions of the SAV
beds where they could compete with H. verticillata—
principally M. spicatum, V. americana, H. dubia,
N. guadalupensis, N. gracillima, E. canadensis, N.
minor, C. demersum, Z. palustris, P. pusillus, and
P. pectinatus. The timing of the rapid increases was
also correlated with improvements made to Blue
Plains and other regional wastewater treatment
facilities (Carter and Rybicki, 1986). Total sus-
pended solids and phosphorus loadings were
significantly reduced and nitrification was intro-
duced. Some SAV declines in 1988 around
Washington, DC appeared to be meteorologically
controlled, but losses were offset by the larger
gains in downriver sections. More species have
been reported from this stretch of the Potomac
River than any other segment in the entire Chesa-
peake Bay.
In the upper and middle reaches of the Potomac
River, water quality conditions were just met or
were slightly above several of the SAV habitat
requirements until 1991 (Figures 8-13). There has
been a positive trend of decreasing concentrations
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
27
-------
Chapter 3: Baywide SAV, Habitat Quality, and River Flow Trends
Figure 8. Achievement of the light attenuation coefficient habitat requirements for one-meter restoration by Chesapeake
Bay Program segment (1970 to 1991).
70 72 74 76 78 80 82 84 86 88 90
Northern Chesapeake Bay
Upper Chesapeake Bay
Upper Central Chesapeake Bay
Middle Central Chesapeake Bay
Lower Chesapeake Bay
Western Lower Chesapeake Bay
Eastern Lower Chesapeake Bay
Mouth of Chesapeake Bay
Bush River
Gunpowder River
Middle River
Back River
Patapsco River
Magothy River
Severn River
South/Rhode/West Rivers .
Upper Patuxent River
Middle Patuxent River
Lower Patuxent River
Upper Potomac
Middle Potomac
Lower Potomac
Upper Rappahannock River
Middle Rappahannock River
Lower Rappahannock River
Upper York River
Middle York River
Lower York River
Mobjack Bay
Upper James River
Middle James River
Lower James River
Northeast River
Elk/Bohemia Rivers
Sassafras River
Chester River
Choptank River
Nanticoke River
Wicomico River
Manokin River
Big Annemessex River
Pocomoke River
Eastern Bay
Choptank Embayment
Tangier Sound
KdHR
Not achieved'
KdHR
Fully achieved3
KdHR
Just achieved1
No Kd data for
SAV growing season
1. For tidal fresh and oligohaline segments >2rrr'; for mesohaline and polyhaline segments >1.5m'1. 2. For tidal fresh and oligohaline segments 1.75-2m-'; for mesohaline
and poyhaline segments 1.25-1.5rr'. 3. For tidal fresh and oligohaline segments <1.75nv'; for mesohaline and polyhaline segments <1.25nv'.
Source;: Batiuk et al., 1992; Chesiipeake Bay Program, 1993a and 1993b.
28
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 3: Baywide SAV, Habitat Quality, and River Flow Trends
Figure 9. Achievement of the light attenuation coefficient habitat requirements for two-meter restoration by Chesapeake Bay
Program segment (1970 to 1991).
70 72 74 76 78 80 82 84 86 88 90
C
CD
E
D>
Q>
C/D
0>
p
CD
(0
0>
Q.
co
to
0)
.c
o
CB1
CB2
CB3
CB4
CBS
CB6
CB7
CB8
WT1
WT2
WT3
WT4
WT5
WT6
WT7
WT8
TF1
RET1
LE1
TF2
RET2
LE2
TF3
RET3
LE3
TF4
RET4
LE4
WE4
TF5
RETS
LE5
ET1
ET2
ET3
ET4
ET5
ET6
ET7
ET8
ET9
ET10
EE1
EE2
EE3
Northern Chesapeake Bay
Upper Chesapeake Bay
Upper Central Chesapeake Bay
Middle Central Chesapeake Bay
Lower Chesapeake Bay
Western Lower Chesapeake Bay
Eastern Lower Chesapeake Bay
Mouth of Chesapeake Bay
Bush River
Gunpowder River
Middle River
Back River
Patapsco River
Magothy River
Severn River
South/Rhode/West Rivers
Upper Patuxent River
Middle Patuxent River
Lower Patuxent River
Upper Potomac
Middle Potomac
Lower Potomac
Upper Rappahannock River
Middle Rappahannock River
Lower Rappahannock River
Upper York River
Middle York River
Lower York River
Mobjack Bay
Upper James River
Middle James River
Lower James River
Northeast River
Elk/Bohemia Rivers
Sassafras River
Chester River
Choptank River
Nanticoke River
Wicomico River
Manokin River
Big Annemessex River
Pocomoke River
Eastern Bay
Choptank Embayment
Tangier Sound
Kd HR not achieved Kd HR fully achieved No Kd data for
>0.8m' < 0.8m-' SAV growing season
Sources: Chesapeake Bay Program, 1993a and 19936.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
29
-------
Chapter 3: Baywide SAV, Habitat Quality, and River Flow Trends
I
Figure 10. Achievement of the total suspended solids SAV habitat requirements for one-
Bay Program segment (1970 to 1991).
7C 72 74 76 78 80 82 84 86 88 90
CB1 • ^J ^**
CB2 • . • • « » • ,A \ ^_ \
^mi—-——B_^_^^ 1^^—i—;ta«—• '
CB3
CB4 • • i • i • i i , A ^^^H • ; • ! •
CBS
CB6
CB7
CB8
WT1
WT2
WT3 • • • •
WT4 • • • •
WT5 • • • •
0)
O>
0)
CO
O)
o
CO
(0
Q.
6
meter restoration by Chesapeake
Northern Chesapeake Bay
Upper Chesapeake Bay
Upper Central Chesapeake Bay
Middle Central Chesapeake Bay
Lower Chesapeake Bay
Western Lower Chesapeake Bay
Eastern Lower Chesapeake Bay
Mouth of Chesapeake Bay
Bush River
Gunpowder River
Middle River
Back River
Patapsco River
Magothy River
Severn River
South/Rhode/West Rivers
Upper Patuxent River
Middle Patuxent River
Lower Patuxent River
Upper Potomac
Middle Potomac
Lower Potomac
Upper Rappahannock River
Middle Rappahannock River
Lower Rappahannock River
Upper York River
Middle York River
Lower York River
Mobjack Bay
Upper James River
Middle James River
Lower James River
Northeast River
Elk/Bohemia Rivers
Sassafras River
Chester River
Choptank River
Nanticoke River
Wicomico River
Manokin River
Big Annemessex River
Pocomoke River
Eastern Bay
Choptank Embayment
Tangier Sound
TSSHR
Not achieved
>15 mg/L
TSSHR
Fully achieved
< 10 mg/L
Source;: Batiuk et al., 1992; Chesapeake Bay Program, 1993a and 1993b.
TSSHR
Just achieved
10-15 mg/L
No TSS data tor
SAV growing season
Trends in thp ^jioution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 3: Baywide SAV, Habitat Quality, and River Flow Trends
Figure 11. Achievement of the chlorophyll a SAV habitat requirements for one-meter restoration by Chesapeake Bay Program
segment (1970 to 1991).
70
Northern Chesapeake Bay
Upper Chesapeake Bay
Upper Central Chesapeake Bay
Middle Central Chesapeake Bay
Lower Chesapeake Bay :
Western Lower Chesapeake Bay
Eastern Lower Chesapeake Bay
Mouth of Chesapeake Bay
Bush River
Gunpowder River
Middle River
Back River
Patapsco River
Magothy River
Severn River
South/Rhode/West Rivers
Upper Patuxent River
Middle Patuxent River
Lower Patuxent River
Upper Potomac
Middle Potomac
Lower Potomac
Upper Rappahannock River
Middle Rappahannock River
Lower Rappahannock River
Upper York River
Middle York River
Lower York River
MobjackBay
Upper James River
Middle James River
Lower James River
Northeast River
Elk/Bohemia Rivers
Sassafras River
Chester River
Choptank River
Nanticoke River
Wicomico River
Manokin River
Big Annemessex River
Pocomoke River
Eastern Bay
Choptank Embayment
Tangier Sound
Chlor a HR Chlor a HR
Not achieved Fully achieved
>15^o/L < 10 }io/l
Sources: Batiuk et al., 1992; Chesapeake Bay Program, !993a and 1993b.
Chlor a HR
Just achieved
10-15 ugA.
No Chlor a data lot
SAV growing season
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
31
-------
Chapter 3: Baywide SAV, h abitat Quality, and River Flow Trends
Figure 12. Achievement of the dissolved inorganic nitrogen requirements for one-meter restoration by Chesapeake Bay
Program segment (1970 to 1991).
70 72 74 76 78 80 82 84 86
88
0)
CD
CO
2
D)
2
Q_
CC
03
0)
to
O.I5mg/L <0.10 mg/L 0.10-0.15 mg/L
Batiuk et al., 1992; Chesapeake Bay Program, 1993a and 1993b.
32
Lends in the Distribution, Abundance, and Habitat Quality ot
Suamerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 3: Baywide SAV, Habitat Quality, and River Flow Trends
Figure 13. Achievement of the dissolved inorganic phosphorus SAV habitat requirements for one-meter restoration by
Chesapeake Bay Program segment (1970 to 1991).
70 72 74 76 78 80 82 84 86 88 90
CB1 : V^~*
CB2 • ~A !*i
Northern Chesapeake Bay
Upper Chesapeake Bay
Upper Central Chesapeake Bay
Middle Central Chesapeake Bay
Lower Chesapeake Bay
Western Lower Chesapeake Bay
Eastern Lower Chesapeake Bay
Mouth of Chesapeake Bay
Bush River
Gunpowder River
Middle River
Back River
Patapsco River
Magothy River
Severn River
South/Rhode/West Rivers
Upper Patuxent River
Middle Patuxent River
Lower Patuxent River
Upper Potomac
Middle Potomac
Lower Potomac
Upper Rappahannock River
Middle Rappahannock River
Lower Rappahannock River
Upper York River
Middle York River
Lower York River
Mobjack Bay
Upper James River
Middle James River
Lower James River
Northeast River
Elk/Bohemia Rivers
Sassafras River
Chester River
Choptank River
Nanticoke River
Wicomico River
Manokin River
Big Annemessex River
Pocomoke River
Eastern Bay
Choptank Embayment
Tangier Sound
DIPHR
Not achieved'
OIPHR
Fully achieved3
DIPHR
Just achieved1
No DIP data lor
SAV growing season
1. For tidal fresh, oligohaline, and polyhaline segments >0.02 mg/L; for mesohaline segments >0.01 rhg/L. 2. For tidal fresh, oligohaline, and polyhaline segments 0.015-
0.02 mg/L; for mesohaline segments 0.0075-0.01 mg/L. 3. For tidal fresh, oligohaline, and polyhaline segments < 0.015 mg/L; for mesohaline segments <0.0075 mg/L.
Sources: Batiuk et al., 1992; Chesapeake Bay Program, 1993a and 1993b.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
33
-------
Chapter 3: Baywide SAV, Habitat Quality, and River Flow Trends
of the SAV habitat requirement parameters from compared to the tidal fresh region of the Potomac
1970 to 1991 (Appendix A). River.
Segments with SAV Fluctuating
at High Levels
Seven of the Chesapeake Bay Program seg-
ments were classified as areas in which SAV
distributions exceeded 100 hectares but showed no
consistent trends of either increasing or decreasing
SAV distribution: Northern ChesapeakeBay (CB1),
Eas:ern Bay (EE1), and the Elk/Bohemia (ET2),
Lower Choptank (EE2), Manokin (ET8), Big
Anr emessex (ET9), and Lower Rappahannock (LE3)
rivers (Figures 6 and 14). Three of these segments
(the Manokin, Big Annemessex, and Lower
Rappahannock riven;) were located near or adja-
cenl to those segments that showed consistent
increases in SAV distribution. In two segments
(Eastern Bay and the Lower Choptank River), R.
maritima rapidly increased in distribution in the
mid 1980s but began to decline by 1990. By 1991,
it h^d been reduced to a few scattered beds. The
rapid spread of R. mciritima could be attributed to
its mode of reproduction (high seed production
over a long time periad) and its ability to produce
post-reproductive shoots that contribute to the veg-
etative population. The rapid vegetative growth of
this species was alsc a factor.
The Susquehanra Flats and tidal Susquehanna
River (the Northern Chesapeake Bay segment) are
included in this category. Interestingly, the flanks
of the tidal Susquehanna River below Conowingo
Dam are densely vegetated with a diverse commu-
nity of SAV species. The very large shallow-water
area (Susquehanna Flats) historically supported
one of the Bay's largest SAV communities with
numerous SAV species (Bayley et al., 1978). This
area remains sparsely vegetated with only one species,
(M. I'picatum) recorde d, predominantly from ground
surveys. Also, H. venicillaia has not spread rap-
idly throughout this region as in the Potomac River
and remains in scattered beds along the flanks of
the river. Its spread may be impeded by the slightly
higher salinity water of the Susquehanna Flats
In four of the segments characterized by SAV
distributions fluctuating at high levels (Northern
Chesapeake Bay, Eastern Bay, Lower Choptank
River, and Lower Rappahannock River), water
quality conditions have often just met SAV habitat
requirements (Figures 8-13). In the three Eastern
Shore tributary segments within this category (Elk/
Bohemia, Manokin, and Big Annemessex rivers),
the light attenuation coefficient and total suspended
solids habitat requirements have generally not been
met throughout the 1970 to 1991 data record (Fig-
ures 8 and 10).
Segments with SAV Fluctuating
at Low Levels
Nine of the segments were classified as areas
in which SAV occurred in distributions less than
100 hectares but showed no consistent trends of
either increasing or decreasing SAV distribution
(Upper Chesapeake Bay (CB2), Middle Central
Chesapeake Bay (CB4), Mouth of Chesapeake Bay
(CBS), and the Sassafras (ET3), Gunpowder (WT2),
Middle (WT3), Lower Patuxent (LEI), Lower
Potomac (LE2), and Lower York (LE4) rivers)
(Figures 6 and 15). Similar to the segments with
SAV fluctuating at higher levels, most of these
segments were either mainstem Bay segments or
adjacent to the mainstem Bay. This group included
the lower York River segment where SAV is present
in a very small section of the lower riverine portion;
the lower Potomac River segment where SAV is
absent from almost all of the mainstem river; the
lower Patuxent River segment; the two western
shore tributaries (the Gunpowder and Middle riv-
ers) that have consistently supported some SAV
throughout the 1980s and 1990s; and three (Upper
Chesapeake Bay, Middle Central Chesapeake Bay,
and Mouth of the Chesapeake Bay) of the four
mainstem Bay segments that contain few areas that
could physically support SAV due to exposed
shorelines.
34
Trends in the Distribution, Abundance, and Habitat Quality of
Subnerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 3: Baywide SAV, Habitat Quality, and River Flow Trends
Northern Chesapeake Bay
Elk/Bohemia Rivers
Figure 14. Chesapeake Bay segments with SAV fluctuating at higher levels of abundance.
Sources: Anderson and Macomber, 1980; Chesapeake Bay Program, unpublished data b; Orth et al, 1979,1985,1986,
1987,1989,1991, and 1992; Orth and Gordon, 1975; Orth and Nowak, 1990.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
35
-------
Chapter 3: Baywide SAV, Habitat Quality, and River Flow Trends
Gunpowder Fliver
Q won
Sassafras River
Q »w% Q »*n 0
Upper Chesapeake Bay
.•....•flilfll
Middle Central Chesapeake Bay
Mouth of Chesapeake Bay
Figure 15. Chesapeake Bay segments with SAV fluctuating at lower levels of abundance.
Sources: Anderson and Macomber, 1980; Chesapeake Bay Program, unpublished data b; Orth et al., 1979,1985,1986,
1937,1989,1991, and 1992; Orth and Gordon, 1975; Orth and Nowak, 1990.
36
Trends in the Distribution, Abundance, and Habitat Quality of
Sub Tierged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 3: Baywide SAV, Habitat Quality, and River Flow Trends
Segments with SAV distributions fluctuating
at low levels have had: water quality suitable for
SAV survival and growth but with limited potential
habitat (Middle Central Chesapeake Bay and Mouth
of Chesapeake Bay); water quality conditions
generally suitable for SAV but with limited sources
of propagules necessary for restoration (Lower
Patuxent and Lower Potomac rivers); or water
quality conditions which ranged widely from un-
suitable to suitable for SAV survival and growth
over the 1971 to 1991 data record (Upper Chesa-
peake Bay and the Sassafras, Gunpowder, Middle,
and Lower York rivers) (Figures 8-13).
Segments with Decreasing Trends
Only two of the 45 Chesapeake Bay Program
segments were classified as areas with consistently
decreasing trends in SAV distribution: Upper Central
Chesapeake Bay (CB3) and Chester River (ET4)
(Figures 6 and 16). These segments were flanked
by segments with little or no SAV (Back, Patapsco,
and Magothy rivers) and those with SAV fluctu-
ating at low levels (Upper Chesapeake Bay, Middle
Central Chesapeake Bay, Gunpowder River, and
Middle River). The Upper Central Chesapeake Bay
and Chester River segments have historically sup-
ported some of the largest concentrations of SAV
beds with high species diversity in the middle
Chesapeake Bay, particularly adjacent to Eastern
Neck and Eastern Neck Island. Although six spe-
cies have been reported from this region in recent
years, only R. maritima has been commonly re-
ported in ground surveys. Except for one SAV bed
in a single cove in the lower Chester River, most
beds appeared monospecific.
Water quality conditions meeting the SAV
habitat requirements in the Upper Central Chesa-
peake Bay have fluctuated annually from 1970 to
1991 (Figures 8-13). The water quality in the
adjacent Chester River has been generally unsuit-
able for SAV survival since the mid 1970s (Figures
8-13).
Segments with Little or No SAV
Twenty of the segments have had little SAV
(less than 50 hectares): Bush (WT1), Patapsco
(WT5), Magothy (WT6), Severn (WT7), South,
Rhode, and West (WT8), Choptank (ET5), Upper
Patuxent (TF1), Middle Patuxent (RET1), Middle
James (RETS), and Lower James (LE5) rivers, or
no SAV present since 1978: Back (WT4), North-
east (ET1), Nanticoke (ET6), Wicomico (ET7),
Pocomoke (ET10), Upper Rappahannock (TF3),
Middle Rappahannock (RET3), Upper York (TF4),
Middle York (RET4), and Upper James (TF5) riv-
ers (Figures 6 and 17). Each of the major western
shore tributaries, except the Potomac River, had
two or all three of its segments in this category, with
the upper tidal fresh and middle transition seg-
ments principally unvegetated All other segments
with little or no SAV are smaller tributaries along
the western or eastern shores. Their relatively small
drainage basins encompass not only highly urban-
ized and industrialized areas (i.e., the Bush, Back,
Patapsco, Magothy, Severn, and South rivers), but
areas with intensive agriculture (i.e., the Choptank,
Nanticoke, and Wicomico rivers), activities result-
ing in greater nonpoint source inputs of nutrients
and sediments.
Early ground surveys showed that these smaller
tidal tributaries had supported SAV beds prior to
1971. Since 1971, however, segments with little
or no mapped SAV have had water quality condi-
tions generally unsuitable for SAV survival (Figures
8-13).
During the late 1980s and 1990s, Z. palustris
was reported from several locations by the Citi-
zens' SAV Hunt Program, especially in the Severn
and South rivers. This species is an annual which
grows rapidly in spring from seed3. It then repro-
duces and dies by early summer in these areas. The
species is not detected through the bay wide aerial
survey because these areas are photographed in mid
summer, usually after this species has disappeared
for the season.
3. The precise germination period in Chesapeake Bay is uncertain but may be during late winter.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
37
-------
Chapter 3: Baywide SAV, Habitat Quality, and River Flow Trends
Upper Central Chesapeake Bay
Figure 16. Chesapeat;e Bay segments with decreasing trends.
Sources: Anderson and Macomber, 1980; Orth et al., 1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
38
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 3: Baywide SAV, Habitat Quality, and River Flow Trends
Patapsco River
Bush River
Northeast River
Middle James River
NO SAV:
1. Back River
2. Upper Rappahannock River
3. Middle Rappahannock River
4. Upper York River
5. Middle York River
6. Upper James River
7. Nanticoke River
8. Wicomico River
9. Pocomoke River
Figure 17. Chesapeake Bay segments with little or no SAV.
Sources: Anderson and Macomber, 1980; Chesapeake Bay Program, unpublished data; Orth et al., 1977,1985,1986,
1987,1989,1991, and 1992; Orth and Gordon, 1975; Orth and Nowak, 1990.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
39
-------
Chaptsr 3: Baywide SAV, Habitat Quality, and River Flow Trends
Baywide Water Quality/SAV
Habitat Requirement Patterns
Achievement of the SAV habitat requirements
by year and segment are presented in a series of
f igui es to illustrate bay wide patterns in water quality
(Figures 8-13). Years in which water quality con-
ditions were more than 25 percent lower than the
habi::at requirements a re identified to highlight those
segments which had conditions suitable for SAV
growth and propagation in addition to survival.
Strict application of the SAV habitat requirements
on a met/not met basis results in a loss of valuable
information contained in the two decades of water
qual ty data. Additional insights into habitat qual-
ity fictors contributing to SAV trends are gained
by examining water quality conditions which either
just meet or are well below minimal habitat require-
ments.
Light Attenuation Coefficient
Consistent year- :o-year attainment of the light
atten uation coefficient habitat requirement for one-
meter restoration was limited to the mainstem Bay
(Susquehanna Flats and from the Bay Bridge south
to the mouth of the Bay), the lower reaches of
several major westerr shore tributaries (Patuxent,
Potomac, and Rappahannock rivers), and large
embayments (Mobjack Bay, Eastern Bay, lower
Choptank River, and Tangier Sound) (Figure 8).
The light attenuation coefficient habitat re-
quirement for two-mel er restoration was met during
one or more growing seasons from 1970 to 1991
in the Lower Potomac River, Lower Rappahannock
River, Chester River, Eastern Bay, Upper Central
Chesapeake Bay, Middle Central Chesapeake Bay,
Lower Chesapeake Bay, Western Lower Chesa-
peake Bay, Eastern Lower Chesapeake Bay, and
the Mouth of Chesape.ikeBay segments (Figure 9).
Even in these segments, this habitat requirement
was not met consistently in all years for which data
were available. Only in the lower Bay segments
do SAV beds extend tc the two-meter depth contour
with the exception of the upper Potomac River
where H. verticillata, a canopy-forming species,
can reach similar depths (Batiuk et al., 1992).
Total Suspended Solids
The overall pattern of meeting the total sus-
pended solids habitat requirement is generally similar
to that of the light attenuation coefficient habitat
requirement for one-meter restoration (Figure 10).
The pattern of meeting or not meeting both the light
attenuation and total suspended solids habitat re-
quirements reflects the influence of total suspended
solids concentrations on water column light attenu-
ation. In some segments, however, the light
attenuation coefficient habitat requirement for one-
meter restoration is met but the total suspended
solids habitat requirement is not.
Chlorophyll a
In the mainstem Bay and the major western
shore tidal tributaries and embayments, the chlo-
rophyll a requirement generally has been met
throughout the data record (Figure 11). In all ten
upper western shore tributaries (Bush, Gunpowder,
Middle, Back, Patapsco, Magothy, Severn, South,
Rhode, and West rivers) and several Eastern Shore
tributaries (Northeast, Elk, Bohemia, Sassafras,
Chester, Nanticoke, and Wicomico rivers), the
chlorophyll a habitat requirement has not been met
over most of the 22-year data record.
Dissolved Inorganic Nitrogen
The only general pattern in the dissolved
inorganic nitrogen habitat requirement is that seg-
ments have either consistently met or not met this
requirement over the data record (Figure 12). Some
segments (i.e., the Magothy, Lower York, and
Wicomico rivers, and Eastern Bay) show no con-
sistent pattern over the data record.
Dissolved Inorganic Phosphorus
Water quality has shown a trend from not
meeting (1974 to 1980) to meeting the dissolved
inorganic phosphorus habitat requirement (since
1984) in most areas of Chesapeake Bay and its tidal
40
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 3: Baywide SAV, Habitat Quality, and River Flow Trends
tributaries (Figure 13). Areas where this trend does
not hold include segments of the Patuxent, Potomac,
York, James, Choptank, and Pocomoke rivers.
Baywide Trends in
SAV and River Flow
Submerged aquatic vegetation distribution
patterns have been strongly linked to water quality.
Based on empirical evidence, the habitat require-
ments identify the minimum water quality levels
necessary to support SAV in different sections of
Chesapeake Bay and its tidal tributaries (Batiuk et
al., 1992; Dennison et al., 1993). River flow from
the Susquehanna and Potomac rivers was also chosen
to test whether it is a good indicator of SAV dis-
tribution over time. These two rivers account for
approximately 75 percent of the total freshwater
inflow to the tidal Bay. River flow can integrate
localized rainfall events, minimizing the bias in-
herent in localized rainfall patterns. It is assumed
that higher flow correlates with higher inputs of
sediments and nutrients.
Susquehanna River flow was measured at
Conowingo, Maryland and Potomac River flow
was measured at Little Falls, Virginia. The mean
monthly flow was divided into quartiles by com-
paring each month and year to the overall distribution
of flow for that month from 1950 to 1991. For
example, the mean monthly flow from October,
1952 was compared to the distribution of October
flows from 1950 to 1991. Each monthly flow was
classified as first quartile (minimum to 25th per-
centile), second quartile (>25th percentile to median),
third quartile (> median to 75th percentile), fourth
quartile (>75th percentile to upper extreme), and
upper extreme (>75th percentile+(1.5 x interquartile)
to maximum). The interquartile range, which es-
timates the variability in the data, is the 75th percentile
minus the 25th percentile. The quartile data were
also summarized by year, counting the number of
months from April to October (the SAV growing
season (Batiuk et al., 1992)) that were above the
median and above the 75th percentile. Years with
average flow should have about half of the months
(three or four) above the median. These annual
summaries were graphed and tested for significant
differences (p < 0.05) by decade with the Kruskall-
Wallis one-way Analysis of Variance (ANOVA)
by ranks, using the NPARlWay procedure in SAS
with the Wilcoxon option (SAS Institute, 1990).
Appendix E summarizes the distribution of
flow data for each month from 1950 to 1991 for
the Susquehanna and Potomac rivers. Figures 18
and 19 show the number of months between April
and October that exceeded the median flow (dashed
line) and the 75th percentile of flow (solid line) for
the Susquehanna and Potomac rivers, respectively.
The annual flow pattern in the Susquehanna
data (Figure 18) shows generally average flows in
the 1950s, below average flows in the 1960s (the
1962 to 1966 period was one of the lowest flow
periods in the 42-year data set), above average
flows in the 1970s (the period from 1972 to 1979
was one of the wettest as five of seven months in
every year equaled or exceeded the median flow),
and average flows in the 1980s. This pattern was
statistically significant for the number of months
above the median (Kruskall-Wallis X2 = 10.4, p =
0.016), but not for the number of months above the
75th percentile (Kruskall-Wallis X2 = 4.4, p = 0.2),
which showed less pronounced differences by decade.
For the number of months above the median, the
mean rank by decade was lowest for the 1960s
(13.8) and highest for the 1970s (29.9), while the
other two decades had mean ranks close to the
expected value of 20.5(19.1 for the 1950s and 19.3
for the 1980s).
The Potomac River flow data show patterns
by decade that resemble those in the Susquehanna,
however, the differences were less pronounced
(Figure 19). The flows in the 1960s were not as
consistently low and the flows in the 1970s were
not as consistently high (Figure 17). The differ-
ences between the rivers were most pronounced in
1976 and 1977, when the Susquehanna River had
five months with flows above the median and the
Potomac River had only one month with above-the-
median flows. There were no significant differences
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
41
-------
Chapter 3: Baywide SAV, Habitat Quality, and River Flow Trends
Fi<|ure 18. Susquehanna R ver flow presented as the number of months between April and October (the SAV growing season) within each year
fron 1950 to 1991 in which the mean monthly flow is above the 50th percentile (• • • • •) and the 75th percentile (Errzrrrrr ) of total
rivisr flow.
Sojrce: U.S. Geological Suvey (unpublished data).
Figure 19. Potomac River flew presented as the number of months between April and October (the SAV growing season) within each year from
1950 to 1991 in which the moan monthly flow is above the 50th percentile (• • • • •) and the 75th percentile (tm®*«®tz-x:) of total river
flow
Sou'ce: U.S. Geological Suney (unpublished data).
42
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 3: Baywide SAV, Habitat Quality, and River Flow Trends
among decades in the Potomac River data for the
number of months above the median (Kruskall-
Wallis X2 = 5.7, p =.0.13) or for the number of
months above the 75th percentile (Kruskall-Wallis
X2 = 5.6, p =
The patterns described above suggest that
river flow may be a critical driving force in struc-
turing the SAV populations in Chesapeake Bay. In
the 1950s, SAV populations were flourishing in
most sections of the Bay and its tidal tributaries.
River flow from the Susquehanna and Potomac
rivers during the SAV growing season was normal
with a couple of years of above normal runoff
followed by low runoff years. Submerged aquatic
vegetation continued to flourish in the 1960s. The
1970s showed a major baywide decline in SAV.
This period had the highest river flows and was
marked by eight consecutive years (1972 to 1979)
for which five of the seven growing season months
had flow from the Susquehanna River at or above
the 50th percentile and which included one of the
most significant storms to affect the Chesapeake
Bay—Tropical Storm Agnes. Submerged aquatic
vegetation began to rebound in the 1980s as river
flow returned to normal. Interestingly, the 1980s
flow is punctuated with high and low flow years.
Submerged aquatic vegetation populations poten-
tially could be sustained during higher flow years
if their growth, distribution, and abundance is
maximized during low flow years. Several con-
secutive high flow years may be most detrimental
to SAV populations.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
43
-------
* Regional Trends in SAV Distribution,
Abundance, and Habitat Quality
Historically, SAV in Chesapeake Bay has undergone both site-specific and species-specific
fluctuations in distribution. Past fluctuations, however, were not of the same magnitude as the 1970s
baywide decline which affected all SAV species throughout the Bay (Orth and Moore, 1983a and 1984;
Stevenson and Confer, 1978; Stevenson and Staver, in press). The most notable of these historical
changes were: 1) the decline of Zostera marina in the 1930s (when it also declined worldwide
(Rasmussen, 1977)); 2) the loss of SAV in the Potomac River by the 1930s; 3) the rapid expansion
and subsequent decline of M. spicatum primarily in the upper Bay and Potomac River in the 1950s
and 1960s, displacing many native species (Bayley et al., 1978); and 4) the rapid spread of Hydrilla
verticillata in the tidal fresh portions of the Potomac River in the 1980s (Carter and Rybicki, 1986).
Stevenson and Confer (1978), Orth and Moore (1984), Carter and Rybicki (1986), and Stevenson and
Staver (in press) offer more detailed accountings of many of these changes.
Trends in the Distribution, Abundance, and Habitat Quality of 45
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Northern Chesapeake Bay
The Northern Chesapeake Bay, which in-
cludes the Susquehanna River and Susquehanna
Flats, historically supported dense5 and diverse
SAV beds (Bayley etal., 1978). Prior to the 1960s,
the U.S. Fish and Wildlife Service recognized this
area as one of the most important habitats for
migrating waterfowl on the East Coast (Stewart
1962). Johns Hopkins University scientists exam-
ined long-term historical changes (over the past
1800 years) in SAV populations using seed and
pollen analysis in Furnace Bay (Brush et al., 1981;
Brush and Hilgartner, 1989; Davis, 1985). These
studies showed the presence of SAV throughout
this period until 1972; some species experienced
declines related to initial European settlement and
water use.
Native SAV in this region was affected by
rapid expansion of the exotic, Myriophyllum
spicatum, in the 1950s. This species was first re-
ported in 1881 in the Potomac River near Alexandria,
Virginia6, but remained an inconspicuous member
of the Bay ecosystem until the 1950s (Bayley et al.,
1978; Stevenson and Confer, 1978).
Beginning in the late 1950s and continuing
through the early 1960s, M. spicatum displaced
much native SAV (Bayley et al., 1968 and 1978).
As the M. spicatum population began to decline
around 1962, however, many native species began
to increase in abundance by the late 1960s. Some
dominant and some non-dominant native species
were less abundant, however, and fewer total spe-
cies existed compared to the time before the expansion
of M. spicatum.
Between the late 1960s and 1972, native plants
began to decline once more. By the end of 1972,
they had almost completely disappeared, princi-
pally due to Tropical Storm Agnes in 1972. The
if....
first bay wide aerial survey in 1978 reported 838
hectares, mostly along the flanks of the Susquehanna
River and in a small area in the Susquehanna Flats.
Since 1984, SAV distributions have fluctu-
ated annually between 1,691 hectares (1991) and
2,365 hectares (1986) in the Susquehanna River
and Susquehanna Flats region (Figure 20, Table 9).
The percent of the Maryland Department of Natural
Resources vegetated SAV ground survey stations
has fluctuated between O'and 17 percent in the tidal
5. The term "dense," as used here, should not be confused with the density classification scheme used in the aerial survey.
6. The exact timing of its introduction into the United States is unknown but is likely around the time of its first recorded appearance.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
47
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Northern Chesapeake Bay
CO
"o
3000-1
2500 -
2000 -
1500-
n
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Susquehanna River and Susquehanna Flats region
over the past 21 years with some SAV (3 to 17
percent) reported for most years (Figure 22).
Although the areal extent of SAV includes a
significant portion of the Susquehanna Flats, SAV
density is very sparse (< 10 percent coverage). This
very large area presently supports sparse popula-
tions of one predominant species, M. spicatum.
Anecdotal and ground survey information suggest
that dense and diverse SAV populations once grew
here, but no estimate has been made of the mag-
nitude of this historical bed. The shoreline of this
section (from just below Havre de Grace and Mill
Creek/Furnace Bay to an area approximately two
miles upriver, including the shoreline surrounding
some of the islands) has continuously supported
small but moderate to dense fringing beds of SAV
containing up to six species. Ground surveys by
different groups (in particular Stan Kollar, Harford
Community College) have reported nine species
over the past seven years.
Myriophyllum spicatum has been most fre-
quently found in these fringing beds along with V.
americana. Other species reported are H. dubia, N.
guadalupensis,N. minor, C. demersum,P.perfoliatus,
P. pectinatus, and H. verticillata. Although H.
verticillata has been continuously reported in this
region since 1984 and has expanded to several
beds, it has not developed into the large contiguous
beds presently found in the Potomac River (Kollar,
personal communication).
Since 1984, Stan Kollar of Harford Commu-
nity College has transplanted SAV (primarily V.
americana) into the Susquehanna Flats region (Kollar,
1985,1986,1987, and 1988). The most successful
sites were at Perry Point and Fishing Battery (the
latter was protected by a submerged breakwater).
Water quality at these successful sites is character-
ized by lower levels of turbidity and lower
concentrations of total suspended solids, chloro-
phyll a, and dissolved inorganic phosphorus than
at sites where transplants were not successful (Batiuk
Year
Northern Chesapeake Bay
r Hectares of SAV by ~|
Density Category % of Tier I NofTwl
1 Segment Restoration Restoration
<10% 1040% 40-70% 70-100% Total Goal Goal
70
71
72
73
74
75
76
77
78
79
•80
•81
'82
•83
•84
•85
B5
•87
'00
OO
B9
•90
•91
-
-
2,060
1,921
2,174
2,075
1,850
1,619
1,504
-
53
40
82
41
67
55
50
•
-
27
59
33
20
37
23
14
-
-
41
31
76
92
0
84
123
838
'
2,181
2,051
2,365
2528
1,954
1,781
1,691
27%
-
70%
66%
76%
72%
63%
57%
55%
12%
-i
31%
29%
34%
32%
28%
26%
24%
Table 9. Hectares of SAV by density category and percentage of Tier I SAV
restoration goal (3,101 hectares) and Tier III SAV restoration target (6,974
hectares)arelistedfof 1970to1991 forCBPSegmentCBI (NorthemCheseapeake
Bay).
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al., 1985,
1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
100 -A
717273747576777879H>B1«21B3«485S6WS8«9<90'91
Year (no bar = ground survey data not available)
Figure 22. Percentage of Maryland Department of Natural Resources SAV
Ground Survey Program stations sampled where SAV was observed for CBP
Segment CB1 (Northern Chesapeake Bay). Ground survey data were not
available for 1989 and 1990.
Source: Chesapeake Bay Program, unpublished data c.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
49
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
etal., 1992). These successful sites also had natu- Achievement of the Tier I restoration goal
rally occurring SAV beds both prior to and after (3,101 hectares) has ranged from 55 to 76 percent
the transplanting program. since 1984. Achievement of the Tier III restoration
target (6,975 hectares) has ranged from 24 to 34
Water quality conditions since 1984 have met percent since 1984 (Table 9).
all four of the SAV habitat requirements in the
Susquehanna Flats region (Figure 21). Water quality The lack of expansion of SAV through the
for this segment is characterized by a single moni- Susquehanna Flats is anomalous since dense multi-
toring station located in the navigation channel at species beds of SAV exist along both shorelines of
the mouth of the Susquehanna River. The slight the tidal Susquehanna River and the water quality
dov/nward trend in SAV distribution since 1986, generally seems adequate to support SAV. Patches
as well as the lack o:: increase in bed density, may of SAV do exist throughout the Susquehanna Flats
reflect the inadequacy of a single station to char- but are composed of only one species (M. spicatum).
acterize the water quality of the entire Susquehanna Without the dense SAV beds that once stabilized
Fla:s. More spatially intensive monitoring net- sediments and baffled currents and waves, regular
works have shown significant differences in water disturbance of sediments by wind and waves along
quality conditions across the Susquehanna Flats the long, open fetch may create environmental
(Batiuk et al., 1992). Full restoration of SAV to conditions unsuitable for SAV to recolonize this
potential habitat (down to the two-meter depth area. Also, sedimentary conditions may have changed
contour) is current!} limited by insufficient light since Tropical Storm Agnes in 1972 and this change
penetration. may still be playing a role in preventing the re-
establishment of SAV.
50 Trends in the Distribution, Abundance, and Habitat Quality of
Subnerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Northeast, Elk, Bohemia,
and Sassafras Rivers
The Northeast, Elk, Bohemia, and Sassafras
rivers are the northernmost four of ten tributaries
entering Chesapeake Bay from the Eastern Shore.
The aerial survey reported a small amount of SAV
(zero to 47 hectares) in these rivers between 1978
and 1987, principally near the mouths of the rivers
and in protected coves and shallow embayments.
From a high of five hectares in 1978, no SAV
was reported in the Northeast River by the aerial
survey after 1989 (Figure 23 and Table 10). Sub-
merged aquatic vegetation in the Elk River increased
from 1987 to 1989 (from eight to 198 hectares) and
again in 1990 (364 hectares), principally along the
river's northern shore (Figure 25). The distribution
then decreased to 271 hectares in 1991. Most SAV
beds in the Elk River have been classified as very
sparse (<1 to 10 percent coverage) or sparse (10
to 40 percent coverage), indicating the very patchy
nature of the SAV in this region (Table 11). The
patchy nature of these SAV beds may have led to
underestimating or underreporting SAV distribu-
tion in the late 1970s and early to mid-1980s. No
SAV has been mapped in the Bohemia River except
for one very sparse bed at Town Point at the river
mouth. In the Sassafras River, SAV has been
generally located near the mouth in small beds and
has never exceeded a total of 40 hectares except
in 1989, when the aerial survey reported 91 hect-
ares (Figure 27 and Table 12).
The Maryland Department of Natural Re-
sources ground survey reported SAV in the Northeast
River in only two years between 1971 and 1991
(1979 and 1984) (Figure 29). They reported no
SAV in.the Elk and Bohemia rivers, although some
SAV had been reported in the 1950s and 1960s.
From 1989 through 1991, the Maryland survey
reported rooted SAV (M. spicatuni) inshore of its
unvegetated stations in the Elk River. The survey
also reported SAV in the Sassafras River in 1974,
1981, 1983, 1986, 1989, 1990 and 1991, with the
most recorded in 1990 (Figure 30). Abundant SAV
was found in the Sassafras River in the 1960s by
earlier surveys. Discrepancies between the find-
ings of the aerial survey and the Maryland Department
of Natural Resources ground survey probably re-
sult from the denser SAV beds that grow very close
to shore in areas not checked by survey crews or
the very sparse nature of the beds.
Myriophyllum spicatum and V. americana
were the two species most frequently reported in
the Elk and Sassafras rivers by ground surveys.
Other species reported in ground surveys were P.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
51
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Northeast River
5
CO
"5
jg
to
S
100-
90-
80-
70-
"
60-
50-
40-
30-
20-
10-
n-
ND ND ND ND ND ND ND ND f ND ND ND ND ND 0 0 f=g _f ND 0 0 0
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 "M '85 B6 B7 '88 '89 'SO 91
ED 70-100% D 40-70% 0 10-40% • <10% • No Density Reported
ND = No Data 0 = Area surveyed, no SAV mapped
Figure 23. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment ET1 (Northeast River),
the Tier I SAV restoration goal is seven hectares.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al. 1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
4-
0)
or
*rt
S
2H
c/)
•s
| 1H
(1) (2) (3)
0 0 ND ND 0
1
NO
{— :
ND ND ND ND
Ft
f—
f=.
£2
^
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData Q Kd Q DIP • CHLA • TSS
Rgure 24. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment ET1 (Northeast River).
No SAV habitat requirements met=0; no water quality data available = ND. Sufficient data for the following parameters were not available to calculate
growing season medians: Kd (1971-1974,1979,1981-1984); TSS (1970-1973,1979,1981-1984); CHLA (1970,1972,1973,1979,1981-1984); and
DIP(1970,1972,1973,1979,1981-1984). Numbers of SAV habitat requirements with growing season medians are shown above bars when some
values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
52
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
1000 -f
800-
600-
o
& 400-
200-
Elk/Bohemia Rivers
ND ND ND ND ND ND ND ND
ND ND ND ND ND
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 "91
ND = No Data [^ 70-100% Q 40-70% Q 10-40% | <10% j§ No Density Reported
Figure 25. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment ET2 (Elk/Bohemia
Rivers), the Tier I SAV restoration goal is 467 hectares.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al., 1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
S 4-
«S
a>
•5 3H
o-
o>
cc
>
(A
"5
2H
1-
(3) (3) (3) (3) (3)
0 ONDNDOO 000 0
ND ND ND ND
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = No Data
Kd
DIP
CHLA
TSS
Figure 26. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment ET2 (Elk/Bohemia
Rivers). No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters were not available
to calculate growing season medians: Kd (1971-1975,1981-1984); TSS (1972,1973,1981-1984); CHLA (1972,1973,1981-1984); and DIP (1970,
1972,1973,1979,1981-1984). Numbers of SAV habitat requirements with growing season medians are shown above bars when some values
were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
53
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Sassafras River
o
100-
90-
80-
70-
60-
50-
40-
30-
20-
10-
0
ND ND ND ND ND ND ND ND
ND ND ND ND ND
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 "90 '91
ND = NoData (£] 70-100% Q 40-70% 0 10-40% • <10% • No Density Reported
Figure 27. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment ET3 (Sassafras River),
the Tier I SAV restoration goal is 167 hectares.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al., 1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
5-
i 4
£
I ,
s 3
(3) (3)
ND ND 0 0
(3)
(3)
• ° I 0
ND ND ND ND ND ND
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData Q Kd Q DIP • CHLA • TSS
Figure 28. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment ET3 (Sassafras River).
No SAV habitat requirements met=0; no water quality data available = ND. Sufficient data for the following parameters were not available to calculate
growing season medians: Kd (1971-1975,1977-1984); TSS (1972,1973,1979-1984); CHLA (1972,1973,1979-1984); and DIP (1970,1972,1973,
1979-1984). Numbers of SAV habitat requirements with growing season medians are shown above bars when some values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
54
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
pectinatus,Z. palustris, E. canadensis, C. demersum,
R. maritima, H. dubia, Najas spp., H. verticillata,
and P. crispus.
Since 1 984, Stan Kollar, Harford Community
College, has transplanted SAV (primarily V.
americana) into the Elk and Sassafras rivers (Kollar,
1985, 1986, 1987, and 1988). The most successful
sites were at Elk Neck at the mouth of the Elk River,
and below Ordinary Point along the north shore of
the Sassafras River (with the exception of two sites
adjacent to Betterton). Sites at the mouth of the
Sassafras River had SAV beds of naturally occur-
ringM. spicatumandP. crispus. Repeated transplant
experiments above Ordinary Point were never
successful. Transplanted plots failed in 1989 after
two years of successful growth, although the sur-
rounding natural vegetation survived with no apparent
explanation. At Elk Neck, plots were surrounded
by extensive SAV beds of naturally occurring M.
spicatum. As in the Susquehanna Flats area, water
quality at the successful transplant sites was char-
acterized by lower levels of turbidity and lower
concentrations of total suspended solids, chloro-
phyll a, and dissolved inorganic phosphorus compared
to the unsuccessful transplant sites (Batiuk et al.,
1992).
Northeast River
r Hectares of SAV by — .
Density Category
Year <1
70
•71
/I
72
73
74
75
76
77
78
79
'80
•81
'82
'83
'84
'85
'86
'87
'88
00
$9
•90
•91
Table 10
I0% 10-40% 40-70% 70-100% Total
- ...
.
- ...
...
.
5
.
-
.
-
.
00000
00000
0 <1 <1 <1 3
00 0 <1 <1
00000
00000
00000
%ofTierl % of Tier •
Restoration Restoration
Goal
•
.
.
.
.
71%
•
-
-
-
0%
0%
43%
14%
0%
0%
0%
Goal
"
•
.
„
.
.
<1%
•
-
-
-
0%
0%
<1%
<1%
0%
0%
0%
. Hectares of SAV by density category and percentage of Tier 1 SAV
Water quality conditions in the Northeast,
Elk, Bohemia, and Sassafras rivers have been
unsuitable for SAV survival over the 1970 to 1991
data record, consistently meeting only the dis-
solved inorganic phosphorus habitat requirement
since 1985 (Figures 24, 26, and 28, respectively).
Documented year-to-year fluctuations in SAV
distribution, as well as low overall distribution,
reflect these unsuitable water quality conditions.
Because SAV abundance is very low or ab-
sent in the Northeast River, achievement of the Tier
I restoration goal and the Tier III restoration target
has also remained low (generally zero percent)
(Table 10). Achievement of the Tier I restoration
goal and the Tier III restoration target for both the
Elk and Bohemia rivers had reached 58 percent and
restoration goal (seven hectares) and Tier III SAV restoration target (1,208
hectares) are listed for 1970 to 1991 for CBP Segment ET1 (Northeast River).
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al., 1985,
1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
lOO-i
•0 90-
0)
I80'
O) 70-
0)
£<»-
.2 »-
S 40-
(/>
- 30-
5 20-
OL 10-
s
f\ f\
717273747576777879'80'81182'83'84'85'86'87188'89'9091
Year (no bar = ground survey data not available)
Figure 29. Percentage of Maryland Department of Natural Resources SAV
Ground Survey Program stations where SAV was observed for CBP Segment
ET1 (Northeast River). Ground Survey data were not available for 1971,1989,
and 1990.
Source; Chesapeake Bay Program, unpublished data c.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
55
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Elk/Bohemia Rivers
r Hectares of SAV by — ,
Density Category % of Tier 1 % of Tier III
Segment Restoration Restoration
Year <10% 10-40% 40-70% 70-100% Total Goal Goal
70
71
72
73
74
75
76
77
78 1 <1% <1%
79
•80
•81
•82
•83
"84 8 6 0 0 14 3% <1%
•85 10 36 <1 0 47 10% 2%
•86 <1 3 2 2 8 2% <1%
•87 0 3 5 0 8 2% <1%
•88
•89 102 95 0 1 198 42% 7%
•90 42 322 0 0 364 78% 12%
•91 190 80 0 0 271 58% 9%
Table 11. Hectares of SAV by density category and percentage of Tier I SAV
restoration goal (467 hectares) and Tier III SAV restoration target (2,967
hectares) are listed for 1 970 to 1 991 for CBP Segment ET2 (Elk/Bohemia Rivers).
Sources: Anderson and Macomber, 1 980; Batiuk et al.,1 992; Orth et al., 1 985,
1986, 1987, 1989, 1991 , and 1992; Orth and Nowak, 1990.
9 percent, respectively, in 1991, up from 1 percent
achievement for both tiers in 1978 (Table 11). In
the Sassafras River, SAV abundance was 18 per-
cent and 2 percent of the Tier I restoration goal and
the Tier III restoration target, respectively, in 1991
(Table 12).
Sassafras River
r Hectares of SAV by — ,
Density Category
Segment
Year <10% 10-40% 40-70% 70-100% Total
70
71
72
73
74
75
76
77
78 6
79
'80
'81
'82
'83
'84 0 5 8 7 20
'85 1 17 9 0 27
'86 <1 8 15 9 33
'87 0 0 35 0 35
'88
'89 0 88 3 0 91
•90 <1 39 0 0 40
"91 26 <1 4 0 31
% of Tier I % of Tier B
Restoration Restorabor
Goal Goal
.
-
•
-
-
-
-
•
4% <1%
-
-
-
-
•
13% 1%
16% 2%
20% 2%
21% 2%
•
55% 6%
23% 3%
19% 2%
Table 12. Hectares of SAV by density category and percentage of Tier I SAV
restoration goal (167 hectares) and Tier III SAV restoration target (1,515
hectares) are listed for 1 970 to 1 991 for CBP Segment ET3 (Sassafras River).
Sources: Anderson and Macomber, 1 980; Batiuk et al., 1 992; Orth et al., 1 985,
1 986, 1 987, 1 989, 1 991 , and 1 992; Orth and Nowak,
100 -/
1*
3 80-
g1 ro-
;*:
1 50-
S 40-
m
? 30-
*"1°:,^CU~_C^
1990.
71 72 73 74 75 76 77 78 79 '80 81 B2 83 B4 85 B6 37 B8 B9 W 91
Year (no bar = ground survey data not available)
Figure 30. Percentage of Maryland Department of Natural Resources SAV
Ground Survey Program stations sampled where SAV for CBP Segment (ET3)
(Sassafras River). Ground survey data were not available for 1971,1972, and
1988.
Source: Chesapeake Bay Program, unpublished data c.
56
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Upper Chesapeake Bay and
Upper Central Chesapeake Bay
The Upper Chesapeake Bay and Upper Cen-
tral Chesapeake Bay segments include a large region
of the upper mainstem of the Bay, from below the
Susquehanna Flats south to the Chesapeake Bay
Bridge. Included within these segments is the large
shallow embayment west of Eastern Neck and
Eastern Neck Island and some of the smaller tribu-
taries entering the mainstem.Bay from Pond Creek,
from above the mouth of the Sassafras River south
to just below Swan Point.
Submerged aquatic vegetation has been mapped
continuously in both segments over the course of
the aerial survey, although abundance levels have
fluctuated. Most of the SAV has been reported from
the Eastern Shore side of both segments. Sub-
merged aquatic vegetation beds have been mapped
in Pond, Stillpond, Churn, Worton, Huntington,
and Swan creeks. Since 1987, however, the overall
abundance has declined. Upper Chesapeake Bay
SAV has fluctuated annually from a low of 16
hectares in 1978 to a high of 67 hectares in 1987,
dropping to 29 hectares by 1991 (Figure 31, Table
13).
The largest concentrations of SAV and the
most diverse SAV beds in the Upper Central
Chesapeake Bay segment have historically been in
the shallow embayment between Eastern Neck and
Eastern Neck Island. In 1978, Anderson and
Macomber (1980) listed seven species (M. spicatum,
P. pectinatus, V. americana, Z. palustris, E.
cdnadensis, P. perfoliatus, and R. maritime) in a
large continuous bed along Eastern Neck Island
and Eastern Neck (578 hectares). Only 385 hect-
ares were reported in 1984, increasing to 446 in
1985, but declining in overall distribution and
abundance since 1985. By 1991, only small iso-
lated beds totaling 22 hectares were present (Figure
33, Table 14).
The Maryland Department of Natural Re-
sources ground survey reported no vegetated stations
in the Upper Chesapeake Bay segment. In the
Upper Central Chesapeake Bay segment, they re-
ported SAV during 11 of the past 21 years, with
the percentage of vegetated stations ranging from
0 to 22 percent (Figure 35).
Numerous species have been recorded in both
segments. Diversity has been greatest in the East-
ern Neck embayment. Ruppia maritima was the
most commonly reported species in all years, es-
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
57
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
CO
"o
2»
to
I
100-
90-
80-
70-
60-
50-
40-
30-
20-
10-
0
Upper Chesapeake Bay
ND ND ND ND ND ND ND ND
ND ND ND ND ND
NO = No Data
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 91
|*1 70-100% G 40-70% 0 10-40% | <10% | No Density Reported
Rgure 31. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment CB2 (Upper Chesapeake
Bay), the Tier I SAV restoration goal is 139 hectares.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al, 1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
0)
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData Q Kd Q D|p | CHLA | TSS
Figure 32. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment CB2 (Upper Chesapeake
Bay). No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters were not available
to calculate growing season medians: Kd (1970-1975); TSS (1971 -1976); CHLA (1972-1974); and DIP (1973). Numbers of SAV habitat requirements
with growing season medians are shown above bars when some values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
58
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Upper Chesapeake Bay
Year
70
71
72
73
74
75
76
77
78
79
BO
81
B3
•84
35
•86
IQQ
00
39
•90
•91
r
•
.
0
12
0
23
6
1
1
Hectares of SAVby — ,
Density Category % of Tier I % of Tier IB
' Segment Restoration Restoration
10-40% 40-70% 70-100% Total Goal Goal
-
.
<1
20
6
19
10
17
26
•
.
9
19
5
22
3
<1
2
-
.
6
<1
7
3
0
0
0
16
.
15
52
18
67
19
19
29
12%
.. .
11%
38%
13%
49%
14%
14%
21%
<;%
.
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Upper Central Chesapeake Bay
1000-d
800-
600-
o
& 400-
200-
ND ND ND ND ND ND ND ND
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 90 91
ND = NoData (5] 70-100% D 40-70% Q 10-40% • <10% • No Density Reported
Figure 33. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment CB3 (Upper Central
Chesapeake Bay), the Tier I SAV restoration goal is 817 hectares.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al. 1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData Q «d Q DIP 0 DIN • CHLA • TSS
Figure 34. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment CB3 (Upper Central
Chesapeake Bay). No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters were
not available to calculate growing season medians: TSS (1971,1973) and DIN (1973). Numbers of SAV habitat requirements with growing season
medians are shown above bars when some values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
60
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Year
70
71
72
73
74
75
76
77
78
79
•80
•81
•82
•83
"84
•85
•86
•87
•88
B9
W
•91
r
<10%
-
-
16
95
18
5
-
38
8
0
Upper Central Chesapeake Bay
Hectares of SAV by — ,
Density Category %ofTierl %o»Tierlll
' Segment Restoration Restoration
1
-------
Chapter 4: Regional Trend:; in SAV Distribution, Abundance, and Habitat Quality
Bush, Gunpowder, Middle,
Back, and Patapsco Rivers
These rivers constitute five of the ten tribu-
tari es along the B ay' :> upper western shore. Records
from historical ground surveys documented abun-
dart SAV and numerous species in these tidal
rivers in the late 1950s and early 1960s (Stevenson
anc. Confer, 1978). The Bush River had 15 hectares
or less reported for i'our years of the aerial survey
record, with no SAV reported in 1986 or from 1989
to 1991 (Figure 36, Table 15). From a high of 198
hectares in 1978, SAV in the Gunpowder River
declined to zero hectares in 1986, then increased
to ill hectares in 1991 (Figure 38, Table 16). The
Gunpowder River had SAV present at higher dis-
tribution levels more consistently across the years
of the survey than the other four tributaries, with
SAV beds located principally in Saltpeter, Seneca,
and Dundee creeks.
Submerged aquatic vegetation was more
abundant in the Middle River in 1978 (114 hect-
ares) than in subsequent years when only eight
hectares were reporled by the 1991 aerial survey
(Figure 40, Table 17). Since the bay wide aerial
survey began in 1978, no SAV has been mapped
from Back River (Figure 42, Table 18). A small
amount of SAV was reported in the Patapsco River
in 1978 (52 hectares), primarily at the river mouth
(Figure 44, Table 19). Potamogeton perfoliatus
and V. americana were found in these beds (Ander-
son and Macomber, 1980). After 1978, the aerial
survey recorded no SAV in the Patapsco River.
This region is under one of the most restricted
air ;iones in the Bay ('Aberdeen Proving Grounds),
making it even more difficult to acquire good
photography. These areas have had highly variable
abundances of SAV as reported from the Maryland
Department of Natural Resources ground survey,
indicating that the aurial survey results are still a
good approximation of current abundances.
The Maryland Department of Natural Re-
sources ground survey found no SAV in the Bush
River. Although the Bush River had abundant SAV
in the mid-1960s, especially M. spicatum, much of
the SAV was gone by the late 1960s. The Maryland
ground survey found SAV sporadically abundant
in the Gunpowder and Middle rivers. Ground sur-
vey crews most frequently reported M. spicatum
and V. americana. Submerged aquatic vegetation
was reported in seven of the 15 years surveyed in
the Gunpowder River, with the percentage of veg-
etated stations ranging from 25 to 50 percent (Figure
62
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Bush River
CO
(A
1
DC
100-
90-
80-
70-
60-
50-
40-
30-
20-
10-
n -
•
ND ND ND ND ND ND ND ND ND ND ND ND ND Wj 0 ND 0 0 0
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 91
|>K] 70-100% Q 40-70% 0 10-40% | <10% | No Density Reported
Figure 36. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment WT1 (Bush River),
the Tier 1 SAV restoration target is 24 hectares.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al., 1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
4-
0)
•5 3H
cc
75
!S
CO
I
£
2-
(3)
ND ND ND ND ND ND
(4)
0
ND ND ND ND
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData |~] Kd Q DIP • CHLA • TSS
Figure 37. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment WT1 (Bush River).
No SAV habitat requirements met=0; no water quality data available=ND. Sufficient data for the following parameters were not available to calculate
growing season medians: Kd (1970-1979,1981 -1984); TSS (1970-1975,1979,1981 -1984); CHLA (1970-1975,1979,1981 -1984); and DIP (1970-
1975,1979,1981 -1984). Numbers of SAVhabitat requirements with growing season mediansare shown above bars whensome values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
63
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
46) In the Middle River, SAV was reported in 13
of the 21 years surveyed, with the percentage of
stations ranging from 14 to 57 percent (Figure 47).
Submerged aquatic vegetation was most frequently
obssrved in the same areas indicated by the aerial
survey—Dundee, Saltpeter, and Senecacreeks. Sub-
merged aquatic vegetation was more abundant in
these two rivers over the last 20 years than in the
Back and Patapsco rivers. The Maryland Depart-
ment of Natural Resources ground survey in Back
River has reported no SAV during the 1971 to 1991
datarecord. In the Patapsco River, SAV (V. americana
and two species ofPctamogeton) had been reported
until 1983 (14 percent or less of the stations veg-
etated), but was abssnt thereafter (Figure 48).
The 1990 U.S. Fish and Wildlife Service clam
survey found SAV a: only 10.8 percent of 37 sites
visited in the Gunpowder River (Jorde et al., 1991).
Vallisneria americana was the only species re-
ported.
Ground surveys coupled with the aerial sur-
vey found several SAV species in the Gunpowder
(Satpeter, Seneca, and Dundee creeks) and Middle
rivers, with M. spicatum and V. americana most
commonly cited. Najasguadalupensis,E. canadensis,
C. demersum, P. pectinatus, and R. maritima were
reported less frequently. These surveys often re-
pored SAV from regions not visible on aerial
photographs. It is likely that these beds were nar-
row, fringing the shoreline, or very patchy and did
not produce a distinct image on the aerial photo-
graphs at a scale of 1:24,000.
Documented water quality conditions in all
five tributaries have been unsuitable for SAV survival
for most years since 1970. Only the dissolved
inorganic phosphorus habitat requirement has been
consistently met since 1984 in the Bush River, with
two or less SAV habitat requirement's met in any
one year (Figure 37).
In .he Gunpowder River, all four SAV habitat
requirements were met only in 1985 (probably due
Yea
70
71
72
73
74
75
76
77
78
79
•80
•81
'82
•83
'84
'85
'86
'87
r
<10%
.
•
-
-
-
-
-
-
-
-
-
•
-
-
0
3
0
0
Bush River
Hectares of SAV by — .
Density Category
1 Segment
1040% 40-70% 70-100% Total
.
.
.
.
-
.
-
-
<1
.
-
.
-
.
1102
3 6 0 12
0000
<1 14 0 15
%ofTierl
Restoration
Goal
.
-
•
-
-
-
-
-
4%
-
-
-
-
-
8%
50%
0%
63%
Restoration
Goal
•
• -
-
-
-
-
-
-
<1%
-
-
•
-
.
<1%
<1%
0%
<1%
•89 0 0 000 0% • 0%
•90 0 0 00 0 0% 0%
91 0 0 00 00% 0%
Table 15. Hectares of SAV by density category and percentage of Tier I (24
hectares) SAV restoration goal and Tier III (1,836 hectares) SAV restoration
target are listed for 1970 to 1991 for CBP Segment WT1 (Bush River).
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al., 1985,
1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
to the availability of only two data points from
which to derive a growing season median; see
Appendix B) (Figure 39). Since 1987, only the
dissolved inorganic phosphorus habitat require-
ment has been achieved. Similar to the Gunpowder
River, all four SAV habitat requirements were met
in Middle River only in 1984 (again, probably due
to the availability of only three data points from
which to derive a growing season median; see
Appendix B) (Figure 41). Since 1984, only the
dissolved inorganic phosphorus habitat require-
ment has been met consistently, although the total
suspended solids requirement was also met in five
of seven years. Only one SAV habitat requirement
64
Trends in the Distribution, Abundance,.and Habitat Quality of
Sut merged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Gunpowder River
250 -f
200-
150-1
O
50-
ND ND ND ND ND ND ND ND
ND ND ND ND ND 0
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90
ED 70-100% G 40-70% [7] 10-40% B <10% I No Density Reported
ND = No Data
10-40% B <10% I
0 = Area surveyed, no data mapped
Figure 38. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment WT2 (Gunpowder
River), the Tier I SAV restoration goal is 353 hectares.
Sources: Anderson and Macomber, 1980; Batiuket al., 1992; Orth et al, 1985,1986,1987,1989,1991, and 1992; Orth and Nowack, 1990.
ND ND ND ND
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData Q Kd D DIP • CHLA • TSS
Figure 39. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment WT2 (Gunpowder
River). No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters were not available
to calculate growing season medians: Kd (1970-1975,1977-1979,1981 -1984); TSS (1971,1972,1981 -1984); CHU\ (1970-1973,1979,1981 -1984);
and DIP (1970-1972,1981 -1984). Numbers of SAV habitat requirements with growing season medians are shown above bars when some values
were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
65
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
(or none) was met in any given year in Back River
from 1970 to 1991 (Figure 43). Dissolved inor-
ganic phosphorus was the only SAV habitat
requirement achieved since 1985. With the excep-
tion of 1976, only two or fewer habitat requirements
were achieved in the Patapsco River from 1970 to
1991 (Figure 45). Since 1988, the dissolved inor-
ganic phosphorus habitat requirement has been
consistently met; the total suspended solids habitat
requirement has been met in six of the eight years
fro:n 1984 to 1992,
Achievement of the Tier I restoration goal
and the Tier III resto ration target has been minimal
in these five tributary segments, especially since
1984, due to water quality unsuitable for SAV
survival! With very low and fluctuating abundances
of .SAV, the percert achievement of the Tier I
restoration goal has v aried widely from year to year
in the Bush, Gunpowder, and Middle rivers (Tables
15, 16, and 17).
Since 1978, there has been no measurable
achievement of the Tier I restoration goal in the
Back and Patapsco rivers (Tables 18, and 19). In
all live rivers, achievement of the Tier III restora-
tion targets has been generally below 5 percent and
in most years under 1 percent.
Gunpowder River
r Hectares of SAVby —,
Density Category %ofTferl %ofTierH
' Segment Restoration Restoration
Year <10% 10-40% 40-70% 70-100% Total Goal Goal
70
71
72
73
74
75
76
77
78
79
•80
'81
'82
'83
'84
•85
'86
'87
IQQ
oo
'89
•90
•91
-
-
0
6
0
0
0
1
0
-
-
0
35
0
5
4
2
4
-
-
0
7
0
23
19
57
77
-
-
0
0
0
8
2
27
0
200
-
0
47
0
36
25
87
81
56%
-
0%
13%
0%
10%
7%
25%
23%
6%
-
0%
2%
0%
1%
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Middle River
250
200-
CO
M- 1501
o
50-
ND ND ND ND ND ND ND ND
ND ND ND ND ND
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 91
FJ2J 70-100% Q 40-70% j/2 10-40% | <10% | No Density Reported
ND = No Data 0 = Area surveyed, no data mapped
Rgure 40. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment WT3 (Middle River),
the Tier I SAV restoration goal is 349 hectares.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al, 1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData Q Kd Q DIP • CHLA • TSS
Rgure 41. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment WT3 (Middle River).
No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters were not available to calculate
growing season medians: Kd (1970-1975,1979,1981-1983); TSS (1970-1973,1979,1981-1983); CHLA (1970-1973,1979,1981-1983); and DIP
(1970-1973,1979,1981 -1983). Numbers of SAV habitat requirements with growing season medians are shown above bars when some values were
missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
67
-------
Chapter 4: Regional Irenes in SAV Distribution, Abundance, and Habitat Quality
Yea
70
71
72
73
74
75
76
77
78
79
•80
•81
•82
•83
•84
B5
•86
•87
•88
-89
•90
•91
r
<10%
-
-
-
•
-
-
-
- .
0
26
0
7
-
3
0
0
Middle River
Hectares of SAV ty — ,
Density Category %ofTierl % of IK* III
' Segment Restoration Restoration
1MO% 40-70% 70-100% Total Goal Goal
-
-
-
-
-
-
-
-
0
43
0
4
-
4
2
5
-
-
-
-
-
-
-
-
0
8
0
8
-
1
<'
3
•
- .
-
-
-
•
-
0
0
0
18
-
0
0
0
•
-
113
-
-
-
•
-
0
78
0
37
-
8
3
8
•
-
33%
-
-
-
-
-
0%
22%
0%
10%
-
3%
<1%
2%
-
-
14%
-
-
-
•
-
0%
9%
0%
4%
- .
1%
<1%
1%
Year
70
71
72
73
74
75
76
77
78
79
'80
'81
'82
'83
'84
'85
'86
'87
'88
'89
•90
•91
r
<10%
-
-
0
-
-
-
-
-
0
0
0
0
•
0
0
0
Back River
Hectares of SAV by — i
Density Category % erf Tier 1 %ofTierH
Segment Restoration Restoration
1040% 40-70% 70-100% Total Goal Goal
-
-
0
-
-
-
-
-
0
0
0
0
•
0
0
0
-
-
0
-
-
-
-
-
0
0
0
0
•
0
0
0
•
-
0
-
-
-
-
-
0
0
0
0
-
0
0
0
•
-
0
-
-
•
-
-
0
0
0
0
-
0
0
0
-
-
0%
-
-
-
-
-
0%
0%
0%
0%
-
0%
0%
0%
. •
-
0%
-
-
-
-
-
0%
0%
0%
0%
•
0%
0%
0
Table 17. Hectares of SAV by density category and percentage of Tier I SAV
restoration goal (349 hectares) and Tier 111 SAV restoration target (839 hectares)
are isted for 1970 to 1991 for GBP Segment WT3 (Middle River). In 1979,217
hectares of SAV were mappec through the regional aerial survey of Maryland.
These aerial survey data were included in the calculation of the Tier I restoration
goa, but not in the SAV trend analysis for the reasons described in Chapter I.
Sources: Anderson and Maconber, 1980; Batiuk et al., 1992; Orth et al., 1985,
198 5,1987,1989,1991, and 1992; Orth and Nowak, 1990.
Table 18. Hectares of SAV by density category and percentage of Tier III SAV
restoration target(1,061 hectares) are listed for 1970 and 1991 forCBP Segment
WT4 (Back River). In 1979, two hectares of SAV were mapped through the
regional aerial survey of Maryland. These aerial survey data were included in the
calculation of the Tier I restoration goal, but not in the SAV trend analysis for the
reasons described in Chapter I.
Sources: Batiuk et al., 1992; Chesapeake Bay Program, unpublished data a, b;
Orth et al., 1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
U.S. EPA Headquarters Library
Mail code 3201
1200 Pennsylvania Avenue NW
Washington DC 20460
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
5
y
o
o>
cc
1
Back River
100-
90-
80-
70-
60-
50-
40-
30-
20-
10-
1
'
ND ND ND ND ND ND ND ND 0 ND ND ND ND ND 0 0 0 0 ND 0 0 0
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 91
EH 70-100% n 40-70% 0 10-40% • <10% • No Density Reported
ND = No Data 0 = Area surveyed, no SAV mapped
Figure 42. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment WT4 (Back River),
the Tier I SAV restoration goal is two hectares.
Sources: Anderson and Macomber, 1980: Batiuk et al., 1992; Orth et al., 1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
4>
v>
•5 sH
a
cc
'CD
en
•5
Jr. H
o-
(3)
(3) (3) (3)
000
ND ND ND
(1)
0
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData Q Kd Q DIP • CHLA • TSS
Rgure 43. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment WT4 (Back River).
No SAV habitat requirements met=0; no water quality data available=ND. Sufficient data for the following parameters were not available to calculate
growing season medians: Kd(1979,1981-1984);TSS(1970-1973,1979,1981-1984);CHLA(1979,1981-1983);andDIP(1979,1981-1984). Numbers
of SAV habitat requirements with growing season medians are shown above bars when some values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
69
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Patapsco River
§
CO
o
£
100-
90-
80-
70-
60-
50-
4O-
30-
20-
10-
n -
*
ND ND ND ND ND ND ND ND 1 ND ND ND ND ND 0 0 0 0 ND 0 0 0
^p _ . ,
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
[J3 70-100% Q 40-70% 0 10-40% | <10% • No Density Reported
ND = No data
0 = Area surveyed, no SAV mapped
Figure 44. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment WT5 (Patapsco River),
the Tier I SAV restoration goal is 53 hectares.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al., 1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
1 5H
(A
0>
4-
3-
2-
I 1-1
0
ND ND
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = No Data Q Kd 0 DIP • CHLA • TSS
Figure 45. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment WT5 (Patapsco River).
No SAV habitat requirements met=0; no water quality data available=ND. Sufficient data for the following parameters were not available to calculate
growing season medians: Kd(1972-1975,1977,1981-1983); TSS (1970-1973,1982,1983); CHLA(1972,1973,1981-1983);DIP(1970-1973,1981-
1983); and DIN (1972,1973,1981 -1983). Numbers of SAV habitat requirements with growing season medians are shown above bars when some
values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
70
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Patapsco River 100
r Hectares of SAV by—, •§ *»
Density Category %ofTnrl % of Twin « eo-
Segment Restoration Restoration §> K-
Year <10% 1040% 40-70% 70-100% Total Goal Goal > «,.
70 .... o 50-
71 |«-
72 | 30-
73 - g »•
74 . o. ,o-
75
76
Figure '
78 52 96% 4% Ground
79 Segmen
•go ..... . . Source:
'81
'82 100-
•83 -a 90-
'84 0 0 0 0 0 0% 0% 5 80-
'85 0 0 0 0 0 0% 0% §> 70-
•86 0 0 00 0 0% 0% ^ 60-
'87 0 0 000 0% 0% | 50-
'88 | 40-
•89 0 0 0 0 0 0% 0% £ 30-
•90 0 0 00 0 0% 0% j> 20-
"91 0 0 0 0 0 0% 0% ^ 10-
n-
f
f\ r
.
IJ
•f ifl
_.___• _1 \— \W
j¥m|] Jll
/vr^pfl >•>•>• _^B/^p(^B>fl/^iV s u4*-^L f^^~^r^T~^^
717273747576777879'80'81'82183B4'85'86'87188'899091
Year (no bar = ground survey data not available)
17. Percentage of Maryland Department of Natural Resources SAV
Survey Program stations sampled where SAV was observed for CBP
tWT3 (Middle River).
Chesapeake Bay Program, unpubl shed data c.
-fW —
Table 19. Hectares of SAV by density category and percentage of Tier I SAV
restoration goal (53 hectares) and Tier III SAV restoration target (1,452
hectares) are listed for 1970 to 1991 for CBP Segment WT5 (Patapsco River).
In 1979, two hectares of SAV were mapped through Maryland's regional aerial
survey. These data were included in the calculation of the Tier I restoration goal,
but not in the SAV trend analysis for the reasons described in Chapter I.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al.,1985,
1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
71 72 73 74 75 76 77 78 79 BO '81 B2 B3 84 85 86 B7 ?8 89 '90 91
Year (no bar = ground survey data not available)
Figure 48. Percentage of Maryland Department of Natural Resources SAV
Ground Survey Program stations sampled where SAV was observed for CBP
Segment WT5 (Patapsco River). Ground survey data were not available for 1975.
Source: Chesapeake Bay Program, unpublished data c.
80-
I
g>™-
60-
2 40-
(0
71 72 73 74 75 76 77 78 79 H) 81 ffi 83 W 85 86 B7 B8 B9 90 91
Year (no bar = ground survey data not available)
Figure 46. Percentage of Maryland Department of Natural Resources SAV
Ground Survey Program stations sampled where SAV was observed for CBP
Segment WT2 (Gunpowder River). Ground survey data were not available for
1971,1972,1975,1989, and 1990.
Source: Chesapeake Bay Program, unpublished data c.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
71
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Chester River
Scientists have long studied the distribution
of S'.AV in the Chester River, a tributary to the Bay
on the Eastern Shore Several surveys prior to 1971
provide excellent documentation on its historical
SA V distribution (Stevenson and Staver, in press).
The bay wide aerial survey reported more SAV
in 1978 than in subsequent years, with concentra-
tions of SAV primarily along the western shore and
in Grays Inn and Langford creeks (Figure 49, Table
20). Less than one-half of the SAV reported in
1978 (1,072 hectares) was present in 1984 (417
hectares); levels declined further in 1990 to their
lowest level (33 hectares). Most of the reported
SAV beds grew along the western shore of the river,
principally adjacent to Eastern Neck and Eastern
Neck Island and in Grays Inn and Langford creeks.
Much of the remaining SAV in 1991 (35 hectares)
was located in Eastern Neck Narrows, between
Eastern Neck and Eastern Neck Island. In addition,
SAV has persisted in Robin Cove on the western
shore.
The Maryland Department of Natural Re-
sources ground survey found SAV occurring more
consistently over the years in this river than in any
oth;r section of the Bay (Figure 51). Submerged
aquatic vegetation was more abundant in the 1970s
thai the 1980s. The overall pattern of change re-
corded by the ground survey since 1984 is similar
to tiat documented by the aerial survey (Figure 49).
The Maryland Department of Natural Resources
ground survey recorded only two species in 1989
(R. maritima and P. perfoliatus) and one species
in 1991 (R. maritima), whereas, the ground surveys
associated with the aerial survey reported six spe-
cies in both years (Z palustris, P. perfoliatus, P.
pectinatus, E. canadensis, M. spicatum, and R.
ma ntima).
The 1990 U.S. IFish and Wildlife Service clam
survey found SAV at only 1.2 percent of the 253
sites visited (Jorde et al., 1991). Zannichelliapalustris
was the only species reported.
Ruppia maritima and P. perfoliatus were most
commonly reported from several areas in the Chester
River. In addition, M. spicatum, E. canadensis, P.
pectinatus, and Z. palustris were found less fre-
quently. All six species were reported in Robin
Cove in 1991.
Water quality in the Chester River was un-
suitable for SAV survival over the 1970 to 1991
data record. Only in 1984 were four of the five SAV
72
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Chester River
2000-ft
1600-
M_ 1200-
o
tn
£
&
CD
800 J
400-
ND ND ND ND ND ND ND ND I I ND ND ND ND ND
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 91
ND = NoData ^ 70-100% Q 40-70% E2 10-40% • <10% • No Density Reported
Figure 49. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment ET4 (Chester River),
the Tier I SAV restoration goal is 1,506 hectares.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al., 1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
E
"o
2-
1-
(0 (D (*)
0 0 ND ND 0
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData Q Kd D DIP 0 DIN • CHLA • TSS
Figure 50. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment ET4 (Chester River).
No SAV habitat requirements met=0; no water quality data available = ND. Sufficient data for the following parameters were not available to calculate
growing season medians: Kd (1970-1975,1979,1982,1983); TSS (1972,1973,1982,1983); CHLA (1970-1973,1982,1983); DIN (1970-73,1982,
1983); and DIP (1970-1973,1982,1983). Numbers of SAV habitat requirements with growing season medians are shown above bars when some
values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
73
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Chester River
• Hectares of SAV by — i
Density Category % of Tier 1 % of Tier III
Segment Restoration Restoration
Year <10% 10-40% 40-70% 70-100% Total Goal
70
71
72
73
74
75
76
77
Goal
.
-
-
-
-
-
-
-
78 1,074 71% 18%
79
"81
B2
"83
.
-
habitat requirements met; three or fewer SAV habi-
tat requirements were met for all other years (Figure
50). During the most significant decline in SAV
distribution (1985 to 1991), the light attenuation
habitat requirement was generally not met. In 1 986
and 1988, no SAV habitat requirements were met.
The SAV decline since 1984, along with the virtual
absence of SAV in the Chester River by 1991,
indicates that water quality conditions were unsuit-
able for SAV survival since 1984.
Achievement of the Tier I restoration goal
and the Tier III restoration target in the Chester
River was greatest in 1978 (71 percent and 18
percent, respectively) and declined to its lowest
levels in 1990 (2 percent and <1 percent, respec-
tively) (Table 20).
•84 <1 59 149 209 418 28% 7%
•85 33 56 177 106 372 25% 6%
B6 4 45 67 48 164 11% 3%
•87 3 61 87 137 288 19% 5%
38
-
•89 24 15 30 6 75 5% 1%
•90 5 6 21 1 33 2% <1%
"91 0 2 30 2 34 2% <1%
Table 20. Hectares of SAV by density category and percentage of Tier I SAV
restoration goal (1,506 hectares) and Tier III SAV restoration target (5,812
hectares) are listed for 1 970 to 1 991 for CBP Segment ET4 (Chester River).
Sources: Anderson and Macomber, 1 980; Batiuk et al., 1 992; Orth et al., 1 985,
1 986, 1 987, 1 989, 1 991 , and 1 992; Orth and Nowak. 1 990.
100 -/
•0 90-
o 80-
70-
>60-
C JQ
3 40- 1 — . — .
tn • • i^rl^rl
= 30* ~WnWWm \ J\
1 20" Uiju.
5 ! J^]JJiJJJJJiJjrij4
'
EG
71 72 73 74 75 76 77 78 79 BO B1 B2 33 W B5 36 87 38 B9 90 91
Year (no bar = ground survey data not available)
Figure 51. Percentage of Maryland Department of Natural Resources SAV
Ground Survey Program stations sampled where SAV was observed for CBP
Segment ET4 (Chester River). Ground survey data were not available for 1971,
1972, and 1988.
Source: Chesapeake Bay Program, unpublished data c.
74
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Magothy, Severn, South,
Rhode, and West Rivers
These five rivers constitute the remaining
upper western shore tributaries. Since 1984, SAV
has been nearly absent in all five tributaries, with
no more than ten hectares mapped through the
aerial survey in any one year (Figures 52, 54, and
56). Significantly more SAV was found in each
tributary in 1978: 146 hectares in the Magothy
River, 136 hectares in the Severn River, and 78
hectares in the South, Rhode, and West rivers
combined (Tables 21, 22, and 23).
The Maryland Department of Natural Re-
sources ground survey recorded a greater percentage
of vegetated stations in the Magothy and Severn
rivers in the 1970s. Since 1982, no stations with
vegetation were reported except in 1984 and 1991
in the Magothy River (29 percent and 8 percent,
respectively) and in 1983 in the Severn River (8
percent) (Figures 58 and 59, respectively). The
Maryland ground survey recorded the presence of
SAV (14 percent) in only one year (1976) in the
South, West, and Rhode rivers (Figure 60). The
same species were recorded by the other ground
surveys (C. demersum, Z. palustris, P. perfoliatus,
P. pectinatus, and R. maritima).
The 1990 U.S. Fish and Wildlife Service clam
survey found SAV at only 0.9 percent of the 109
sites visited (Jorde et al., 1991). Zannichelliapalustris
was the only species reported.
Ground surveys have reported SAV in all
these tributaries with C. demersum, Z. palustris, P.
perfoliatus, P. pectinatus, and/?, maritima recorded.
In particular, Z. palustris was recorded frequently
through the Citizens' SAV Survey in 1991, espe-
cially in the South River.
Water quality in these five tributaries, as with
the other upper western shore tributaries, has been
consistently unsuitable for SAV survival over the
1970 to 1991 data record. All five SAV habitat
requirements were met only in the Magothy River
in 1987 (Figure 53). In the Severn River, four of
the five SAV habitat requirements were met be-
tween 1986 and 1988 and again in 1991 (Figure 55).
In most years, no more than two or three of the SAV
habitat requirements were met in either the Magothy
or Severn rivers. Within the South, Rhode, and
West rivers, no more than two SAV habitat require-
ments were met in most years of the data record
(Figure 57).
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
75
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Magothy River
250
200-
150 H
o
100-
50-
ND ND ND ND ND ND ND ND
ND ND ND ND
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
EJ] 70-100% n 40-70% [2 10-40% I <10% • No Density Reported
ND = No data
0 = Area surveyed, no SAV mapped
Figure 52. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment WT6 (Magothy River),
the Tier I SAV restoration goal is 240 hectares.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al., 1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
I
I
•5
5-
4-
3-
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData Q Kd Q DIP 0 DIN • CHLA • TSS
Figure 53. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment WT6 (Magothy River).
No SAV habitat requirements met=0; no water quality data available = ND. Sufficient data for the following parameters were not available to calculate
growing season medians: Kd(1970-1975,1979,1981-1984); TSS (1970-1973,1979,1981-1984); CHLA (1970-1973,1979,198M 984); DIP (1970-
1973,1979,1981 -1984); and DIN (1970-1973,1979,1981 -1984). Numbers of SAV habitat requirements with growing season medians are shown
above bars when some values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
76
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Year
70
71
72
73
74
75
76
77
78
79
"80
•81
•82
B3
•84
'85
"86
•87
tOO
00
'89
•90
•91
r
<10%
.
-
-
-
-
-
-
-
-
-
-
-
-
-
0
0
0
0
0
0
0
Magothy
Hectares of SAV by —
Density Category
1(MO%
.
-
-
-
-
-
-
-
-
-
-
-
-
-
4
<1
<1
0
0
0
0
40-70% 70-100%
.
-
-
-
-
-
-
-
-
-
-
-
-
-
5 <1
4 <1
<1 3
<1 0
0 0
0 0
0 0
River
Segment
Total
.
-
-
-
-
•
-
-
146
-
-
-
•
-
10
6
5
<1
0
0
0
% of Tier I % of Tier III
Restoration Restoration
Goal Goal
.
-
-
-
-
-
-
-
61% 17%
-
-
-
-
-
4% 1%
2% <1%
2% <1%
<1% <1%
0% 0%
0% 0%
0% 0%
After 1978, achievement of the Tier I resto-
ration goal and the Tier III restoration target has
not been above 4 percent and 1 percent, respec-
tively, in the Magothy, Severn, South, West, and
Rhode rivers (Tables 21, 22, and 23).
Table 21. Hectares of SAV by density category and percentage of Tier I SAV
restoration goal (240 hectares) and Tier III SAV restoration target (838 hectares)
are listed for 1970 to 1991 for CBP Segment WT6 (Magothy River). In 1979,192
hectares of SAV were mapped through the regional aerial survey of Maryland.
These aerial survey data were included in the calculation of the Tier I restoration
goal, but not in the SAV trend analysis for the reasons described in Chapter I.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al., 1985,
1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
100-/
S.
71 72 73 74 75 76 77 78 79 BO «1 'SZ S3 84 B5 36 87 B8 39 90 91
Year (no bar = ground survey data not available)
Figure 58. Percentage of Maryland Deparment of Natural Resources SAV
Ground Survey Program stations sampled where SAV was observed for CBP
Segment WT6 (Magothy River). Ground survey data were not available for 1971,
1972,1975,1989, and 1990.
Source: Chesapeake Bay Program, unpublished data c.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
77
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Severn River
250
200-
150 H
o
1
|,ooH
50-
ND ND ND ND ND ND ND
ND ND ND ND 0
0 ND 0
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90
[£i] 70-100% G 40-70% ¥2 KMO% • <10% H No Density Reported
ND = No data
0 = Area surveyed, no SAV mapped
Figure 54. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment WT7 (Severn River),
the Tier I SAV restoration goal is 189 hectares.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al., 1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
cr
01
QC
5-
4-
3-
en
•5
0>
.0 1 -
(4) (4)
(4)
(1) d) (2) (D (4)
00000
NO ND ND ND ND ND
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData Q] Kd Q DIP 0 DIN • CHLA • TSS
Figure 55. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment WT7 (Severn River).
No SAV habitat requirements met=0; no water quality data available = ND. Sufficient data for the following parameters were not available to calculate
growing season medians: Kd(1970-1976,1978-1984); TSS (1970-1973,1979-1984); CHLA(1973,1979-1984); DIP (1970,1971,1979-1984); and
DIN (1970-1973,1979-1984). Numbers of SAV habitat requirements with growing season medians are shown above bars when some values were
missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
78
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
South/Rhode/West Rivers
<
"o
100-rl
90-
80-
70-
60-
40-
30-
20-
10-
0
ND ND ND ND ND ND ND ND
ND ND ND NO ND 0
0 ND 0 0
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 W "91
ND = NoData E3 70-100%
40-70%
ND = No data
10-40% | <10% | No Density Reported
0 = Area surveyed, no SAV mapped
Rgure 56 Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment WT8 (South/Rhode/
West Rivers), the Tier I SAV restoration goal is 78 hectares.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al., 1985, 1986, 1987, 1989, 1991, and 1992; Orth and Nowak, 1990..
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87
No Data Fl Kd f] D|p F/l DIN • CHLA •
'88 '89
TSS
'90 '91
Rgure 57. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment WT8 (South/Rhode/
West rivers). No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters were not
available to calculate growing season medians: Kd (1971 -1975,1979,1981 -1983); TSS (1971 -1973,1979,1981 -1983); CHLA (1973,1979,1981 -
1983); DIP (1971,1973,1979,1981-1983); and DIN (1970-1973,1979,1981-1983). Numbers of SAV habitat requirements with growing season
medians are shown above bars when some values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
79
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Severn River
r Hectares of SAV by
Density Category
Year <10
70
71
72
73
74
75
76
77
78
79
BO
81
82
•83
B4 0
•85 0
•86 0
87 0
'88
•89 0
"90 0
•91 0
Table 22.
restoration
% 1(MO%
-
-
.
.
.
„
.
-
-
-
-
-
-
0
0
o
0
0
0
0
40-70%
-
-
.
.
.
„
.
.
-
-
-
-
-
-
0
0
~4
0
-
0
0
0
1
70-100%
-
-
.
.
.
.
.
.
-
-
-
-
-
-
0
0
o
0
-
0
0
0
Segment
Total
-
-
„
.
.
_
.
.
136
-
-
-
-
-
0
0
-4
0
.
0
0
0
% of Tier I % of Tier III
Restoration Restoration
Goal
-
-
.
.
.
„
.
72%
-
-
-
-
-
0%
0%
^1°/
0
0%
.
0%
0%
0%
Goal
-
-
m
_
.
m
m
15%
-
-
-
-
-
0%
0%
-40/
°
0%
-
0%
0%
0%
Hectares of SAV by density category and percentage of Tier I SAV
noal M 89 hectares! anri Tier III SAV restoration tarnet (RM hectares)
South/Rhode/West Rivers
r Hectares of SAV by — ,
Density Category
Segment
Year <10% 10-40% 40-70% 70-100% Total
70
71
72
73
74
75
76
77
78 78
79
'80
81
'82
'83
'84 0 0 000
'85 <1 0 <1 1 3
'86 0 0 <1 0 <1
'87 0 0 000
'88
'89 0 0 000
i/yi on n n o
aU U U U U U
WOO 000
% of Tier 1 % of Tier III
Restoration Restoration
Goal Goal
m
_
.
-
-
-
-
100% 4%
•
-
.
.
.
0% 0%
4% <1%
1% <1%
0% 0%
"
0% 0%
AO/ AO/
Uvo U7o
0% 0%
are listed for 1970 to 1991 for CBP Segment WT7 (Severn River). In 1979,130
hectares were mapped through the regional aerial survey of Maryland. These
aerial survey data were included in the calculation of the Tier I restoration goal,
but not in the SAV trend analysis for the reasons described in Chapter I.
Sources: Anderson and Macomber, 1980;Batiuketal.,1992;Orthetal., 1985,
1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
Table 23. Hectares of SAV by density category and percentage of Tier I SAV
restoration goal (78 hectares)andTierlllSAVrestorationtarget(1,970hectares)
are listed for 1970 to 1991 for CBP Segment WT8 (South/Rhode/West Rivers).
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et a!., 1985,
1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
7172737475'7877787B'80'81«WW85W87B8W90W
Year (no bar = ground survey data not available)
Figure 59. Percentage of Maryland Department of Natural Resources SAV
Ground Survey Program stations sampled where SAV was observed for CBP
Segment WT7 (Severn River). Ground survey data were not available for 1972
and 1975.
Source: Chesapeake Bay Program, unpublished data c
Percent Stations Vegetated
S88SS8S888
f
—
_IJ
71 72 73 74 75 76 77 78 79 BO W B2 B3 84 B5 W B7 B8 B9 90 91
Year (no bar = ground survey data not available)
Figure 60. Percentage of Maryland Department of Natural Resources SAV
Ground Survey Program stations sampled where SAV was observed for CBP
Segment WT8 (South/Rhode/West Rivers).
Source: Chesapeake Bay Program, unpublished data c.
80
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Eastern Bay
The Eastern Bay segment extends east of a
line extending from Kent Point at the southern tip
of Kent Island south to Tilghman Island. This
segment also includes the Miles and Wye rivers and
the many small tidal creeks and rivers entering
Eastern Bay.
In the first bay wide survey (1978), 1,440
hectares of SAV were mapped in Eastern Bay. This
number represented a large proportion of the SAV
in the entire mid-Bay area at that time (Figure 61,
Table 24). By 1984, SAV distribution had dropped
dramatically with only 89 hectares recorded, but it
had increased to 899 hectares by 1987. By 1991,
SAV abundance again had declined with only 68
hectares reported. Submerged aquatic vegetation
was most abundant during the 1980s on the western
side of Eastern Bay along the shores of Kent Island,
Cox Creek, Crab Alley Bay, Prospect Bay, lower
Miles River, and Parson Island.
The Maryland Department of Natural Re-
sources ground survey reported consistently high
percentages of vegetated stations in the early 1970s,
with these percentages declining in the late 1970s
(Figure 63). Between 1980 and 1991, the percent-
age of vegetated stations fluctuated widely reaching
the second highest level of the 21 -year survey in
1987 (47 percent) and then declining to the survey' s
lowest levels in 1989 (0 percent), 1990 (2 percent),
and 1991 (9 percent). The patterns of SAV change
documented here for the 1980s and early 1990s
parallel the distribution patterns reported through
the aerial survey, especially with the rapid spread
(1985 and 1987) and subsequent decline of R.
maritima (1990 and 1991).
Davis (1985) sampled Leeds Creek in 1979
for SAV seeds. This creek was extensively sampled
for SAV seeds in 1977 and 1978 (Davis, unpub-
lished data). Seeds of three species (Z. palustris,
P. pectinatus, and R. maritima) were found. Their
seeds were collected more frequently along the
creek margins than in the center of the creek.
The 1990U.S. Fish and Wildlife Serviceclam
survey found SAV at only 9.9 percent of the 354
sites visited in Eastern Bay (Jorde et al., 1991).
Zannichellia palustris was the only species re-
ported.
Ruppia maritima has been the dominant spe-
cies reported throughout this segment since the
1978 aerial survey. The 1986 and 1987 ground
surveys documented R. maritima throughout East-
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
81
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Eastern Bay
2000-f1
1600-
1200-
o
800-
400-
ND ND ND ND ND ND ND
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData ^ 70-100% Q 40-70% V~\ 1040% • <10% • No Density Reported
Figure 61. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment EE1 (Eastern Bay),
the Tier I SAV restoration goal is 2,474 hectares.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al., 1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
70 71 72 73 74 75 76 '77 78 79
ND = NoData D Kd Q DIP [
0 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
DIN • CHLA • TSS
Figure 62. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment EE1 (Eastern Bay).
No SAV habitat requirements met=0; no water quality data available = ND. Sufficient data for the following parameters were not available to calculate
growing season medians: Kd (1970-1975,1979,1981 -1983); TSS (1970-1973,1979,1981 -1983); CHLA (1972,1973,1979,1981 -1983); DIP (1972,
1973,1979,1981 -1983); and DIN (1970-1973,1979,1981 -1983). Numbers of SAV habitat requirements with growing season medians are shown
above bars when some values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
82
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Eastern Bay
ern Bay, including numerous areas where SAV
r Hectares of SAV by — • beds were not mapped through the aerial survey.
Density Category %ofTierl %ofTierlll Many of these areas were most likely small fringing
Segment Restoration Restoration
Year <10% 10-40% 40-70% 70-100% Total Goal
70
71
72
73
74
75 ...
76
77
Goal
m
.
.
.
-
-
-
-
78 1,439 58% 16%
79
BO
«1
"82
•33 - ...
-
-
-
•84 4 23 57 4 88 4% <1%
•85 10 188 114 88 400 16% 5%
•86 8 152 73 22 255 10% 3%
•87 145 151 302 301 899 36% 10%
•88
-
•89 115 602 64 52 833 34% 9%
"90 87 209 89 5 390 16% 4%
•91 20 39 3 6 68 3% <1%
beds that were not visible from the aerial photog-
raphy, but they indicated the widespread occurrence
of this species during those few years. The ground
surveys also showed the rapid decline of SAV
indicated by the aerial survey. Although several
other species were documented (Z. palustris, P.
perfoliatus, and P. pectinatus), their reported oc-
currence was much less than R. maritima.
Water quality for Eastern Bay met all five
SAV habitat requirements from 1985 to 1988 and
at least four of the five SAV habitat requirements
between 1984 and 1991 (Figure 62). Rapid fluc-
tuations of SAV in this segment even while the
water quality seemed suitable (based on the SAV
habitat requirements) remains problematic. A single
station, located in the middle of Eastern Bay, was
used to characterize 1984 to 1991 water quality
conditions throughout this shallow embayment.
This station may not be truly representative of
water quality in shoal areas because the shoreline
is highly dissected by smaller tidal tributaries. In
Table 24. Hectares of SAV by density category and percentage of Tier I SAV addltlon' mOSt Or a11 °f the SAV beds m thlS Seg'
restoration goal (2,474 hectares) and Tier III SAV restoration target (8,815 ment are monospecific and are composed of R.
hectares) are listed for 1 970-1 991 for CBP Segment EE1 (Eastern Bay).
Sources: Anderson and Macomber, 1 980; Batiuk et al., 1 992; Orth et al., 1 985
1986, 1987, 1989, 1991 , and 1992; Orth and Nowak, 1990.
100^ '
•o 90"
3 8°-
S> 70-
M 6°-
0 50-
S 40- 0f\ J
CA 1 f
c 30- mm\
tt 1 l^r 1
o 20- f\ ~f\
4) 1 ^^^^1 _^___H
10 I, IllrrfliflJ'
r
LJ
maritima. Fluctuations in abundance may occur
j
naturally due to the biology of this species regard-
less of water quality.
Achievement of the Tier I restoration goal
and the Tier III restoration target was highest in
1978 (58 percent and 16 percent, respectively) and
lowest in 1991 (3 percent and <1 percent, respec-
tively) (Table 24).
71 72 73 74 75 76 77 78 79 ^80 SI '82 TO -84 re W B7
Year (no bar = ground survey data not available)
TO 30
Figure 63. Percentage of Maryland Department of Natural Resources SAV
Ground Survey Program stations sampled where SAV was observed for CBP
Segment EE1 (Eastern Bay). Ground survey data were not available for 1988.
Source: Chesapeake Bay Program, unpublished data c.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
83
-------
Ch ipter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Middle Central
Chesapeake Bay
The Middle Central Chesapeake Bay segment
covers a broad arez. of the middle mainstem Bay,
from the Chesapeake Bay Bridge south to Cove
Point (Just north of the Patuxent River mouth).
Over the last two de :ades, no more than 77 hectares
of SAV have been reported by the aerial survey,
with only 12 hectares or less reported annually
since 1986 (Figure 64, Table 25).
The Maryland Department of Natural Re-
sources ground survey also reported very little
SAV (0-2 percent of the stations vegetated) in this
segment since 1971 (Figure 66). The 1990 U.S.
Fi>h and Wildlife Ssrvice clam survey found SAV
at only 2.2 percent of 45 sites visited, primarily in
Herring Bay (Jorde et al., 1991). Ruppia maritima
was the only species reported.
The shoreline of this segment is quite ex-
posed. Because of high wave and current energy,
much shoal habitat is unsuitable for SAV growth.
A considerable amount of bottom habitat under two
meters in depth remains, however, along the shore-
lines of Kent Island and below the Little Choptank
River and at the mouths of Eastern Bay and the
Cr optank River that could potentially support SAV.
Some ground surveys reported SAV in small
tidally-influenced ponds and creeks along this
segment's shorelines (e.g., along the western shore
of Kent Island). Species reported from this seg-
ment were C. demersum, Z. palustris, P. pectinatus,
M. spicatum, P. perfoliatus, and R. maritima.
Water quality in this mainstem Bay segment
met all five SAV habitat requirements from 1984
to 1988 and in 199:; four of the five SAV habitat
requirements were met in 1989 and 1990 (Figure
65). In 1978, achievement of the Tier I restoration
goal and the Tier III restoration target was 75
i* ^
isrv^f -
^,V«.f v^-'
\^f >£""
^W^-f^'
' f^ V^"
'^ r^-
x
M% *.
x. ^
percent and 2 percent, respectively, which declined
to 2 percent and <1 percent, respectively, by 1991
(Table 25). Excessive wave energy and currents
and the lack of a sufficient local source of
propagules— rather than unsuitable water quality
conditions—may be preventing SAV from gaining
a foothold in most of the potential habitats de-
scribed above.
84
Trends in the Distribution, Abundance, and Habitat Quality of
Sibmerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Middle Central Chesapeake Bay
to
£
CO
100-
90-
80-
70-
60-
50-
40-
30-
20-
10-
0-
ND ND ND ND ND ND NO ND
ND ND ND ND
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90
ND = NoData ^ 70-100% Q 40-70% Q 10-40% • <10% | No Density Reported
Figure 64. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment CB4 (Middle Central
Chesapeake Bay), the Tier I SAV restoration goal is 103 hectares.
Sources: Anderson and Macomber, 1980; Batiuk, 1992; Orth et al., 1985, 1986, 1987, 1989, 1991, and 1992; Orth and Nowak, 1990.
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = No Data
D Kd
DIP
DIN
CHLA
TSS
Figure 65. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment CB4 (Middle Central
Chesapeake Bay). No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters were
not available to calculate growing season medians: Kd (1970,1971,1981-1983); TSS (1971-1973,1981-1983); CHLA (1970-1972,1981-1983);
DIP (1971,1972,1981 -1983); and DIN (1971,1972,1981 -1983). Numbers of SAV habitat requirements with growing season medians are shown
above bars when some values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Yea
Middle Central Chesapeake Bay
r Hectares of SAV liy —,
Density Category % of Tier I % of Tier HI
' Segment Restoration Restoration
<10% 1(MO% 40-70". 70-100% Total Goal Goal
70
71
72
73
74
75
76
77
78
79
•80
•81
32
•83
•84
•85
•86
•87
•88
89
•90
•91
-
-
•
-
-
-
- •
•
0
3
0
0
-
0
0
0
-
-•
-
-
-
-
-
•
0
5
2
0
-
2
0
<1
-
-
-
•
-
-
-
•
5 12
2' 25
< 9
5 2
-
< 0
5 0
2 0
-
-
77
-
-
-
-
-
17
54
12
7
•
3
5
2
-
•
75%
•
•
-
-
-
17%
52%
12%
7%
-
3%
5%
2%
-
-
2%
-
-
-
-
•
<1%
1%
<1%
<1%
-
<1 /o
<1%
<1%
Tatte 25. Hectares of SAV by density category and percentage of Tier I SAV
restoration goal (103 hectares) and Tier III SAV restoration target (3,496
hectares) are listed for 1970 to 1991 for CBP Segment CB4 (Middle Central
Chesapeake Bay).
Soirees: Anderson and Macoinber, 1980; Batiuketal., 1992;0rthetal., 1985,
1986,1987,1989,1991, and '992; Orth and Nowak, 1990.
100-
0)70-
O 50-
S 40-
(A
c x'
§20-
S.
10-
'^•^^^•^'^'^•^^•^'•^•^•^•^•^•^•^•^~~''
71 72 73 74 75 76 77 78 79 M 31 B2 B3 34 "85 36 S7 -B8 B9 SO 91
Year (no b ir = ground survey data not available)
Figure 66. Percentage of Maryland Department of Natural Resources SAV
Ground Survey Program stations sampled where SAV was observed for CBP
Segment CB4 (Middle Central Chesapeake Bay).
Source: Chesapeake Bay Program, unpublished data c.
86 Trends in the Distribution, Abundance, and Habitat Quality of
S jbmerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Choptank River
The Choptank River region includes the
Choptank and Little Choptank rivers, the many
small creeks and rivers entering the Choptank River
(e.g., Harris and Broad creeks and the Tred Avon
River), and the broad lower Choptank River ex-
tending from the mainstem Bay to Cambridge,
Maryland. Extensive documentation exists on the
recent history of SAV distribution in the Choptank
River because of its proximity to the University of
Maryland Horn Point Environmental Laboratory
and the regular monitoring of many SAV beds in
this river (Stevenson et al., 1993).
The greatest distribution of SAV reported
through the aerial survey program was in 1978
when 1,999 hectares were reported in the lower
Choptank and Little Choptank rivers (Figure 67,
Table 26), and 100 hectares were mapped in the
Choptank River (Figure 69, Table 27). By 1984,
SAV had declined dramatically; only 86 hectares
were mapped in the lower Choptank and Little
Choptank rivers while no SAV was recorded in the
Choptank River. In the lower Choptank and Little
Choptank rivers, SAV distribution increased sub-
stantially by 1985 (1,778 hectares), but has fluctuated
widely from 1985 through 1991. In 1991, 112
hectares were reported. Submerged aquatic veg-
etation has consistently been present in several
areas, notably Blackwalnut and Cook Point coves
at the mouth of the Choptank River, Chapel Creek,
the mouth of both Harris and Broad creeks, and
Brannock Bay. Although SAV was abundant in the
Little Choptank River in the early 1980s, very little
SAV has been mapped in recent years. Small beds
of SAV were mapped in the Choptank River (36
hectares in 1985 and 10 hectares in 1986), however,
no SAV has been mapped upriver from the Route
50 Choptank River bridge at Cambridge, Maryland
since 1986.
The Maryland Department of Natural Re-
sources ground survey reported abundant SAV in
the lower Choptank and Little Choptank rivers in
the 1970s, with the percentage of vegetated stations
declining and remaining low from the early to mid-
1980s (Figure 71). The percentage of vegetated
stations increased in the late 1980s, with the highest
number reported in 1988 (45 percent), declining to
only 4 percent by 1991. Very few of the stations
in the Choptank River had SAV in the 1970s; after
1980, SAV was not found at any of the stations
(Figure 72). The survey documented Z. marina in
the lower portions of the Choptank and Little
Choptank rivers in the 1970s, but this species has
not been found since the late 1970s by any survey
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
87
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
2000
1600-
1200-
o
M
s>
S3 soon
400-
0
Lower Choptank River
ND ND ND ND ND ND ND
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 "90
ND = No Data [H 70-100% D 40-70% 0 10-40% • <10%
No Density Reported
Figure 67. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment EE2 (Lower Choptank
River), the Tier I SAV restortation target is 3,646 hectares.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al, 1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
I 5-
o>
I
cr
5
en
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData [J Kd Q DIP 0 DIN • CHLA • TSS
Figure 68. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment EE2 (Lower Choptank
River). No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters were not available
to calculate growing season medians: Kd (1970-1974,1977-1979,1981 -1983); TSS (1972,1973,1977-1979,1981 -1983); CHLA (1970,1971,1973,
1977-1979,1981-1983); DIP (1970,1971,1973,1977-1983); and DIN (1970,1971,1973,1977-1983). Numbers of SAV habitat requirements with
growing season medians are shown above bars when some values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
88
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
of this region. Ruppia maritima was the only spe-
cies reported by the survey in recent years. The
overall pattern of change in SAV recorded through
the ground survey is similar to that documented
through the aerial survey (Figures 67 and 69).
The 1990 U.S. Fish and Wildlife Service clam
survey found SAV at only 4.3 percent of the 508
sites visited (Jordeet al., 1991). The sites with SAV
were primarily those closest to the Choptank River
mouth. Zannichellia palustris was the only species
reported.
Ruppia maritima was the dominant species
reported by ground surveys associated with the
aerial survey program throughout both the Choptank
and Little Choptank rivers. Zannichellia palustris
and P. pectinatus were the only other species re-
ported from these segments. University of Maryland
Horn Point Environmental Laboratory scientists
had limited success in transplanting R. maritima
and P. pectinatus between 1984 and 1987 (Steven-
son et al., 1993). Virginia Institute of Marine
Science and Horn Point Environmental Laboratory
scientists planted Z. marina seeds off Tilghman
Island in 1988 and again in 1989, as well as at the
mouth of Irish Creek and Brannock Bay in 1989.
Although seeds germinated and showed some
springtime growth in both years, the plants did not
survive a full year (Orth, unpublished data).
Water quality in the lower Choptank and
Little Choptank rivers met all five SAV habitat
requirements from 1985 to 1988 and in 1991, with
four of the five SAV habitat requirements met in
1988 and 1989 (Figure 68). Data from a single
station in the middle of the lower Choptank River,
combined with data from one station in the middle
of the Little Choptank River, were used to charac-
terize water quality conditions from 1984 to 1991
for this segment. As in Eastern Bay, the rapid
fluctuation of SAV in this segment, even though
the water quality appeared suitable based on the
SAV habitat requirements, remains problematic.
Lower Choptank River
r Hectares of SAV by—i
Density Category % of Tier I %ofTwl
1 Segment Restoration Restoration
Year <10% 10-40% 40-70% 70-100% Total Goal Goal
70
71
72
73
74
75
76
77
78
79
•80
•81
'82
•83
B4
'85
'86
•87
IOQ
OO
•89
•90
•91
-
-
11
88
39
40
18
2
1
-
-
26
497
140
79
208
52
78
-
-
32
900
179
125
552
101
33
-,
-
17
293
101
109
89
33
0
1,999
-
86
1,778
459
353
867
188
112
55%
-
2%
49%
13%
10%
24%
5%
3%
17%
-
<1%
15%
4%
3%
7%
2%
1%
Table 26. Hectares of SAV by density category and percentage of Tier I SAV
restoration goal (3,646 hectares) and Tier III SAV restoration target (11,648
hectares) are listed for 1970 to 1991 for CBP Segment EE2 (Lower Choptank
River).
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al., 1985,
1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
Again, data from the two mid-embayment stations
may not be fully representative of water quality in
the shoal areas where the shoreline is highly dis-
sected by smaller tidal tributaries. In addition, most
if not all SAV beds in this segment are monospe-
cific (R. maritima) and fluctuations in abundance
may occur regardless of water quality. In the ad-
jacent segment, for the remaining upriver portion
of the Choptank River, water quality conditions
rarely met two of the five SAV habitat require-
ments (Figure 70).
Achievement of the Tier I restoration goal
and the Tier III restoration target in the lower
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Choptank River
>
CO
"o
0>
CO
1
100-
90-
80-
70-
-
60-
50-
40-
30-
20-
10-
n —
ND ND ND ND ND ND ND
ND ND ND ND
ND 0
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 91
[F] 70-100% Q 40-70% 0 10-40% | <10% H No Density Reported
ND = No Data 0 = Area surveyed, no SAV mapped
Figure 69. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment ET5 (Choptank River),
the Tier I SAV restoration goal is 191 hectares.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al,. 1985,1986,1987, 1989,1991, and 1992; Orth and Nowak, 1990.
5-
4-
s 3-
2-
CO
"5
(4)
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData Q Kd Q D,p ^ D|N | CHLA • TSS
Figure 70. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment ET5 (Choptank River).
No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters were not available to calculate
growing season medians: Kd (1970-1975,1977-1979,1981-1983); TSS (1973,1981-1983); CHLA (1970,1971,1973,1981-1983); DIN (1970-73,
1981-1983); and DIP (1970,1971,1973,1981-1983).
Sources: Chesapeake Bay Program, 1993a and 1993b.
90
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Year <
70
71
72
73
74
75
76
77
78
79
to
•81
•82
•83
W
•85
B6
•87
•88
'89
90
91
• Hectares
Density (
10% 10-40%
0 0
<1 1
0 4
0 0
0 0
0 0
0 0
Choptank
afSAVby — •
iategory
40-70% 70-100%
0
8
4
0
0
0
0
0
26
2
0
0
0
0
River
Segment
Toti
100
0
36
10
0
0
0
0
% of Tier I
Restoration
Goal
52%
0%
19%
5%
0%
0%
0%
0%
% of Tier III
Restoration
Goal
3%
0%
1%
<1%
0%
0%
0%
0%
Percent Stations Vegetated
,3886883888
Figure?
Ground.
Segmen
available
Source:
100- '
|".
S 80-
g> 70-
« 6°-
Jso-
S 40-
V>
£ 30-
I20-
0. 10-
/
. ^j
W\ I
I kprfT^i 1
fm 1 111 fl 1 1*^
< JJiJJJJJiflCltiJJcin/ JtU
71 72 73 74 75 76 77 78 79 TO 31 '82'83'84'85186'87188'899091
Year (no bar = ground survey data not available)
1. Percentage of Maryland Department of Natural Resources SAV
Survey Program stations sampled where SAV was observed for CBP
t EE2 (Lower Choptank River). Ground survey data were not
sfor 1971 and 1972.
Chesapeake Bay Program, unpublished data c.
f\ * l\
A if* A
*/*mjmmJm.m/^*^^^^ ZZZlP
71 72 73 74 75 76 77 78 79 tt) B1 K S3 84 B5 B6 «7 B8 39 90 91
Table 27. Hectares of SAV by density category and percentage of Tier I (191
hectares) SAV restoration goal and Tier III (3,009 hectares) SAV restoration
target are listed for 1970 to 1991 for CBP Segment ET5 (Choptank River).
Sources: Anderson and Macomber, 1980; Batiuketal., 1992; Orthetal., 1985,
1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
Choptank and Little Choptank rivers was highest
in 1978 (55 percent and 15 percent, respectively)
and lowest in 1984 (2 percent and <1 percent,
respectively) (Table 26). The absence of SAV in
the Choptank River, as documented through the
aerial survey, has resulted in 0 percent achievement
of both the Tier I goal and the Tier III target since
1987 (Table 27).
Figure 72. Percentage of Maryland Department of Natural Resources SAV
Ground Survey Program stations sampled where SAV was observed for CBP
SegmentET5(ChoptankRiver).Groundsurveydatawerenotavailablefor1971,
1972, and 1987.
Source: Chesapeake Bay Program, unpublished data c.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
91
-------
Chapter 4: Regional Trends in SAV Distribution, Abundsr.ce, and Habitat Quality
Patuxent River
Over the last 1 wo decades, the Patuxent River
has had very limited stands of SAV—documented
through the baywide aerial survey and the Mary-
land Department of Natural Resources ground survey.
This situation contrasts with earlier years when
ground surveys reported beds of SAV in many
sections of the rivsr and historical aerial photo-
graphs showed dense stands of SAV in the lower
Patuxent River. Zostera marina was reported around
Solomons Island in the late 1940s (Elser, 1969) and
prior to 1971 (Boynton, personal communication).
Oi:her species noted during these years by Stewart
(1962), Anderson (1969), and Bayleyetal. (1978)
were Z. palustris, F. canadensis, P. perfoliatus, P.
pectinatus, N. flexilis, and R. maritima.
The baywide aerial survey has reported no
more than 55 hectares of SAV in any one year
throughout the river (Figures 73,75, and 77; Tables
28,29, and 30). Submerged aquatic vegetation was
concentrated in the lower Patuxent River around
Broomes Island in the middle to late 1980s.
The Maryland Department of Natural Re-
sources ground survey reported almost no SAV at
50 stations sampled in the lower and middle Patux-
ent River and no SAV in the upper Patuxent River
between 1971 and 1989 (Figures 79 and 80). These
findings confirm the results of the aerial survey,
although drift SAV was commonly observed and
recorded.
. Ruppia maritima, M. spicatum, Z. palustris,
and P. pectinatus were the species reported most
frequently by ground surveys in the lower and
m iddle sections of the river. The Maryland Capital
Pzxks and Planning Commission and other surveys
found numerous species in the upper reaches of the
river (above Deep Landing, but primarily above
Jug Bay) including V. americana,N. guadalupensis,
E. canadensis,N. minor,N. gracillima, C. demersum,
Z. palustris, P. perfoliatus, P. pectinatus, P. crispus,
JO
V
and P. pusillus. Many of these species were ob-
served in numerous small tidal creeks entering the
mainstem Patuxent River and cannot be mapped
using 1:24,000 scale aerial photography.
In the lower Patuxent River, all SAV habitat
requirements were met in 1985, 1990, and 1991
with three to four SAV habitat requirements achieved
during the remaining four years since 1985 (Figure
74). Water quality conditions in the middle and
upper Patuxent River seldom met more than one
SAV habitat requirement (Figures 76 and 78).
92 Trends in the Distribution, Abundance, and Habitat Quality of
S jbmerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Lower Patuxent River
3
CO
"5
(A
1
W"*
100-
90-
80-
70-
"
60-
50-
30-
20-
10-
o-
/i •"• '
J\ ,
/• /
ND ND ND ND ND pjj ] / ', ND Q| 0 0
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 "90 91
ED 70-100% D 40-70% E2 10-40% • <10% • No Density Reported
ND = No Data 0 = Area surveyed, no SAV mapped
Figure 73. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment LE1 (Lower Patuxent
River), the Tier I SAV restoration goal is 132 hectares.
Sources: Anderson and Macomber, 1980; Batiuk et al, 1992; Orth et al., 1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86
ND = NoData Q Kd Q D|P £j D|N fl CHLA
87 '88 '89
I TSS
'90 '91
Figure 74. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment LE1 (Lower Patuxent
River). No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters were not available
to calculate growing season medians: Kd (1970-1976,1979,1981-1984); TSS (1973,1976,1979,1981-1984); CHLA (1971-1973,1976,1979,
1981-1984); DIP (1976,1979,1981-1984); and DIN (1972,1973,1976,1979,1981-1984). Numbers of SAV habitat requirements with growing
season medians are shown above bars when some values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
93
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Middle Patuxent River
>
CO
"o
to
0)
fi
0>
100-
90-
80-
70-
60-
50-
40-
30-
20-
10-
n-
ND ND ND ND ND ND ND ND ^ ND ND ND ND ND 0 0 1 ^ ND 0 0 0
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 "91
M 70-100% D 40-70% 0 10-40% • <10% • No Density Reported
ND = No Data 0 = Area surveyed, no SAV mapped
Figure 75. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment RET1 (Middle Patuxent
River), the Tier I SAV restoration goal is 16 hectares.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al., 1985,1986,1987, 1989, 1991, and 1992; Orth and Nowak, 1990.
4-
CO
•5
I
2-
1-
(*)
(3)
0 NO
0)
0
ND ND ND ND
ND
ND ND ND ND
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData Q Kd Q Djp £j D|N | CHLA • TSS
Figure 76. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment RET1 (Middle Patuxent
River). No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters were not available
tocafculate growing season medians: Kd (1971 -1976,1979,1981 -1984); TSS (1970-1977,1979,1981 -1984); CHLA (1971 -1976,1979,1981 -1984);
DIP (1971,1973-1976,1979,1981-1984); and DIN (1970-1976,1979,1981-1984). Numbers of SAV habitat requirements with growing season
medians are shown above bars when some values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
94
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Upper Patuxent River
CO
*o
is
I
100-
90-
80-
70-
60-
50-
40-
30-
20-
10-
ND ND ND ND ND ND ND ND ND ND ND ND ND 0 0 0 ND 0 0 0
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ED 70-100%
D 40-70% [2 10-40% • <10% • No Density Reported
ND = No Data 0 = Area surveyed, no SAV mapped
Figure 77. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment TF1 (Upper Patuxent
River), the Tier I SAV restoration goal is six hectares.
Sources: Anderson and Macomber, 1980; Batiuk et al, 1992; Orth et al., 1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
4-
I »_,
3 3-
I
cc
73
I 2H
en
(2) (2)
ND NO
ND ND ND ND
IIIUL
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData D Kd Q DIP • CHLA • TSS
Figure 78. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment TF1 (Upper Patuxent
River). No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters were not available
to calculate growing season medians: Kd (1971-1976,1979,1981-1984); TSS (1973,1981-1984); CHLA (1971-1973,1981-1984); and DIP (1973,
1981-1984). Numbers of SAV habitat requirements with growing season medians are shown above bars when some values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
95
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Lower Patuxent River
Middle Patuxent River
r Hectares of SAV by — • , Hectares of SAV by — ,
Density Category %ofTwl %ofTierlll Density Category %ofTierl %ofTierlll
Segment Restoration Restoration Segment Restoration Restoration
Year <10% 10-40% 40-70% 70-100% Total Goal Goal Year <10% 1(MO% 40-70% 70-100% Total Goal Goal
70
71
72
73
74
75
76
77
78 26 20% <1%
79
•80
•81
•82
•83
B4 0 1 4 9 14 11% <1%
•85 10 43 1 <1 55 42% 2%
•86 <1 6 <1 1 9 7% <1%
•87 0 20 17 2 39 30% 1%
•88
•89 0 <1 3 0 4 3% <1%
•90 0 0 0 0 0 0% 0%
•91 0 0 0 0 0 0% 0%
70
71
72
73
74
75
76
77
78
79
'80
•81
82
'83
'84
'85
'86
'87
'88
'89
»
91
.
.
.
.
.
.
.
.
.
.
.
.
.
.
000
000
<1 7 2
0 3 <1
.
000
000
000
. .
-
.
.
.
.
-
.
4 25% <1%
.
-
.
.
.
0 0 0% 0%
0 0 0% 0%
0 10 63% 1%
<1 5 31% <1%
.
0 0 0% 0%
0 0 0% 0%
0 0 0% 0%
Table 28. Hectares of SAV by density category and percentage of Tier I SAV Table 29. Hectares of SAV by density category and percentage of Tier I SAV
restoration goal (132 hectares) and Tier III SAV restoration target (2,653 restoration goal (16 hectares) and Tier III SAV restoration target (959 hectares)
hectares) are listed for 1970 to 1991 for CBP Segment LE1 (Lower Patuxent are listed for 1970 to 1991 for CBP Segment RET1 (Middle Patuxent River).
River). Sources: Anderson and Macomber, 1 980; Batiuk et al., 1 992; Orth et al., 1 985,
Sources: Anderson and Macomber 1980; Batiuk etal., 1992; Orth et al., 1985, 1986, 1987, 1989, 1991, and 1992; Orth and Nowak, 1990.
1 986, 1 987, 1 989, 1 991 , and 1 992; Orth and Nowak, 1 990.
100 -/
•g 90-
o 80-
0) 70-
> m
a 6°-
b 50-
5 <°-
- 30-
I20-
71 72 73 74 75 76 77 78 79 BO B1 32 S3 W W B6 B7 88 «9 '90 91
Year (no bar = ground survey data not available)
Percent Stations Vegetated
00&38SS83S88
jm
717273747576777879'80181'82'8384'85186'87'88B9'90'91
Year (no bar - ground survey data not available)
Figure 79. Percentage of Maryland Department of Natural Resources SAV Rgure 80. Percentage of Maryland Department of Natural Resources SAV
Ground Survey Program stations sampled where SAV was observed for CBP Ground Survey Program stations sampled where SAV was observed for CBP
Segment LE1 (Lower Patuxent River). Ground survey data were not available SegmentRETl (Middle Patuxent River). Ground survey data were not available
for 1971 and 1989. for 1984, 1985, 1986, 1989, and 1990.
Source: Chesapeake Bay Program, unpublished data c.
Source: Chesapeake Bay Program, unpublished data c.
96
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Upper Patuxent River
Because of the recent scarcity of SAV in this
%ofTierl %olTierin river, achievement of the Tier I restoration goal and
'ier III restoration target has been minimal
the late 1980s (Tables 28, 29, and
Year
70
71
72
73
74
75
76
77
78
79
•80
•81
'82
•84
"85
'86
•87
IQQ
00
•89
•90
•91
r
-
-
0
0
0
0
0
0
0
Hectares of SAV by — i
Density Category % of Tier I % of Tier III
Segment Restoration Restoration
1040% 40-70% 70-100% Total Goal Goal
-
-
0
1
0
0
0
0
0
-
-
0
0
0
0
0
0
0
-
-
0
5
0
0
0
0
0
<'.
-
0
6
0
0
0
0
0
17%
-
0%
100%
. 0%
0%
0%
0%
0%
<;%
•
0%
<1%
0%
0%
0%
0%
0%
Table 30. Hectares of SAV by density category and percentage of Tier I SAV
restoration goal (6 hectares) and Tier III SAV restoration target (890 hectares)
are listed for 1970 to 1991 for CBP Segment TF1 (Upper Patuxent River).
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al., 1985,
1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
Trends in the Distribution, Abundance, and Habitat Quality of • 97
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries; 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Nanticoke, Wicomico,
Manokin, Big Annemessex,
and Pocomoke Rivers
This region includes the five tributaries en-
tering Chesapeake Bay along the middle Eastern
Shore (the Nanticoke, Wicomico, Manokin, Big
Annemessex, and Pocomoke rivers). No SAV has
been reported from the Nanticoke, Wicomico, and
Pocomoke rivers since the first baywide aerial
survey in 1978 (Figures 81, 83, and 89; Tables 31,
32, and 35). Submerged aquatic vegetation has
bsen consistently leported from both the Manokin
('^3-143 hectares) and Big Annemessex (96-197
hectares) rivers (Figures 85 and 87; Tables 33 and
34). The SAV beds were restricted primarily to
areas close to the river mouths and in small coves
or protected areas.
The Maryland Department of Natural Re-
sources ground survey found no SAV in the Nanticoke
and Wicomico ri vors since the first survey in 1971.
A much greater percentage of vegetated stations
was found in both the Manokin and Big Annemessex
r.vers in the 1970s and late 1980s compared to the
period from 1978 through 1983 (Figures 91 and
92). No ground survey stations were located on the
F'ocomoke River. The patterns of SAV distribution
in these tributaries during the 1980s parallel those
reported by the aerial surveys.
Four species have been reported from these
tributaries in past years. Zostera marina and R.
riaritima were the most commonly reported spe-
c ies with P. pectinatus and P. perfoliatus occasionally
found in samples. Ruppia maritima and P. perfoliatus
were found from tie late 1960s through 1971 in the
Nanticoke arid Wicomico rivers but no SAV has
been reported since 1971. Zostera marina and R.
riaritima were reported in the Manokin and Big
Annemessex riveis during the 1960s. In the 1970s,
however, both species declined—especially Z. ma-
nna. Consequently, the Maryland Department of
' s J f J—'
% t~*J fj
\^ - o •*ff
•t?
.(^
•ti
v^**
'-»
Natural Resources ground survey reported R.
maritima more frequently in the 1970s and 1980s.
Although the ground surveys associated with the
baywide aerial survey reported only R. maritima
in the Manokin River, the Maryland Department of
Natural Resources ground survey reported Z. marina
at two locations. Both species have been reported
in the Big Annemessex River with R. maritima
reported most frequently.
Water quality in the Nanticoke, Wicomico,
and Pocomoke rivers has been unsuitable for SAV
survival from 1970 to 1991 (Figures 82, 84, and
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Nanticoke River
>
J2
o
en
2
TO
1
100-
90-
80-
70-
60-
50-
40-
30-
20-
10-
,
,
ND ND ND ND ND ND ND ND 0 ND ND ND ND ND 0 0 0 0 ND 0 0 0
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 91
EH 70-100% D 40-70% H 10-40% • <10% • No Density Reported
ND = No Data 0 = Area surveyed, no SAV mapped
Figure 81. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment ET6 (Nanticoke River),
there is no Tier I SAV restoration goal.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al., 1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
5-
4-
cr
o>
or
« 3-
(") (4)
0 0 ND ND ND ND ND ND ND
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData D Kd Q DIP 0 DIN • CHLA • TSS
Figure 82. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment ET6 (Nanticoke River).
No SAV habitat requirements met=0; no water quality data available=ND. Sufficient data for the following parameters were not available to calculate
growing season medians: Kd (1970-1975,1977-1985); TSS (1972,1979-1985); CHLA (1970-1972,1979-1985); DIP (1970,1972,1979-1985); and
DIN (1972,1979-1985). Numbers of SAV habitat requirements with growing season medians are shown above bars when some values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Nanticoke River
Yer
70
71
72
73
74
75
7€
77
78
79
K
B1
•82
•83
•84
•85
•86
•87
•88
•89
•90
•91
r
<10%
.
-
-
-
-
-
-
-
-
-
-
-
-
0
0
0
0
-
0
0
0
Hectares of SA/by
Density Category
1
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Wicomico River
>
CO
"o
8
§
I
100-
90-
80-
70-
•
60-
50-
40-
30-
20-
10 -
ND ND ND ND ND ND ND ND 0 ND ND ND ND ND 0 0 0 0 ND 0 0 0
Q_L r
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 91
E3 70-100% D 40-70% 0 10-40% • <10% • No Density Reported
ND = No Data 0 * Area surveyed, no SAV mapped
Figure 83. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment ET7 (Wicomico River),
there is no Tier I SAV restoration goal.
Sources: Anderson and Macomber, 1980; Batjuk et al., 1992; Orth et al,. 1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
5-
B
1 3H
2-
1-
0
(4)
(2) (3)
0 0 ND ND
(3)
0
I (
(4) (4) (4)
0 0 0 ND ND ND ND ND ND
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData Q Kd Q DIP 0 DIN • CHLA • TSS
Figure 84. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment ET7 (Wicomico River).
No SAV habitat requirements met=0; no water quality data available = ND. Sufficient data for the following parameters were not available to calculate
growing season medians: Kd (1970-1985); TSS (1972,1973,1979-1985); CHLA (1970-1973,1979-1985); DIP (1970,1972,1973,1979-1985);
and DIN (1972,1973,1979-1985). Numbers of SAV habitat requirements with growing season medians are shown above bars when some values
were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
101
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Manokin River
250 -f
200-1
to
1001
50 H
ND ND ND ND ND ND ND
ND ND ND ND 0
91
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89
£3 70-100% Q 40-70% £2 10-40% | <10% H No Density Reported
ND = No Data 0 - Area surveyed, no SAV mapped
Figure 85. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment ET8 (Manokin River),
the Tier I SAV restoration goal is 272 hectares.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al., 1985, 1986, 1987, 1989, 1991, and 1992; Orth and Nowak, 1990.
NO ND ND ND ND ND ND ND ND
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = No Data
Kd
D DIP
DIN
CHLA
TSS
Rgure 86. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment ET8 (Manokin River).
No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters were not available to calculate
growing season medians: Kd (1970-1975,1977-1985); TSS (1970-1973,1976-1985); CHLA (1970-1973,1977-1985); DIP (1970-1973,1977-1985);
and DIN (1970-1973,1977-1985). Numbers of SAV habitat requirements with growing season medians are shown above bars when some values
were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
102
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
r
Year <10%
70
71
72
73
74
75
76
77
78
79
80
81
82
83
'84 0
'85 <1
'86 5
87 4
88
89 1
•90 4
"91 4
Manokin River
Hectares of SAV by — .
Density Category % of Tier 1 % of Tier 111
' Segment Restoration Restoration
10-40% 40-70% 70-100% Total Goal Goal
-
-
-
-.
-
-
-
.
-
-
-
-
-
0
22
54
29
.
10
18
23
-
-
-
-
-
-
-
-
-
-
-
•
0
48
57
95
.
65
81
69
•
-
-
.
-
-
-
-
-
-
-
-
-
0
2
27
11
-
12
0
19
-
-
-
-
-
-
-
83
-
-
-
-
-
0
73
143
139
-
88
.103
115
-
-
-
-
-
-
-
30%
-
-
-
-
-
0%
27%
52%
51%
.
32%
38%
42%
-
-
-
-
-
-
-
2%
-
-
-
-
-
0%
2%
4%
4%
-
2%
3%
3%
Year
70
71
72
73
74
75
76
77
78
79
80
81
82
83
'84
'85
86
87
88
89
"90
91
r
-
-
-
-
•
-
-
-
-
-
-
-
-
0
3
6
0
-
4
10
0
Big Annemessex River
Hectares of SAV by — i
Density Category % of Tier I % of Tier II
' Segment Restoration Restoration
10-40% 40-70% 70-100% Total Goal Goal
-
-
-
-
-
-
-
-
-
-
•
-
•
0
21
52
19
-
23
21
61
:
•
•
•
•
-
-
-
-
-
•
-
-
0
100
86
75
-
23
45
53
:
-
-
-
-
-
-
-
-
-
-
-
-
0
29
25
2
-
95
53
63
:
-
•
-
-
-
-
197
-
-
-
-
-
0
153
169
96
-
145
129
177
.
-
•
-
•
-
-
54%
-
•
-
-
-
0%
42%
46%
26%
•
40%
35%
48%
-
. -
•
-
-
-
-
10%
-
. -
-
-
-
0%
8%
8%
5%
-
7%
6%
9%
Table 33. Hectares of SAV by density category and percentage of Tier I SAV
restoration goal (271 hectares) and Tier III SAV restoration target (3,763
hectares) are listed for 1970 to 1991 for CBP Segment ET8 (Manokin River).
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al, 1985,
1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
Table 34. Hectares of SAV by density category and percentage of Tier I SAV
restoratJongoal(363hectares)andTierlllSAVrestoratJon target (2,044hectares)
are listed for 1970 to 1991 for CBP Segment ET9 (Big Annemessex River).
Sources: Anderson and Macomber, 1980; Batiuk etal., 1992; Orthetal., 1985,
1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
103
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Big Annemessex River
250 -f
200-
150,
O
50-
ND ND ND ND ND ND ND
ND ND ND ND 0
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 "90 '91
£3 70-100% Q 40-70% 0 10-40% fj <10% |J No Density Reported
NO = No Data 0 = Area surveyed, no SAV mapped
Figure 87. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment ET9 (Big Annemessex
River), the Tier I SAV restoration goal is 363 hectares
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al. 1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
5H
4H
"
I
2-
1-
0
NO ND ND ND ND ND
ND ND ND ND ND ND ND
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData Q Kd D DIP 0 DIN • CHLA • TSS
Figure 88. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment ET9 (Big Annemessex
River). No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters were not available
to calculate growing season medians: Kd (1970-1975,1977-1985); TSS (1970-1976,1978-1985); CHLA (1970-1975,1978-1985); DIP (1970-1975,
1978-1985); and DIN (1970-1975,1978-1985). Numbers of SAV habitat requirements with growing season medians are shown above bars when
some values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
104
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Pocomoke River
3
CO
"o
CO
s
.2
CD
100-
90-
80-
70-
60-
50-
40-
30-
20-
10-
r\ —
.
ND ND ND ND ND ND ND ND 0 ND ND ND ND ND 0 0 0 0 ND 0 0 0
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 "90
[S3 70-100%
n 40-70% 0 10-40% • <10% • No Density Reported
ND = No Data 0 = Area surveyed, no SAV mapped
Figure 89. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment ET1 0 (Pocomoke River),
there is no Tier I SAV restoration goal.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al., 1985, 1986, 1987, 1989, 1991, and 1992; Orth and Nowak, 1990.
c
S
'5
O1
•
1
XJ
re
1
4H
2H
H
o
(*)
(3) «)
ND 0 ND ND 0
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData [~] Kd Q DIP 0 DIN • CHLA • TSS
Figure 90. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment ET10 (Pocomoke
River). No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters were not available
to calculate growing season medians: Kd (1970-1975,1977-1985); TSS (1970,1972,1973,1981 -1985); CHLA (1970-1973,1980-1985); DIP (1970-
1973,1981 -1985); and DIN (1970,1972,1973,1981 -1985). Numbers of SAV habitat requirements with growing season medians are shown above
bars when some values were missing.
Sources; Chesapeake Bay Program, 1993a and 1993b.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
105
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Pocomoke River 10° '
r Hectares of SAV by — i "8 90"
Density Category %ofTierl % of Tier! g ao-
Segment Restoration Restoration §> 70-
Year <10% 10-40% 40-70% 70-100% Total Goal Goal > m
70 0 50-
71 | «•
72 | 3°-
74 .. . . . . 0. 10-
0- t
75 .... ^
76
77 Rgure !
78 - - 0-0% Ground
_, Segmen
1972,ar
190 Source:
81
•32 100-
83 - - - - - - * 90"
'84 0 0 0 0 0 0%
'85 0 0 0 0 0 0% 1* 7°'
86 0 0 0 0 0 0% c 5
87 0 0 0 0 0 0% | 40.
"88 £ 30-
89 0 0 0 0 0 0% I 20-
"90 0 0 0 0 0 0% 5 10-
sty
772*B/l/arl/l/l/
r
/
\w
1 72 73 74 75 76 77 78 79 '80 81 B2 83 84 BS 06 B7 '88 89 90 91
Year (no bar = ground survey data not available)
H. Percentage of Maryland Department of Natural Resources SAV
Survey Program stations sampled where SAV was observed for CBP
t ET8 (Manokin River). Ground survey data were not ava lable for 1 971 ,
id 1988.
Chesapeake Bay Program, unpublished data c.
/
A\ f\
n
91 U U U U U W° ° 7 '^^^VsVe'Tz
I
•/
M
ml
r
f
78 79 '80 «1 82 '83 B4 •& t6 B7 '88 '89 90 91
Table35. Hectares of SAV by density category and percentage of the Tier III SAV
restoration target (495 hectares) are listed for 1970 to 1991 for CBP Segment
ET10 (Pocomoke River). There is no Tier I SAV restoration goal for this segment.
Sources: Anderson and Macomber, 1980; Batiuket al., 1992; Orth et al., 1985,
1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
Year (no bar = ground survey data not available)
Figure 92. Percentage of Maryland Department of Natural Resources SAV
Ground Survey Program stations sampled where SAV was observed for CBP
Segment ET9 (Big Annemessex River). Ground survey data were not available
for 1972,1989, and 1990.
Source: Chesapeake Bay Program, unpublished data c.
106
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Tangier Sound
Tangier Sound covers a large area of shallow
water habitat that includes the Honga River, Fish-
ing Bay, Bloodsworth,Southmarsh, Smith, Tangier,
and Great Fox islands, Little Annemessex River,
and Pocorhoke Sound. This segment is closely
coupled with the Lower Chesapeake Bay; both
segments include portions of the same regions
(e.g., Bloodsworth and Southmarsh islands).
Prior to 1971, SAV was very abundant in this
segment, growing extensively in the expansive
shoal areas. Ground survey teams from the Mary-
land Department of Natural Resources documented
the abundance of Z. marina and/?, maritima through-
out the segment. Submerged aquatic vegetation
was practically eliminated from the entire segment
after 1971. The distribution of Z. marina changed
dramatically during this period. Abundant through-
out the segment prior to 1971, this species was
sighted only occasionally in the 1970s and 1980s.
The baywide aerial survey has documented a
significant increase in the distribution of SAV in
this segment over the last 13 years, from 1,645
hectares in 1978 to 5,461 hectares in 1991. This
change represents an increase of over 230 percent
(Figure 93, Table 36) and is coupled with the large
increase reported for the adjacent Lower Chesa-
peake Bay segment (see below). Almost 60 percent
of the SAV in Tangier Sound was classified as
dense (70-100 percent coverage) in 1991 compared
to less than 1 percent in 1978.
The Maryland Department of Natural Re-
sources ground survey reported vegetation at 100
percent of the stations in 1971. Reported percent-
ages of vegetated stations after 1971 ranged from
22 percent in 1974 to less than 2 percent by 1979.
The percentage of vegetated stations remained under
10 percent through 1986, increasing to 38 percent
by 1988 and ranging from 14 to 17 percent from
1989 through 1991 (Figure 95).
Y
The 1990 U.S. Fish and Wildlife Service clam
survey found SAV at 28 percent of 170 sampled
sites in the Honga River (Jordeetal., 1991). It was
particularly abundant along the eastern side of the
Honga River, although R. maritima was the only
species reported.
In the Honga River and around Bloodsworth
and Southmarsh islands, R. maritima was the domi-
nant species reported through ground surveys
conducted as part of the aerial survey program.
Both Z. marina and R. maritima were reported from
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
107
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Tangier Sound
5000-
4000-
3000-
2000-
1000-
ND ND ND ND ND ND ND ND
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 91
ND = NoData £3 70-100% Q 40-70% 0 10-40% • <10% • No Density Reported
Figure 93. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment EE3 (Tangier Sound),
the Tier I SAV restoration goal is 6,345 hectares.
Sources: Anderson and Macomber, 1980; Batiuk et al, 1992; Orth et al., 1979,1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
5-
o>
.0
CO
<
•5
2-
I-
o-
(2)
I
(3)
(4) (4)
ND ND 0 0
ND ND ND ND ND
'70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData Q Kd r~j D|p gj D|N | CHLA g TSS
Figure 94. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment EE3 (Tangier Sound).
No SAV habitat requirements met=0; no water quality data available = ND. Sufficient data for the following parameters were not available to calculate
growing season medians: Kd (1970-1975,1977-1985); TSS (1972,1973,1979,1981 -1985); CHLA (1970-1973,1979-1985); DIP (1970-1973,1979,
1981-1985); and DIN (1970,1972,1973,1979,1981 -1985). Numbers of SAV habitat requirements with growing season medians are shown above
bars when some values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
108
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
~jm
^f\
jf\ 4\. W\ff\
Wm mmm[0\ -*f -*-fL*\f&m
— ULMJJLiL^cH. Ctm^mJJJJJji.
71 72 73 74 76 76 77 78 79 80 B1 8283848586 87 SB^'W 91
Year (no bar = ground survey data not available)
Tangier Sound
Year
70
71
TO
Id.
73
74
75
76
r
i
<10%
_
"
_
.
Hectares of SAV by — •
Density Category
10-40%
B
•
„
.
40-70%
m
-
_
.
1
70-100%
s
*
„
.
Segment
Total
_
-
m
.
% of Tier I
Restoration
Goal
.
-
m
.
%ofTnrW
Restoration
Goal
•
,
.
Figure 95. Percentage of Maryland Department of Natural Resources SAV _
Ground Survey Program stations sampled where SAV was observed for CBP
Segment EE3 (Tangier Sound). Ground survey data were not available for 1 972
Source: Chesapeake Bay Program, unpubi shed data c.
around Tangier, Smith, and Great Fox islands and
in Big Annemessex River and Pocomoke Sound.
The only survey to report Z. marina north of Smith
Island was the Maryland Department of Natural
Resources ground survey. The survey reported this
species at several locations in the Honga River in
1991 and around Bloodsworth and Southmarsh
islands. The aerial survey shows that Fishing Bay,
vegetated with both R. maritima and Z. marina
prior to 1971, currently has only a small amount
of SAV.
78
79
'80
'81
'82
'83
'84
'85
'86
'87
'88
'89
•90
•91
46
-
-
-
•
-
50
140
120
225
-
105
355
281
375
-
.
.
-
-
285
475
548
599
-
442
657
819
557
-
-
-
-
-
879
1,190
1,084
895
-
914
790
1,158
2
-
.
.
•
-
993
948
1,675
1,592
-
3,045
3,047
3,202
1,645
-
.
-
-
-
2,207
2,753
3,427
3,311
•
4,506
4,849
5,461
26%
-
.
.
-
-
35%
43%
54%
51%
-
71%
76%
86%
5%
-
.
.
-
-
6%
8%
10%
9%
-
13%
14%
15%
Water quality conditions in Tangier Sound
from 1986 through 1988 met all five SAV habitat
requirements. From 1989 to 1991, only the total
suspended solids habitat requirement was not
achieved (Figure 94). Water quality in Tangier
Sound, as well as in the adjacent lower Chesapeake
Bay (Figure 106), has generally been suitable for
SAV survival and growth.
With increases in SAV distribution since 1978,
significant progress has been made towards the
Tier I restoration goal, increasing from 26 percent
to 86 percent by 1991 (Table 36). Achievement of
the Tier III restoration target has also increased
from 5 percent in 1978 to 15 percent in 1991.
Further expansion of SAV distributions beyond
one meter in depth will be dependent on further
improvements in water quality, particularly de-
Table 36. Hectares of SAV by density category and percentage of Tier I SAV
restoration goal (6,345 hectares) and Tier III SAV restoration target (35,686
hectares) are listed for 1970 to 1991 for CBP Segment EE3 (Tangier Sound). In
1978,665 hectares of SAV were mapped for which no density category was
reported but were included in the segment totals.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al., 1979,
1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
creases in total suspended solids concentrations
and light attenuation.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
109
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Potomac River
The Potomac River historically supported dense
stands of native SAV along its entire length. In
addition, several exotic species have appeared during
the past 70 years (Carter et al., 1983; Haramis and
Carter, 1983; Orth and Moore, 1984; Stevenson
and Confer, 1978; Stevenson and Staver, in press),
Today, the Potomac River is the only major western
shore tributary with SAV in each of its three major
segments, although the vegetation occurs at a some-
what reduced level in the lower Potomac River
segment.
One of the earliest accounts of SAV distribu-
tion comes from Currming et al. ( 1 9 1 6) who reported
dense SAV beds on th e margins of the upper Potomac
River below Washington, DC in the early 1900s.
Much native SAV in the tidal fresh and oligohaline
portions was gone by the late 1930s. Many past
surveys have shown that SAV in the middle Potomac
River, especially in and adjacent to Port Tobacco
River and Nanjemoy Creek, had fluctuating abun-
darce levels through the 1970s. Myriophyllum
spicatum, one exotic, that grows in this river, dra-
matically increased in the late 1950s, declined in
the mid-1960s, and occurred only in sporadic lo-
cations by the late 1960s. It is now one of the
doriinant species in the tidal fresh and the oligohaline
transition zones of the Potomac River.
*. -r/HV
'"VL v-^-'
HWV
"V **b'
c\ r> • ;
The Lower Potomac River, from the Route
301 Bridge south to the river mouth, often con-
tair ed pockets of SAV in various creeks and rivers.
These pockets have fluctuated widely in distribu-
tior . Anecdotal information indicated that Z. marina
was present in several areas of the Lower Potomac
River near the river mouth in the 1950s and 1960s
but has not been found since then. These obser-
vations are based on reports from the many ground
surveys conducted in the Lower Potomac River
from the 1950s through the early 1980s (Stevenson
and Staver, in press).
The U.S. Geological Survey and the U.S. Fish
and Wildlife Service have conducted one of the
most comprehensive surveys of the entire river
(Carter etal., 1983 and 1985a; Haramis and Carter,
1983). The survey found 15 species of SAV, with
the greatest concentration in the transition zone
(from Quantico, Virginia to the Route 301 Bridge),
especially in the Port Tobacco River, Nanjemoy
Creek, and adjacent shoreline in the Potomac River.
Very little SAV was found in the remainder of the
river either above or below the transition zone.
Subsequent surveys by the U.S. Geological Survey
110
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
documented changes in SAV populations, provid-
ing important supplementary ground survey
information for the aerial survey (Carter et al.,
1985b; Rybicki and Schening, 1990; Rybicki et al.,
1985, 1986, 1987, and 1988).
The aerial survey showed very little SAV in
the Lower Potomac River (Figure 96, Table 37).
Although 107 hectares were mapped in 1978, only
31 hectares were reported in 1987. Submerged
aquatic vegetation distribution increased to 84
hectares by 1991—a small increase compared to
the Tier III restoration target of approximately
18,000 hectares. This small amount of SAV was
found in Machodoc, Rosier, and Cuckold creeks
and in Wicomico and St. Mary's rivers. Ruppia
maritima was the only species found in the St.
Mary's River while M. spicatum was reported from
the other locations.
The Maryland Department of Natural Re-
sources survey reported only two years with vegetated
stations (1987 and 1988) since 1971 (Figure 98).
The 1990 U.S. Fish and Wildlife Service clam
survey found P. pusillus in the Wicomico River
(Jorde et al., 1991).
In the lower Potomac River, all five SAV
habitat requirements have been consistently achieved
since 1984 (Figure 97). Re-establishment of SAV
in the lower river segment appears to be limited by
a complex set of environmental and biological
factors that govern which species can become es-
tablished and grow in this segment. Despite the
abundance of SAV in the adjacent segments,
downriver spread of some species (e.g., H. verticillata)
may be prevented by salinities in the lower segment
that are above this species' tolerance limit. Other
species (e.g., Z. marina) may not recover in the
lower portion of the lower Potomac River segment
because there are no local beds of these species to
provide propagules for re vegetation. Existing Z.
marina beds are probably too far removed to pro-
vide either seeds or vegetative material.
Lower Potomac River
Year
70
71
72
73
74
75
76
77
78
79
•80
•81
'82
'83
•84
'85
'86
•87
>QQ
Do
•89
•90
•91
r
-
-
2
- '
-
-
-
-
0
9
1
2
12
22
18
Hectares of SAV by — ,
Density Category % of Tier* %ofTierl
Segment Restoration Restoration
10-40% 40-70% 70-100% Total Goal Goal
•
-
1
-
-
-
-
-
10
23
20
8
7
6
9
-
-
3
-
-
-
-
-
37
18
13
16
5
19
25
-
-
1
-
-
-
-
-
9
<1
3
5
17
5
32
-
-
107
-
-
-
-
-
56
51
37
31
41
52
84
-
-
38% <1%
-
-
-
- •
-
20% <1%
18% <1%
13% <1%
11% <1%
14% <1%
18% <1%
30% <1%
Table 37. Hectares of SAV by density category and percentage of Tier I SAV
restoration goal (282 hectares) and Tier III SAV restoration target (18,012
hectares) are listed for 1970 to 1991 for CBP Segment LE2 (Lower Potomac
River). In 1978,100 hectares of SAV were mappedfor which nodensity category
was reported but were inducted in the segment total.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al., 1985,
1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
100 -f
* 90-
!*-
? 70-
1 «-
| 50-
««•
C 3D'
•J 20-
0. 10-
'
(
r
< , ,W
717273747576777879'80'81182'83'84185B6«7B8189'9091
Year (no bar = ground survey data not available)
Figure 98. Percentage of Maryland Department of Natural Resources SAV
Ground Survey Program stations sampled where SAV was observed for CBP
Segment LE2 (Lower Potomac River). Ground survey data were not available
for 1986,1989, and 1990.
Source: Chesapeake Bay Program, unpublished data c.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
111
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Lower Potomac River
250-
200-
150^
O
100 -\
50-
ND ND ND ND ND ND ND ND
ND ND ND ND ND
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 "91
ND = No Data E3 70-100% D 40-70% 0 10-40% • <10% • No Density Reported
Figure 96. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment LE2 (Lower Potomac
River), the Tier I SAV restoration goal is 282 hectares.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al., 1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
5-
I 4
£
ja
cu
2-
o
1 "I
(4) (4) (4)
T:' T:! T-' T- T:! -! ^! T-!
(3) (2) (2)
0 0 0 ND
(1)
-•
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData Q Kd D DIP 0 DIN • CHLA • TSS
Figure 97. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment LE2 (Lower Potomac
River). No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters were not available
to calculate growing season medians: Kd (1970-1978,1981 -1983); TSS (1971 -1973,1981 -1983); CHLA (1970-1973,1981 -1983); DIP (1973,1981 -
1983); and DIN (1973,1981 -1983). Numbers of SAV habitat requirements with growing season medians are shown above bars when some values
were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
112
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Submerged aquatic vegetation in the Middle
Potomac River, from Quantico to just below the
Route 301 bridge, had increased only slightly from
1978 to 1987 (Figure 99, Table 38). It showed a
dramatic increase, however, between 1987 and
1989. Abundances remained high through 1991.
This large increase was due to the spread of H.
verticillata downriver to Aquia Creek, although
numerous other species have been found with H.
verticillata, including V. americana, N.
guadalupensis, E. canadensis, N. minor, C. demersum,
M. spicatum, Z. palustris, and H. dubia. Sub-
merged aquatic vegetation has been consistently
abundant in Port Tobacco River and Nanjemoy
Creek, as well as along the shoreline of the Potomac
River above and below each of these systems.
Along the south side of the river, SAV was abun-
dant adjacent to Mathias Point Neck. Species recorded
in this section of the river by ground surveys are
M. spicatum, V. americana, N. guadalupensis, E.
canadensis, N. minor, C. demersum, Z. palustris,
P. perfoliatus, P. pectinatus, and P. crispus.
In the Middle Potomac River, the Maryland
Department of Natural Resources ground survey
reported only two years with vegetated stations
(1980 and 1991) since 1971 (Figure 101). The 1990
U.S. Fish and Wildlife Service clam survey found
only V. americana in the Port Tobacco River and
Nanjemoy Creek, although the diversity of SAV is
high there (Jorde et al., 1991).
Submerged aquatic vegetation in the Upper
Potomac River has shown the most remarkable
increase compared to any other segment in Chesa-
peake Bay (Figure 102, Table 39). The Maryland
Department of Natural Resources ground survey
reported no SAV between 1972 and 1977 (Figure
104). Although the U.S. Geological Survey re-
ported sparse populations of SAV between 1978
and 1981 (Haramis and Carter, 1983), the aerial
survey recorded no SAV in 1978. In 1984, 622
hectares of SAV were mapped in the aerial survey,
a result of the rapid spread of//, verticillata as well
as some other native species downriver from Wash-
Middle Potomac River
Ye*
70
71
72
73
74
75
76
77
78
79
•80
SI
•82
'84
•85
•86
'87
•88
"89
•90
•91
r
-
-
0
-
-
-
-
25
12
27
18
-
69
96
103
Hectares of SAV by — ,
Density Category %ofTierl %ofTnrl
Segment Restoration Restoration
10-40% 40-70% 70-100% Total Goal Goal
•
-
281
-
-
-
-
62
70
123
58
-
119
206
63
-
-
0
-
-
-
-
93
215
117
53
-
81
242
153
-
-
0
-
-
-
-
42
145
163
378
-
1,005
824
1,153
-
-
281
-
-
-
-
222
442
430
507
-
1,274
1,368
1,472
-
-
15%
-
-
-
•
12%
23%
23%
27%
-
68%
74%
80%
>
-
4%
-
-
-
•
3%
6%
6%
7%
-
17%
18%
20%
Table 38. Hectares of SAV by density category and percentage of Tier I SAV
restoration goal (1,847 hectares) and Tier III SAV restoration target (7,443
hectares) are listed for 1970 to 1991 for CBP Segment RET2 (Middle Potomac
River). In 1978,100 hectares of SAV were mappedfor which no density category
was reported, but were included in the segment total.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al., 1985,
1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
Percent Stations Vegetated
ao^ssssasss
f
{
=1
71 72 73 74 75 76 77 78 79 W 31 182'83'84'85186187'88'89<90'91
Year (no bar = ground survey data not available)
Figure 101. Percentage of Maryland Department of Natural Resources SAV
Ground Survey Program stations sampled where SAV was observed for CBP
Segment RET2 (Middle Potomac River). Ground survey data were not available
for 1984 to 1987,1989, and 1990.
Source: Chesapeake Bay Program, unpublished data c.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
113
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
o>
2000
1600-
1200-
800-
400-
0-
Middle Potomac River
ND ND ND ND ND ND ND ND
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 -QO
ND = NoData [£3 70-100% D 40-70% 0 10-40% • <10% • No Density Reported
Figure 99. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment RET2 (Middle Potomac
River), the Tier I SAV restoration goal is 1,847 hectares.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al., 1979,1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
O)
4-
•5 3H
o-
0)
K
i
I 2H
1
•5
H
o
(1) (2) (1) (3)
00 0 ND 0
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData Q Kd Q DIP • CHLA • TSS
Figure 100. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment RET2 (Middle Potomac
River). No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters were not available
to calculate growing season medians: Kd (1970-1974,1981-1983,1985); TSS (1970-1973,1980-1985); CHLA (1970,1972,1973,1981-1985); and
DIP (1973,1981 -1985). Numbers of SAV habitat requirements with growing season medians are shown above bars when some values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
114 Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
2000-
>. 1600-
"5 1200-
co
CO
o 800-1
400-
Upper Potomac River
ND ND ND ND ND ND ND ND 0 ND ND ND ND ND
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 "91
ND = No Data ED 70-100% D 40-70% E2 10-40% • <10% • No Density Reported
ND = No Data 0 = Area surveyed, no SAV mapped
Figure 102. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment TF2 (Upper Potomac
River), the Tier I SAV restoration goal is 3,098 hectares. In 1991,2,049 hectares of SAV were reported.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al., 1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
6
£
•5 3
&•
B
DC
I
'$ 2H
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = No Data
D
D DIP
CHLA
TSS
Figure 103. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment TF2 (Upper Potomac
River). No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters were not available
to calculate growing season medians: Kd (1970-1974,1981-1985); TSS (1970-1973,1981-1985); CHLA (1972,1973,1981-1985); and DIP (1970,
1972,1973,1981-1985). Numbers ofSAVhabitatrequirementswithgrowing season mediansare shown above bars when some values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
115
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
ington, DC. Hydrilla verticillata was first found
in Dyke Marsh in 1982 and had spread rapidly
throughout the tidal fresh sections of the river by
1984.
The greatest change occurred between 1984
and 1986 when SAV distribution increased from
622 to 1,618 hectares, occupying most shallow
water areas down to Quantico. Some decline occurred
by 1989 (1,306 hectares) when H. verticillata was
no longer found in dense beds in either Piscataway
and Broad creeks or along the shoreline across from
these creeks. A significant increase took place
again between 1989 and 1991; 2,049 hectares were
mapped in 1991. The only large areas of shallow
water which did not support SAV throughout this
period were in Occoquan and Belmont bays, al-
though ground surveys did report M. spicatum and
H. verticillata in Belmont Bay in 1991. The Maryland
Department of Natural Resources SAV survey
reported vegetated stations only in 1988 and 1991
(Figure 104).
Submerged aquatic vegetation distribution in
the Upper Potomac River, from Quantico north to
Washington, DC has begun to stabilize in recent
years. Most shallow water habitat (one meter or
less) is now occupied by SAV. Species recorded
in this section of the river by ground surveys were
M. spicatum, V. americana, H. dubia, N.
guadalupensis, N. gracillima, E. canadensis, N.
minor, C. demersum, Z. palustris, P. pusillus, and
P. pectinatus, with H. verticillata, by far, the domi-
nant species.
Increases in SAV in the Upper Potomac River
are attributed, in part, to improvements in the Blue
Plains Wastewater Treatment Plant in Washington,
DC. These improvements have reduced total sus-
pended solids and phosphorus loadings significantly
and the plant now uses nitrification. In addition, the
dense beds of H. verticillata presumably influ-
enced water quality in the shoal areas. Barko
(unpublished data) has hypothesized that sediment
nutrient changes were factors in the decline. Carter
Upper Potomac River
Year
70
71
72
73
74
75
76
77
78
79
•80
«1
•82
•83
•84
•85
'86
'87
•00
OB
•89
•90
•91
r
<10%
-
-
71
62
147
41
165
72
80
Hectares of SAV by— |
Density Category
1MO% 40-70% 70-100%
-
-
294
279
286
50
266
246
230
-
-
105
309
89
44
82
137
120
•
-
152
748
1,096
1,447
793
1,187
1,619
% of Tier I % of Tier III
Segment Restoration Restoration
Total Goal Goal
0
-
622
1,398
1,618
1,582
. 1,306
1,642
2,049
0%
-
20%
45%
52%
51%
42%
53%
66%
0%
.
7%
17%
19%
19%
16%
20%
25%
Table 39. Hectares of SAV by density category and percentage of Tier I SAV
restoration goal (3,098 hectares) and Tier III SAV restoration target (8,304
hectares) are listed for 1970 to 1991 for CBP Segment TF2 (Upper Potomac
River).
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al., 1985,
1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
1001
I 80
g> 70-
I 50
5 40
«
I
10-
717273747576777879'80'81'82'83'84«5'86187'88
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
et al. (in press) found increases in plant coverage in the Lower Potomac River segment from 1984
when the mean Secchi depth was greater than 0.65 through 1991 (Table 37). In the middle river seg-
meters and decreases in the coverage when the ment, achievement of the Tier I restoration goal and
mean Secchi depth dropped below 0.65 meters. The Tier III restoration target increased from 12 percent
decline of SAV in several sections between 1987 to 80 percent and 3 percent to 38 percent, respec-
and 1989 resulted from meteorological changes lively, during the same period (Table 38). In the
(cool spring temperatures coupled with greater than upper river segment, achievement of the Tier I
normal spring rains) and poor water clarity (Carter restoration goal and the Tier III restoration target
et al., in press). increased from 20 percent to 66 percent and 7
percent to 25 percent, respectively (Table 39).
Despite the large increases in SAV in the
middle and upper Potomac River, mid-channel water
quality conditions were not suitable for SAV sur-
vival and growth until 1991. In most years, only
two of the SAV habitat requirements (generally
total suspended solids and chlorophyll a) were
routinely achieved (Figures 100 and 103).
The discrepancy between increasing SAV
distribution and abundance in these segments and
the unsuitable water quality conditions can be
attributed in part to differences in physiological
and morphological adaptations of the various spe-
cies. Hydrilla verticillata is a canopy-forming species
with minimum light requirements that are lower
than those of other SAV species in Chesapeake Bay
(Carter and Rybicki, 1990). Its leaves grow rapidly
to the surface and form a canopy that alters local
water quality, particularly water clarity. The result-
ant increased clarity allows other SAV species with
higher light requirements to colonize these envi-
ronments if they can compete with H. verticillata.
Dense SAV beds can also alter local water quality
by taking up nutrients from the water and by baf-
fling the waves and currents that resuspend bottom
sediments.
Achievement of the Tier I restoration goal
and the Tier III restoration target has been greatest
in the Upper and Middle Potomac River, the seg-
ments where SAV increased most dramatically.
Achievement of the Tier I restoration goal has not
exceeded 20 percent, while achievement of the Tier
III restoration target has been less than 1 percent
Trends in the Distribution, Abundance, and Habitat Quality of 117
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Lower Chesapeake Bay
The Lower Chesapeake Bay segment includes
a broad expanse of both the eastern and western
shores of the mainstem Bay. It extends southward
from just north of the Patuxent River to just above
the Rappahannock River mouth and northeast to
Tangier Island. This segment contains the third
highest amount of potential SAV habitat (Tangier
Sound has the largest, followed by the Middle
Potomac River segment) based on the Tier III
restoration target (Table 5). Along the western
shore, most of the potential habitat is located be-
tween Smith Point at the mouth of the Potomac
River and Windmill Point at the mouth of the
Rappahannock Rivsr. Along the Eastern Shore,
po:ential SAV habitat includes areas east of the
Hooper Islands (the Barren Island area), and por-
tions of Bloodswoith, South Marsh, Smith, and
Tangier islands.
Submerged aquatic vegetation abundance has
been gradually increasing in the Lower Chesa-
peake Bay segment, from 2,120 hectares in 1978
to 4,810 hectares in 1991, an increase of over 125
peicent (Figure 105; Table 40). Although SAV has
increased in all areas of this segment, the most
dramatic changes between 1978 and 1991 occurred
around Barren (142 to 1,587 hectares), Bloodsworth
and Southmarsh islands (2,571 to 4,706 hectares),
and Smith and Tangier islands (121 to 1,027 hect-
ares).
The Maryland Department of Natural Re-
sources ground survey reported the percentage of
veg etated stations fluctuated between 0 percent and
10 percerit between ] 971 and 1988, increased from
0 percent to 15 percent from 1988 to 1990, and then
declined to 3 percerit by 1991 (Figure 107).
Four species have been documented in this
segment. Zostera marina and R. maritima were the
most commonly reported species and P. pectinatus
and Z. palustris occurred less frequently. Follow-
ing the decline of SAV in the 1970s, only R.
maritima was reported from areas north of Smith
Island; it appears that Z. marina was completely
eliminated from these areas. Only in 1990 did the
Maryland Department of Natural Resources ground
survey report Z. marina from several locations
around Bloodsworth Island.
Along the western shore, only two species (Z.
marina and R. maritima) have been reported. This
area contained abundant SAV in the late 1960s,
although levels declined in the 1970s. The Fleets
Bay area just above Windmill Point was examined
118
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Lower Chesapeake Bay
5000 -i
4000-
M- 3000
o
& 2000-
0>
1000-
ND ND ND ND ND ND ND ND
ND ND ND ND ND
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 -90 91
ND = NoData E3 70-100% D 40-70% E3 10-40% • <10% • No Density Reported
Figure 105. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment CBS (Lower Chesapeake
Bay), the Tier I SAV restoration goal is 6,309 hectares.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Orth et al., 1979,1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND. No Data D Kd D DIP E2 DIN • CHLA • TSS
Figure 106. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment CBS (Lower Chesapeake
Bay). No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters were not available
to calculate growing season medians: Kd (1970-1975); TSS (1971-1973); CHLA (1970-1973); and DIP (1972,1973). Numbers of SAV habitat
requirements with growing season medians are shown above bars when some values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
119
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
100 -/
•o *•
€ 80-
§> 70-
I
> 60-
•
550-
5 40- "
n
£ x-
V
o 20-
"" 1° J ffytfo^4faq~£qvjlM)w
71 72 73 74 75 76 77 78 79 BO B1 B2 83 B4 85 W B7 38 89 90 91
Year (no bar = ground survey data not available)
Figure 107. Percentage of Maryland Department of Natural Resources SAV
Ground Survey Program stations sampled where SAV was observed for CBP
Segment CBS (Lower Chesapeake Bay). Groundsurvey data were not available
for 1971 and 1972.
Source: Chesapeake Bay Program, unpublished data c.
from 1937 to 1978. Submerged aquatic vegetation
increased from 1 90 hectares in 1 937 to 543 hectares
in 1969, dropping to 73 hectares in 1978 (Orth et
al., 1979). Submerged aquatic vegetation in the
section from Windmill Point at the mouth of the
Rappahannock River to Smith Point at the mouth
of the Potomac River has been generally increas-
ing — from 363 hectares in 1978 to 635 hectares in
1991. In addition, a small but expanding bed (2.2
hectares in 1991) of Z. marina and R. maritima in
Fleets Bay is notable because it is situated in rela-
tively deep (two meters at mean low water) water.
Four of the five SAV habitat requirements
were oenerallv met after 107S until 1084 The
Lower Chesapeake Bay
r Hectares of SAV by — i
Density Category % of Tier 1
Segment Restoration
Year <10% 1MO% 40-70% 70-100% Total Goal
70
71
72
73
74
75
76
77
78 352 352 1,248 0 2,120 34%
79
•80
•81
•82
113
•84 67 444 476 2,144 3,131 50%
"85 112 751 925 1,723 3,511 56%
«6 161 496 610 2,610 3,877 61%
«7 160 515 299 3,008 3,982 63%
"88
'89 279 439 619 3,356 4,693 52%
•90 669 1,431 1,368 1,,512 4,980 79%
•91 118 1,168 1,211 2,313 4,810 76%
% of Tier III
Restoration
Goal
14%
21%
23%
26%
26%
22%
33%
.32%
Table 40. Hectares of SAV by density category and percentage of Tier I SAV
restoration goal (6,309 hectares) and Tier III SAV restoration target (15,083
hectares) are listed for 1 970 to 1 991 for CBP Segment CBS (Lower Chesapeake
Bay). In 1 978, 1 68 hectares of SAV were mapped for which no density category
was reported but were inducted in the segment total.
Sources: Anderson and Macomber, 1 980; Batiuk et al., 1 992: Orth et al., 1 979,
1985, 1986, 1987, 1989, 1991, and 1992; Orth and Nowak, 1990.
improving water quality of the late 1970s and early
1980s (towards the meeting of all five SAV habitat
requirements) parallels the increasing trend of SAV
distribution for this region of the mainstem Bay.
Water quality in this segment has been suitable for
SAV survival and growth since 1984 when all five
SAV habitat requirements were met (Figure 106).
With the large increase in SAV from 1978 to
1991, the percent achievement of the Tier I resto-
ration goal and the Tier III restoration target has
increased from 34 percent to 76 percent and from
14 percent to 32 percent, respectively (Table 40).
120
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Rappahannock River
This region includes the Rappahannock and
Piankatank rivers and a small portion of Milford
Haven. Submerged aquatic vegetation was present
primarily in the lower Rappahannock and Piankatank
rivers in 1971 (1,123 hectares), with beds consist-
ing of both Z. marina and/?, maritima (Figure 108,
Table 41). By 1974, however, only 33 hectares
were reported. No more than 75 hectares were
reported in the Lower Rappahannock River seg-
ment until after 1986. From 184 hectares in 1987,
SAV distribution increased to 612 hectares in 1989
and then declined to 316 hectares by 1991.
No SAV has been reported from the aerial
survey in the Middle and Upper Rappahannock
River segments over the last 20 years (Figures 110
and 112; Tables 42 and 43). A ground survey
conducted in 1978, however, found several species
in many small creeks at 27 locations (Orth et al.,
1979). Potamogeton crispus, Z. palustris, V.
americana, E. canadensis, C. demersum, N. guada-
lupensis, N. minor, and R. maritima were reported
as occasional to abundant in many of these areas.
Prior to 1971, historical analyses indicated
the continued presence of SAV from 1937 to 1971
in one area (Parrott Island) on the south shore of
the lower Rappahannock River (Orth et al., 1979).
The 350 hectares of SAV reported in 1960 had
declined to less than five hectares by 1974.
In the middle 1980s, portions of the lower
Rappahannock River and Piankatank River be-
came colonized with R. maritima. Although some
declines of this species occurred through 1991,
large monospecific stands still exist along the north
shore of the Rappahannock River from Towles
Point at the mouth of the Corrotoman River to
Carters Creek in the Corrotoman River and along
the north end of Gwynn Island at the mouth of the
Piankatank River.
Some areas of the lower Rappahannock and
Piankatank rivers are also being colonized by Z.
marina, both naturally and with transplants. Since
1984, the Virginia Institute of Marine Science
scientists have transplanted both whole plants and
seeds to several locations in both rivers (Orth,
unpublished data). The scientists have observed
transplant success just south of Carters Creek in the
Rappahannock River where Z. marina seeds were
broadcast into an area containing dense/?, maritima
in 1987. This 13-hectare bed now consists of both
species. In the Piankatank River, whole plants of
Z. marina were placed in an unvegetated area off
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged'Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
121
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
2000 -f
Lower Rappahannock River
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83
ND = NoOata £] 70-100% Q 40-70% £/} 10-40% fl <10%
'85 '86 '87 '88 '89 "90 91
H No Density Reported
Figure108. Hectares of SAVby density categoryfor all yearsforwhichaerialsurveydatawereavailable. For CBP Segment LE3(LowerRappahannock
River), the Tier I SAV restoration goal is 1,714 hectares.
Sources: Batiuk et al., 1992; Chesapeake Bay Program, unpublished data b; Orth et al., 1979, 1985, 1986, 1987, 1989, 1991 , and 1992; Orth and
Gordon, 1975; Orth and Nowak, 1990.
v>
.t
I
oc
~
15
•5
i-
E
5-
4-
3-
1-
0-
ND ND ND ND
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = No Data
D Kd
DIP
DIN
CHLA
TSS
Figure 109. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment LE3 (Lower
Rappahannock River). No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters
were not available to calculate growing season medians: Kd (1970-1974,1981 -1983); TSS (1970-1979,1981 -1983); CHLA (1970-1974,1980-1983);
DIP (1970-1974,1981-1983); and DIN (1970-1974,1981-1983). Numbers of SAV habitat requirements with growing season medians are shown
above bars when some values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
122
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Burtons Point—at the mouth of the river—between
1984 and 1986. By 1991, this SAV bed had ex-
panded to 15 hectares and also had been colonized
naturally with R. maritima. Transplants at two
other locations in the Rappahannock River (Parrott
Island and Belle Isle) and one site in the Piankatank
River (Healy Creek) have not survived for more
than two years.
Several areas have revegetated naturally with
Z. marina, most notably along the north shore of
the Rappahannock River at Windmill Point. Part
of the bed at Windmill Point is in the western Lower
Chesapeake Bay segment. This bed, which also
contains R. maritima, had expanded to 13 hectares
by 1991.
Water quality conditions in the lower Rappa-
hannock and Piankatank rivers have been generally
suitable for SAV survival and growth since 1984,
with all five SAV habitat requirements met from
1984 to 1989 (Figure 109). Between 1975 and
1980, only the light attenuation coefficient and
chlorophyll a habitat requirements were consis-
tently met.
In the Middle Rappahannock River, only the
chlorophyll a, dissolved inorganic nitrogen, and
dissolved inorganic phosphorus SAV habitat re-
quirements were generally met between 1984 and
1991 (Figure 111). No more than three SAV habitat
requirements were met during any one year. Prior
to 1983, two or fewer SAV habitat requirements
were met during any one year, with only the chlo-
rophyll a habitat requirement met consistently from
1975 to 1979.
/
Water quality conditions were unsuitable for
SAV survival in the Upper Rappahannock River
over the 15-year data record (Figure 113). From
1975 to 1979, only the chlorophyll a habitat re-
quirement was consistently met. Between 1986 to
1991, chlorophyll a and dissolved inorganic phos-
phorus were the only requirements achieved.
Lower Rappahannock River
r Hectares of SAV by —i
Density Category % of Tier I % of Tier HI
' Segment Restoration Restoration
Year <10% 1040% 40-70% 70-100% Total Goal Goal
70
71
72
73
74
75
76
77
78
79
•80
•81
•82
B3
•84
•85
•86
•87
*QQ
00
•89
•90
•91
-
-
24
-
0
0
-
-
<1
8
0
35 .
47
<1
<1
-
•
38
-
0
0
•
-
13
<1
<1
44
278
125
141
•
-
13
-
0
0
-
-
2
<1
8
80
226
225
79
-
-
0
-
<1
1
•
-
1
2
3
25
61
50
96
1,123
33
-
75
-
<1
1
-
-
17
12
12
184
612
401
316
65% 12%
2% <1%
•
4% <1%
-
<1% <1%
<1% <1%
-
-
<1% <1%
<1% <1%
<1% <1%
11% 2%
35% 7%
23% 4%
18% 3%
Table 41. Hectares of SAV by density category and percentage of Tier I SAV
restoration goal (1,714 hectares) and Tier III SAV restoration target (9,342
hectares)arelistedfor1970to1991forCBP Segment LE3(LowerRappahannock
River).
Sources: Batiuketal.,1992;ChesapeakeBayProgram, unpublished datab;0rth
etal., 1979,1985,1986,1987,1989,1991, and 1992; Orthand Nowak, 1990.
Submerged aquatic vegetation has not been
reported through the baywide aerial survey in the
Middle and Upper Rappahannock River segments
where there has been no progress in achieving the
tiered restoration goals and targets (Tables 42 and
43). With the recent increases in SAV in the lower
Rappahannock and Piankatank rivers, however, the
percent achievement of the Tier I restoration goal
and the Tier III restoration target has increased
from less than 1 percent to 18 percent and from less
than 1 percent to 3 percent, respectively, from 1984
to 1991 (Table 41).
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
123
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Middle Rappahannock River
>
CO
"o
CO
2?
ss
o
Q)
100-
90-
80-
70-
•
60-
50-
40-
30-
20-
10-
•
ND 0 ND ND 0 ND ND ND 0 ND 0 0 ND ND 0 0 0 0 ND 0 0 0
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 "90
70-100% G 40-70% H 10-40% • <10% • No Density Reported
[J 40-70%
ND = No data
E) 10-40% • <10%
0 = Area surveyed, no SAV mapped
Figure 110. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment RETS (Middle
Rappahannock River), there is no Tier I SAV restoration goal.
Sources: Batiuk et al., 1992; Chesapeake Bay Program, unpublished data b; Orth et al, 1979, 1985, 1986, 1987, 1989, 1991, and 1992; Orth and
Gordon, 1975; Orth and Nowak, 1990.
5H
tr
m
- 3H
£l
CD
>
(A
"5
|
2-
1-
0-
ND ND ND ND
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData Q Kd Q D|p r^ D)N | CHLA • TSS
Figure 111. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment RETS (Middle
Rappahannock River). No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters were
not available to calculate growing season medians: Kd (1970-1974,1981 -1983); TSS (1970-1983); CHLA (1970-1974,1980-1984); DIP (1970-1974,
1980-1983); and DIN (1970-1974,1980-1983). Numbers of SAV habitat requirements with growing season medians are shown above bars when
some values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
124
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Upper Rappahannock River
>
CO
•5
100-
90-
80-
70-
•
60-
50-
40-
30-
20-
10-
ND 0 ND ND 0 ND ND ND 0 ND 0 0 ND ND 0 0 0 0 ND 0 0 0
70 71 72 73 74 75 76 77 78 79 BO B1 "82 B3 -84 B5 B6 "87 B8 B9 '90 91
EH 70-100% D 40-70% 0 10-40% • <10% • No Density Reported
ND = No data 0 = Area surveyed, no SAV mapped
Figure 112. Hectares of SAV by density category forall years for which aerial survey data were available. For CBP Segment TF3 (Upper Rappahannock
River), there is no Tier I SAV restoration goal.
Sources: Batiuk et al., 1992; Chesapeake Bay Program, unpublished data b; Orth et al., 1979,1985,1986,1987,1989,1991, and 1992; Orth and
Gordon, 1975; Orth and Nowak, 1990.
4-
O)
8
•5 3H
cr
cc
2-
co
"o
I H
(3)
(3) (3)
(3) (3) (3) (3)
(2) (3)
ND ND ND ND ND
Hill
ND ND ND
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData Q Kd Q DIP • CHLA • TSS
Figure 113. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment TF3 (Upper
Rappahannock River). No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters
were not available to calculate growing season medians: Kd (1970-1974,1981-1983); TSS (1970-1987); CHLA (1970-1974,1980-1984); and DIP
(1970-1974,1980-1983). Numbers of SAVhabitat requirements withgrowing season medians are shown above bars whensome values weremissing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
125
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Middle Rappahannock River
r Hectares of SAV by —,
Density Category % of Tier 1
1 Segment Restoration
Yar
70
71
72
73
74
75
76
77
78
79
•80 '
W
«2
•83
B4
85
•86
•87
B8
B9
•90
•91
<10%
.
-
-
•
-
-
•
-
0
-
0
0
.
-
0
0
0
0
-
0
0
0
1040%
.
-
-
•
-
-
-
-
0
-
0
0
.
-
0
0
0
0
-
0
0
0
40-711% 70-100%
.
•
•
•
•
,.
.
•
( 0
•
C 0
C 0
.
-
0 0
0 0
0 0
0 0
-
0 0
0 0
0 0
Total Goal
.
0
-
-
0
•
-
•
0
' -
0
0
.
-
0
0
0
0
-
0
0
0
%OfTwlll
Restoration
Goal
.
0%
-
-
0%
•
-
-
0%
-
0%
0%
.
-
0%
0%
0%
0%
.
0%
0%
0%
Upper Rappahannock River
r Hectares of SAV by
Density Category
Year
70
71
72
73
74
75
76
77
78
79
•80
•81
•82
•83
•84
'85
•86
•87
B8
•89
•90
•91
<10%
-
-
-
•
0
•
•
-
0
•
0
0
-
-
0
0
0
0
-
0
0
0
1(MO%
-
-
-
-
0
-
-
•
0
-
0
0
•
-
0
0
0
0
-
0
0
0
40-70%
-
-
-
•
0
-
-
-
0
-
0
0
•
-
0
0
0
0
-
0
0
0
1
70-100%
-
-
•
-
0
-
-
-
0
•
0
0
-
-
0
0
0
0
•
0
0
0
% of Tier 1
Segment Restoration
Total Goal
. .
0
•
-
0
-
-
-
0
-
0
0
-
•
0
0
0
0
-
0
0
0
% of Tier HI
Restoration
Goal
•
' -0%
-
-
0%
-
-
-
0%
-
0%
0%
•
-
0%
0%
0%
0%
•
0%
0%
0%
Table 42. Hectares of SAV by density category and percentage of Tier III SAV
restoration target (5,928 hectares) are listed for 1970 to 1991 for CBP Segment.
RET3(MiddleRappahannockR'ver).TrtereisnoSAVTierlSAV restoration goal
for tt is segment.
Sources: Batiuketal., 1992; Chesapeake BayProgram, unpublished datab;0rth
etai, 1979,1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
Table 43. Hectares of SAV by density category and percentage of Tier III SAV
restoration target (3,293 hectares) are listed for 1970 to 1991 for CBP Segment
TF3 (Upper Rappahannock River). There is no Tier I SAV restoration goal forthis
segment.
Sources: Batiuketal., 1992; Chesapeake Bay Program, unpublisheddata b; Orth
etal., 1979,1985,1986,1987,1989,1991, and 1992; Orth and Gordon, 1975;
Orth and Nowak, 1990.
126
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Western Lower
Chesapeake Bay
This segment covers a portion of the mainstem
Chesapeake Bay along the western shore from the
mouth of the Rappahannock River to the mouth of
the Back River. It includes a portion of both Wind-
mill Point, at the mouth of the Rappahannock
River, Milford Haven, and the Horn Harbor area,
just north of New Point Comfort which is at the
entrance to Mobjack Bay.
Both Z. marina and R. maritima have grown
in this segment throughout the last two decades,
steadily increasing from 1980 through 1991 from
180 to 555 hectares (Figure 114; Table 44). Over
the same period, the area of SAV categorized as
dense (70-100 percent) has continued to increase.
Two areas of interest are Windmill Point
(discussed above) and Milford Haven. Like many
areas, SAV was very abundant throughout Milford
Haven in the 1960s. Submerged aquatic vegetation
declined in the 1970s and occurred only in small
scattered patches. Virginia Institute of Marine Science
scientists transplanted submerged aquatic vegeta-
tion to Milford Haven in 1986 by using whole
plants of Z. marina. These transplants took hold
and grew through 1991. At the same time, a rapid,
natural expansion of the existing SAV beds oc-
curred along with the appearance of naturally
colonizing SAV in previously unvegetated areas.
Since 1984, all five SAV habitat require-
ments have been met in the Western Lower
Chesapeake Bay (Figure 115). The success of the
transplants since 1991 in Milford Haven, and natu-
ral expansion of existing SAV (off Windmill Point
and in Milford Haven), likely result from the long
period of water quality that was suitable for SAV
survival and growth.
The growth of SAV from 1980 to 1991 has
resulted in the percent achievement of the Tier I
restoration goal increasing from 23 percent to 71
percent and the percent achievement of the Tier HI
restoration target increasing from 6 percent to 19
percent (Table 44).
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
127
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
1000 -t
Western Lower Chesapeake Bay
ND ND ND ND ND ND ND ND
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 "86 '87 '88 '89
ND = No Data CD 70-100% G 40-70% E2 10-40% • <10% • No Density Reported
Figure 114. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment CB6 (Western Lower
Chesapeake Bay), the Tier I SAV restoration goal is 783 hectares.
Sources: Batiuk et a!., 1992; Chesapeake Bay Program, unpublished data b; Orth et al., 1979,1985,1986,1987,1989,1991, and 1992; Orth and
Gordon, 1975; Orth and Nowak, 1990.
£
5H
4H
tr
£ (
In
CO
> 2H
m
"o
.0-
Nl) ND ND ND ND ND ND ND
(2)
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData Q Kd Q DIP 0 DIN • CHLA • TSS
Figure 115. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment CB6 (Western Lower
Chesapeake Bay). No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters were
not available to calculate growing season medians: Kd (1970-1983); TSS (1970-1983); CHLA (1970-1977,1979-1983); DIP (1970-1983); and DIN
(1970-1977,1979-1983). Numbers of SAV habitat requirements with growing season medians are shown above bars when some values were
missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
128
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Western Lower Chesapeake Bay
Year
70
71
72
73
74
75
76
77
78
79
•80
'81
•82
•83
'84
'85
'86
•87
IQQ
OO
•89
•90
•91
r
<10%
-
-
0
-
6
0
-
-
27
0
0
59
8
0
14
Hectares of SAV by — ,
Density Category %ofTwl %<* Tier 111
' Segment Restoration Restoration
10-40% 40-70% 70-100% Total Goal Goal
-
-
31
-
57
46
-
-
38
18
95
48
106
178
152
-
-
269
•
48
57
-
-
70
260
181
49
16
31
81
-
-
0
-
68
128
-
-
174
60
54
107
278
303
308
-
•
300
-
179
231
•
-
309
338
330
263
408
512
554
-
•
38%
•
23%
29%
-
-
40%
43%
42%
34%
52%
65%
71%
-
-
10%
-
6%
8%
-
-
11%
12%
11%
'9%
14%
18%
19%
Table 44. Hectares of SAV by density category and percentage of Tier I SAV
restoration goal (783 hectares) and Tier III SAV restoration target (2,923
hectares) are listed for 1970 to 1991 for CBP Segment CB6 (Western Lower
Chesapeake Bay).
Sources: Batiuk et al., 1992; Chesapeake Bay Program, unpublished data b;
Orth et al., 1979,1985,1986,1987,1989,1991, and 1992; Orth and Nowak,
1990.
Trends in the Distribution, Abundance, and Habitat Quality of 129
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Ch ipter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Eastern Lower
Chesapeake Bay
This mainstem Bay segment covers the lower
Eastern Shore from the mouth of Chesapeake Bay
north to, but not including, Tangier Island and
Pocomoke Sound. The Eastern Lower Chesapeake
Bay segment includes many small tributaries that
enter the lower Bay, notably Cherrystone,
Mattawoman, Hungars.Nassawadox, Occohanock,
Nandua, Pungoteague, Onancock, and Chesconessex
crteks.
Submerged aquatic vegetation has gradually
increased in the Eastern Lower Chesapeake Bay
segment, from 1,630 hectares in 1980 to 3,743
hectares in 1991, a 130 percent increase (Figure
116; Table 45). Over the same time period, the area
of SAV categorized as dense (70-100 percent) has
continued to increas s from 19 percent to 41 percent
of the total SAV coverage. The predominant spe-
cie 5 reported are Z. marina and R. maritima, although
Z. palustris has been reported occasionally.
Extensive research and monitoring of SAV
has been conducted in the Vaucluse Shores area at
the mouth of Hungars and Mattawoman creeks
sin:e 1976, particularly between 1978 and 1981,
as part of the research phase of the Chesapeake Bay
Prc gram. Although r o segment-wide distributional
patterns were available until 1978, the distribution
of historical SAV was examined at Vaucluse Shores
from 1937 to 1978 (Orth et al., 1979).
Large dense b^ds of SAV grew at Vaucluse
Shores in 1937, only four years after the worldwide
eelgrass demise. The beds were relatively stable
unt.l 1972, although some reduction in total cov-
erage had occurred (Orthetal., 1979). Some losses
toox place between 1972 and 1978, probably re-
lated to the bay wide decline. Historical documentation
has revealed large shifts in sand bars and sand spits
over the past 40 years,, which led to changes in SAV
distribution. Some beds appeared to be covered
with sand, as bars and spits migrated, while some
new SAV habitat opened in areas formerly occu-
pied by these landforms.
Since 1985, all five SAV habitat require-
ments have been consistently met (Figure 117).
Over the historical water quality data record (pre-
1984, with the exception of 1979), the SAV habitat
requirements were met for all parameters for which
data were available.
The increase in SAV from 1980 to 1991 has
resulted in the percent achievement of the Tier I
restoration goal increasing from 35 percent to 81
130
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Eastern Lower Chesapeake Bay
5000 -f
ND ND ND ND ND ND ND ND
70 71 72 73 74 75 76 77 78 79 '80 '81
ND = No Data &\ 70-100% D 40-70% E2 10-40%
'83 '84 '85 '86 '87 '88 '89 '90 "91
<10% • No Density Reported
Figure 1 1 6. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment CB7 (Eastern Lower
Chesapeake Bay), the Tier I SAV restoration goal is 4,624 hectares.
Sources: Batiuk et al, 1992; Chesapeake Bay Program, unpublished data b; Orth et al., 1979, 1985, 1986, 1987, 1989, 1991 , and 1992; Orth and
Nowak, 1990.
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData Q Kd Q DIP 0 DIN • CHLA • TSS
Figure 117. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment CB7 (Eastern Lower
Chesapeake Bay). No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters were
not available to calculate growing season medians: Kd (1970-1977,1981 -1983); TSS (1971 -1977,1981 -1983); CHLA (1972-1974,1977,1981 -1983);
DIP (1972-1977,1979,1981-1983);andDIN(1972-1974,1976,1977,1979,1980-1983). Numbers of SAVhabitat requirements with growing season
medians are shown above bars when some values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
131
-------
Chapter 4: Regional Trends in SAV Distribution,
Ye*
7C
71
72
73
74
75
76
77
78
79
•80
•81
•82
'83
•84
•85
•86
'87
•88
•89
•90
•91
r
<10%
-
-
371
-
. 195
117
-
-
234
464
718
593
-
451
422
491
Abundance, and Habitat Quality
Eastern Lower Chesapeake Bay
Hectares of SAV by —,
Density Categcry % of Tier 1 % of TV* 111
' Segment Restoration Restoration
1040% 40-7)% 70-100% Total Goal Goal
-
-
1,072
-
603
572
-
-
937
739
565
574
-
660
946
1,151
-
•
9)7
as
9:13
as
$3
7514
7M
4JO
321
5£4
-
-
272
-
307
573
-
-
.892
552
779
771
-
1,439
1,412
1,538
-
•
2,282
-
1,630
2,195
-
•
2,686
2,708
2,796
2,719
-
3,040
3,111
3,743
-
•
49%
•
35%
47%
.
•
58%
58%
60%
59%
-
66%
67%
81%
-
-
19%
-
14%
19%
-
-
23%
23%
24%
23%
•
26%
26%
32%
Tat le 45. Hectares of SAV by density category and percentage of Tier I (4,624
hectares) SAV restoration gos I and Tier 111(11,803 hectares) SAV restoration
tarcet are listed for 1970 to 1991 for CBP Segment CB7 (Eastern Lower
Chesapeake Bay).
SOL rces: Batiuk et al, 1992; Chesapeake Bay Program, unpublished data b;
Orttietal.,1979,1985,1986,1937,1989,1991,and1992;OrthandNowak,1990.
percent, and that of the Tier III restoration target
increasing from 19 percent to 32 percent (Table
45). The continued natural expansion of existing
SAV is likely a result of the long period of suitable
water quality conditions.
132 Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Mob jack Bay
This segment includes Mobjack Bay (starting
at New Point Comfort) and its four tidal tributaries
(East, North, Ware, and Severn rivers), the Guinea
Marsh and Goodwin Island area at the mouth of the
York River, the Poquoson and Back rivers, the area
adjacent to Plum Tree Island, and Drum Island
Flats. Zostera marina and R. maritima are the
dominant species in this segment.
These areas are some of the most heavily
vegetated in Chesapeake Bay, both historically and
currently. Although some losses of SAV were evident
in the 1970s, they were not as extensive as those
in many other areas of the Bay. Large, dense stands
still occur in the above-mentioned sections. Exten-
sive quantitative data have been collected on the
distributional patterns of SAV in this segment over
the last two decades (Orth et al., 1979; Orth and
Moore, 1988).
Submerged aquatic vegetation declined from
1971 (3,197 hectares) to 1980 (2,457 hectares),
gradually increasing to 4,505 hectares by 1991—
the highest level recorded over the last two decades
(Figure 118; Table 46). In 1980, only 21 percent
of SAV was classified as dense (70-100 percent),
while 54 percent was in this category by 1991. The
most significant increases have occurred along the
York River sides of Guinea Marsh and Goodwin
Island.
Water quality conditions since 1984 have
generally been suitable for SAV survival and growth,
meeting all five SAV habitat requirements in five
of the last seven years (the total suspended solids
habitat requirement was not met in 1988 or 1989)
(Figure 119). These conditions represent an im-
provement from the mid-1970s to 1980 when water
quality conditions never met all five SAV habitat
requirements.
This segment has one of the highest percent-
age achievements of the Tier I restoration goal and
the Tier III restoration target of all segments in
Chesapeake Bay—76 percent and 36 percent, re-
spectively, in 1991. These numbers represent an
increase from the respective 1980 levels of 42
percent and 20 percent (Table 46).
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
133
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Mobjack Bay
5000 -i
70 71 72 73 74 75 76 77 78 79 "80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 "91
ND = NoData 01 70-100% Q 40-70% E2 1040% • <10% • No Density Reported
Figure 118. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment WE4 (Mobjack Bay),
the Tier I SAV restoration goal is 5,902 hectares.
Sources: Batiuk et al., 1992; Chesapeake Bay Program, unpublished data b; Orth et al., 1979,1985,1986,1987,1989,1991, and 1992; Orth and
Gordon, 1975; Orth and Nowak, 1990.
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
D Kd D DIP E3 DIN • CHLA • TSS
Figure 119. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment WE4 (Mobjack Bay).
No SAV habitat requirements met=0; no water quality data available = ND. Sufficient data for the following parameters were not available to calculate
growing season medians: Kd (1970-1974,1980-1983); TSS (1970-1983); CHLA (1970-1974,1980-1983); DIP (1970-1974,1980-1983); and DIN
(1970-1974,1980-1983). Numbers of SAVhabitat requirements with growing season medians are shown above bars whensome values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
134
Trends in the Distribution, Abundance, and Ha**"'. Ouality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Year
70
71
72
73
74
75
76
77
78
79
BO
B1
B2
B3
'84
'85
'86
B7
'RA
oo
•89
•90
•91
r
-
-
109
-
122
38
-
-
210
194
355
205
29
116
341
Mobjack Bay
Hectares of SAV by — ,
Density Category %ofTierl %dT«ll
' Segment Restoration Restoration
1(MO% 40-70% 70-100% Total Goal Goal
•
-
467
-
799
320
-
-
536
600
795
877
865
1,038
714
-
-
1,569
-
1,013
1,052
-
-
1,149
1,062
325
498
440
403
1,020
•
-
735
-
523
1,130
-
-
964
1,147
1,499
1,491
2,529
2,635
2,430
3,197
2,777
-
2,880
•
2,457
2,540
-
-
2,859
3,003
2,974
3,071
3,863
4,192
4,505
54%
47%
•
49%
-
42%
43%
-
-
48%
51%
50%
52%
65%
71%
76%
26%
22%
. •
23%
-
20%
20%
-
-
23%
24%
24%
'25%
31%
33%
36%
Table 46. Hectares of SAV by density category and percentage of Tier I SAV
restoration goal (5,902 hectares) and Tier III SAV restoration target (12,529
hectares) are listed for 1970 to 1991 for CBP Segment WE4 (Mobjack Bay).
Sources: Batiuk et al., 1992; Chesapeake Bay Program, unpublished data b;
Orth et al., 1979,1985,1986,1987,1989,1991, and 1992; Orth and Gordon,
1975; Orth and Nowak, 1990:
Trends in the Distribution, Abundance, and Habitat Quality of 135
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
York River
The York River historically supported dense
si ands of SAV (Z. marina and R. maritima) prima-
rily in the lower 25 kilometers of the river's mainstem
(Orth, 1976; Orth et al., 1979). An earlier decline
of Z. marina occurred in the 1930s and was related
to the worldwide decline of this species (Rasmus-
son, 1973 and 1977). An analysis of photographs
of two sites in the ..ower York River (the Mumfort
Islands and Jenkins Neck) taken between 1937 and
1971 showed SAV increasing at both sites from
1937 to 1960, with some decline between 1960 and
1971.
Despite concerns over the large losses of Z.
marina elsewhere in the world, this species was not
totally eliminated, with scattered beds of this plant
still present throughout the river. The expansion of
Z marina from these refuge populations probably
contributed to its rapid return, unlike other locali-
ties which have not been recolonized (e.g., the
shallow lagoons bohind the barrier islands of the
Dslmarva Peninsula).
Some of the decline of SAV along the south
shore in the Lowei York River in the 1960s may
hu.ve been related to construction of an oil refinery
ar d electric power plant. Dense stands of SAV
visible in photographs taken prior to construction
hi.ve either disappeared or were reduced in cover-
age during the construction phase (Orth, 1976).
Some of the losses were due to channel dredging
ard spoil disposal for the intake and outflow canals
from the power plant.
Almost nothing is known about the historical
di ;tributions of SAV in the tidal fresh and transition
zones, particularly in the broad shoal area along the
mninstem York River. No SAV has been mapped
in these Upper and Middle York River segments
over the last two decades. Submerged aquatic veg-
etation does exist as small fringing beds in many
of the brackish and tidal fresh marshes throughout
V
the area. Examination of marsh creeks at eleven
sites in the transition and tidal freshwater zone in
1978 revealed that SAV was present at all loca-
tions. Species recorded were Z. palustris, C.
demersum, E. canadensis, P. crispus, N.
guadalupensis, V. americana, and N. minor (Orth
et al., 1979).
The more recent decline of SAV in the 1970s
resulted in reduced coverage at or near the York
River mouth (Figure 120, Table 47) and its total
elimination from the middle and upper river seg-
ments (Figures 122 and 124; Tables 48 and 49). By
Trends in the Distribution, Abundance ~r.d Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Lower York River
250 -f
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '64 '85 '86 '87 '88 '89 "90 "91
ND = No Data ^ 70-100% D 40-70% 0 10-40% • <10% • No Density Reported
Figure 120. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment LE4 (Lower York
River), the Tier I SAV restoration goal is 309 hectares.
Sources: Batiuk et al., 1992; Chesapeake Bay Program, unpublished data b; Orth et al., 1979,1985,1986,1987,1989,1991, and 1992; Orth and
Gordon, 1975; Orth and Nowak, 1990.
OJ
tn
CO
i
5
V)
•5
"i
70 71 72 73 74 75 76 '77 78 79
ND = NoData [J Kd Q DIP E
0 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
DIN • CHLA • TSS
Figure 121. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment LE4 (Lower York
River). No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters were not available
to calculate growing season medians; Kd (1970-1974,1980-1983); TSS (1970-1983); CHLA (1970-1974,1980-1984); DIP (1970-1974,1980-1983);
and DIN (1970-1974,1980-1983). Numbers of SAV habitat requirements with growing season medians are shown above bars when some values
were missing.
Sources: Chesapeake Bay Program, 1993a and 1993.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
137
-------
Ciapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
1974, only 30 hectares of SAV were mapped in the
Lower York River. The distribution further de-
clined to 19 hectares by 1980. From 1980 to 1991,
submerged aquatic vegetation rebounded in the
Lower York River, from a low of 19 hectares to
65 hectares, with increases primarily in the region
from Gloucester Point to the river mouth.
The results of restoration efforts in the York
River parallel natural patterns of revegetation.
Restoration work with whole plants and seeds has
not been successful upriver from Gloucester Point,
suggesting that water quality rather than a lack of
sufficient propagules is preventing their re-estab-
lishment (Batiuk et al., 1992; Moore, unpublished
data). Natural revegetation and transplant survival
have been greatest downriver where existing beds
have rapidly expanded.
Water quality conditions in the Lower York
River have varied widely; all five SAV habitat
requirements were met in 1985 and only two were
met in 1991 (Figure 121). Available historical water
quality data indicate that conditions from 1975 to
1!>79 were unsuitable for SAV survival, with only
the chlorophyll a habitat requirement consistently
achieved.
In the Middle York River, water quality
conditions have generally met two or fewer SAV
habitat requirements, with only chlorophyll a con-
sistently met (Figure 123). Water quality conditions
in the Upper York River (Mattaponi and Pumunkey
rivers) have met all four SAV habitat requirements
shce 1988 although conditions were generally un-
suitable for SAV survival in previous years (Figure
125).
The increase in SAV in the Lower York River
segment from 1980 to 1991 'has resulted in an
in:rease in the per:ent achievement of the Tier I
restoration goal from 6 percent to 21 percent and
th; percent achievement of the Tier III restoration
target increasing from under 1 percent to 1 percent
Lower York River
I Hectares of SAV by —,
Density Category % of Tier I % of Tier in
1 ' Segment Restoration Restoration
Year <10% 1MO% 40-70% 70-100% Total Goal Goal
70
71
72
73
74
75
76
77
78
79
•80
•81
•82
•83
'84
'85
'86
«7
•88
•89
•90
•91
-
-
2
-
0
0
-
-
0
<1
0
0
-
4
8
<1
-
-
24
-
16
1
-
-
8
2
3
6
-
4
12
9
-
-
4
-
3
19
-
-
23
5
4
4
-
5
<1
17
-
-
0
-
0
0
-
•
3
24
22
33
•
43
60
40
245
31,
•
30
-
19
20
-
-
34
32
29
43
56
79
66
79%
10%
-
10%
-
6%
6%
-
-
11%
10%
9%
14%
•
18%
26%
21%
5%
-
<1%
-
<1%
<1%
-
-
<1%
<1%
<1%
<1%
-
1%
2%
1%
Table 47. Hectares ol SAV by density category and percentage of Tier I SAV
restoration goal (309 hectares) and Tier III SAV restoration target (4,822
hectares) are listed for 1970 to 1991 for CBP Segment LE4 (Lower York River).
Sources: Batiuk et al., 1992; Chesapeake Bay Program, unpublished data b;
Orthet al., 1979,1985,1986,1987,1989,1991, and 1992; Orth and Gordon,
1975; Orth and Nowak, 1990.
(Table 47). As SAV was not reported in the past
20 years in the Middle and Upper York River, no
progress has been made towards the tiered resto-
ration goals and targets in these segments (Tables
48 and 49).
Trends in the Distributer, Aoundance, and Habitat Quality of
S jbmerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Middle York River
>
CO
,^_
o
S
0
3:
100-
90-
80-
70-
"
60-
50-
40-
30-
20-
10-
ND 0 ND ND 0 ND ND ND 0 ND 0 0 ND ND 0 0 0 0 ND 0 0 0
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 "88 '89 "90 "91
[U 70-100% D 40-70% E2 10-40% •
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Upper York River
<
"o
CO
0>
o
0>
100-
90-
80-
70-
60-
50-
40-
30-
20-
10-
0
ND 0 ND ND 0 ND ND ND 0 ND 0 0 ND ND 0 0 0 0 ND 0 0 0
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 90 1
ND = NoData [Fj 70-100% Q 40-70% Q 10-40% | <10% | No Density Reported
Figure 124. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment TF4 (Upper York River),
there is no Tier I SAV restoration goal.
Sources: Batiuk et al., 1992; Chesapeake Bay Program, unpublished data b; Orth et al., 1979,1985,1986,1987,1989,1991, and 1992; Orth and
Gordon, 1975; Orth and Nowak, 1990.
o>
4-
a
£
'5 3
JT
0
cc
ro
| ,.
5
z
0J
ND ND ND ND ND
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoData D Kd Q DIP • CHLA • TSS
Figure 125. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment TF4 (Upper York
River). No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters were not available
to calculate growing season medians: Kd (1970-1974,1981-1983); TSS (1970-1987); CHLA (1970-1974,1979-1984); and DIP (1970-1974,1979-
1983). Numbers of SAV habitat requirements with growing season medians are shown above bars when some values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
140
Trends in th» Ciotribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Year
70
71
72
73
74
75
76
77
78
79
BO
B1
B2
•83
B4
•85
•86
•87
'88
'89
•90
•91
r
-
-
0
-
0
0
-
-
0
0
0
0
-
0
0
0
Middle York
Hectares of SAV by — i
Density Category
1 i
1040% 40-70% 70-100%
•
-
0
-
0
0
-
-
0
0
0
0
-
0
0
0
•
-
0
-
0
0
•
0
0
0
0.
-
0
0
0
-
•
0
-
0
0
-
-
0
0
0
0
-
0
0
0
River
% of Tier I %ofTierni
Segment Restoration Restoration
Total Goal Goal Year <
- ,70
0 - 0% 71
72
73
0 - 0% 74
75
76
77
0 0% 78
79
0 0% -so
0 - 0% tt
•82
. . -83
0 - 0% B4
0 • • 0% "85
0 0% -86
0 - . 0% -87
B8
0 0% -eg
0 0% -90
0 - 0% -9!
Upper York River
Hnrtrwnrnf CflWNr
— Fi6CuIeS OT oAV DJ ™ ™ ™n
Density Category % of Tier I % of Tier I
' Segment Restoration Restoration
10% 10-40% 40-70% 70-100% Total Goal Goal
0
0
.
0 0 ' 0 0 0
. .
00000
00000
-
.
0 0.0 0 0
0 00 0 0
00000
0 0 0 00
.
00 00 0
00000
00000
0%
0%
-
0%
-
0%
0%
-
-
0%
0%
0%
0%
•
0%
0%
0%
Table 48. Hectares of SAV by density category and percentage of Tier III SAV
restoration target (2,915 hectares) are listed for 1970 to 1991 for CBP Segment
RET4 (Middle York River). There is no Tier I SAV .restoration goal for this
segment.
Sources: Batiuk et al., 1992; Chesapeake Bay Program, unpublished data b;
Orth el al., 1979,1985,1986,1987,1989,1991, and 1992; Orth and Gordon,
1975; Orth and Nowak, 1990,
Table 49. Hectares of SAVby density category and percentageof theTierlllSAV
restoration target (1,614 hectares) are listed for 1970 to 1991 for CBP Segment
TF4 (Upper York River). There is no Tier I SAV restoration goal forthis segment.
Sources: Batiuk et al., 1992; Chesapeake Bay Program, unpublished data b;
Orth et al., 1979,1985,1986,1987,1989,1991, and 1992; Orth and Gordon,
1975; Orth and Nowak, 1990.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
141
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
James River
The James River and its two major tidal tribu-
taries, the Chickahominy and Appomatox rivers,
aru included in this section. Anecdotal evidence
and historical photography indicate that dense SAV
beds were found along the shores above the James
River bridge as late as the 1960s. The earliest
available photographs, from the late 1930s, show
what appear to be dense SAV beds in these same
sections of the river. Zostera marina was probably
the dominant species, although R. maritima was
most likely present also.
By 1991, the only SAV in the James River
mainstem was growing on the Hampton Flats in
the lower portion o:r the river (Figure 126, Table
50'—a small three-hectare bed of Z. marina. Al-
though the amount of SAV was greater in previous
years (particularly ir. 1978 when ten hectares were
reported), the total abundances represent only a
fraction of the potential SAV habitat (Tier III res-
toration target). Much of the Lower James River
has highly developed and modified shorelines (ship-
yards and naval piers) that will probably never
support SAV.
No SAV has been reported through the aerial
survey from the mair stem of the middle and upper
James River for the past two decades, except 13
hectares in 1986 in the middle river segment (Fig-
ures 128 and 130; Tables 51 and 52). The marsh tiered restoration goals and targets, given the vir.
creeks of the Chickahominy River, however, sup- tual absence of SAV in the James River during me
portedadiverseassernblageoffreshwaterSAV(V. past twenty yeafs (Tab]es 5Q 5j? and 52)
americana, N. guadulupensis, E. canadensis, N.
minor, and C. demersum) in 1978 (Orth et al.,
1979). Citizen SAV survey reports from the last
several years confirm the presence of many of these
species from the same marsh creeks.
Water quality conditions for all three James
River segments have generally met two or fewer
of the SAV habitat requirements (Figures 127,129,
and !31). There has been no progress towards the
142
T"--. js in the Distribution, Abundance, and Habitat Quality of
Subrrerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Lower James River
>
CO
"o
CO
TO
0
o>
100-
90-
80-
70-
60-
50-
40-
30-
20-
10-
X-jj
ND ND ND ND | 1 ND ND ND ^ ND 0 0 ND ND 0 0 0 ND ND fa* (f*\ f=n
70 71 72 73 74 75 76 77 78 79 '80 '81 '82 '83 '84 "85 B6 B? '88 "89 "90 91
d 70-100% D 40-70% 0 10-40% • <10% • No Density Reported
ND = No Data 0 = Area surveyed, no SAV mapped
Figure 126. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment LE5 (Lower James
River), the Tier I SAV restoration goal is 16 hectares.
Sources: Batiuk et al., 1992; Chesapeake Bay Program, unpublished data b; Orth et al., 1979,1985,1986,1987,1989,1991, and 1992; Orth and
Gordon, 1975; Orth and Nowak, 1990.
(D <«) (4) (4) (4) (4)
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 90 "91
ND = NoData Q Kd D DIP 0 DIN • CHLA • TSS
Figure 127. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment LE5 (Lower James
River). No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters were not available
to calculate growing season medians: Kd (1970-1973,1981 -1983); TSS (1970-1979,1981 -1983); CHLA (1970-1974,1980-1984); DIP (1970-1974,
1981-1983); and DIN (1970-1974,1981-1983). Numbers of SAV habitat requirements with growing season medians are shown above bars when
some values were missing.
Sources: Chesapeake Bay Program, 1993aand 1993b.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
143
-------
Cnapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Yer
70
71
72
73
74
75
76
77
78
79
•80
31
•82
•83
34
B5
•86
•87
wfl
(XJ
'89
•90
•91
Lower James River
r Hectares of SAW by — ,
Density Category %ofTierl %ofTwHI
1 Segment Restoration Restoration
<10% 1040% 40-711% 70-100% Total Goal Goal
•
•
4
•
0
0
-
-
0
0
0
0
0
0
0
-
•
5
•
0
0
-
-
0
0
0
3
0
0
0
-
<'
-
0
0
-
-
0
0
0
0
0
0
3
-
-
0
-
0
0
-
•
0
0
0
0
4
3
0
8
-
10
-
0
0
•
•
0
0
0
3
4
3
3
50%
-
63%
•
0%
0%
-
-
0%
0%
0%
0%
11%
19%
17%
<1%
•
<1%
-
0%
0%
-
-
0%
0%
0%
0%
<1%
<1%
0%
Year
70
71
72
73
74
75
76
77 .
78
79
•80
'81
•82
•83
'84
'85
'86
•87
|QO
88
•89
•90
•91
r
<10%
-
.
0
.
0
0
.
.
0
0
0
0
0
0
0
Middle James River
Hectares of SAV by — .
DensftyCategory % of Tier 1 % of Tier 11
Segment Restoration Restoration
1040% 40-70% 70-100% Total Goal Goal
-
.
0
.
0
0
-
-
0
0
0
0
0
0
0
-
.
0
-
0
0
.
.
0
0
0
0
0
0
0
-
.
0
-
0
0
.
.
0
0
13
0
0
0
0
0
0
.
0
.
0
0
.
.
0
0
13
0
0
0
0
0%
0%
.
0%
.
0%
0%
-
-
0%
0%
100%
0%
0%
0%
0%
: 0%
0%
.
0%
-
0%
0%
-
.
0%
0%
<1%
0%
0%
0%
0%
Tabte 50. Hectares of SAV by d snsity category and percentage of Tier I SAV
restoiation goal (16 hectares) and Tier III SAV restoration target (13,841
hecta -es) are listed for 1970 to 19D1 for CBP Segment LE5 (Lower James River).
Sources: Batiuketal.,1992; Chesapeake BayProgram,unpublisheddatab;Ortn
etal., 1979,1985,1986,1987,11)89,1991, and 1992; Orth and Gordon, 1975;
OrthandNowak,1990.
Table 51. Hectares of SAV by density category and percentage of Tier I SAV
restorationgoal(13hectares)andTierlllSAV restoration target(4,987hectares)
are listed for 1970 to 1991 for CBP Segment RETS (Middle James River).
Sources: Batiuk et al., 1992; Chesapeake Bay Program, unpublished data b;
Orth et al., 1979,1985,1986,1987,1989,1991, and 1992; Orth and Gordon,
1975; Orth and Nowak, 1990.
144
Trends in the Distribution, Abundance, and Habitat Quality of
Subrrurged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Middle James River
>
CO
*0
1
ro
1
100-
90-
80-
70-
•
60-
50-
40-
30-
20-
10-
,
•
ND 0 ND ND 0 ND ND ND 0 ND 0 0 ND ND 0 0 | 0 ND 0 0 0
70 71 72 73 74 75 76 77 78 79 '80 '81
E3 70-100%
'83 '84 '85 '86 '87 '88 '89 '90 91
D 40-70% E2 10-40% • <10% • No Density Reported
ND = No Data 0 = Area surveyed, no SAV mapped
Figure 128. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment RETS (Middle James
River), the Tier I SAV restoration goal is 13 hectares.
Sources: Batiuk et al, 1992; Chesapeake Bay Program, unpublished data b; Orth et al., 1979,1985,1986,1987,1989,1991, and 1992; Orth and
Gordon, 1975; Orth and Nowak, 1990.
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Upper James River
30 -f
25-
>
"5
to
15-
10-
5-
ND 0 ND ND 0 ND ND ND 0 ND 0 0 ND ND 0 0 0 0 ND 0 0
70 71 72 73 74 75 76 77 78 79 BO '81 B2 83 '84 B5 B6 '87 B8 '89 '90 91
E3 70-100% O 40-70% 0 10-40% • <10% • No Density Reported
ND = No Data 0 = Area surveyed, no SAV mapped
Figure 130. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment TF5 (Upper James
River), there is no Tier I SAV restoration goal.
Sources: Batiuk et al., 1992; Chesapeake Bay Program, unpublished data b; Orth et al., 1979,1985,1986,1987,1989,1991, and 1992; Orth and
Gordon, 1975; Orth and Nowak, 1990.
o>
=3
o-
4-
s
1 2H
55 H
1
o-
(3) (3) (3) (3) (3)
(3) (3)
ND ND ND ND ND
ND ND ND
(2) (3)
0 0
JLUI
^_J^HE_-^HM^^^^^^^^HHM_J^^^^—^^iK7
70 71 72 73 74 75 76 '77 78 79 '80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
ND = NoOata D Kd D DIP • CHLA • TSS
Figure 131. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment TF5 (Upper James
River). No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters were not available
to calculate growing season medians: Kd (1970-1974,1981-1983); TSS (1970-1987); CHLA (1970-1974,1980-1984); and DIP (1970-1974,1980-
1983). Numbers of SAV habitat requirements with growing season medians are shown above bars when some values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
146
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
Upper James River
,— Hectares of SAV by—,
Density Category % of Tier I % of Tier HI
1 ' Segment Restoration Restoration
Year <10% 1040% 40-70% 70-100% Total Goal Goal
70
71
72
73
74
75
76
77
78
79
•80
'81
'82
•83
'84
'85
'86
'87
'89
•90
'91
-
-
0
-
0
0
-
-
0
0
0
0
0
0
0
-
•
0
-
0
0
•
-
0
0
0
0
0
0
0
-
-
0
-
0
0
-
-
0
0
0
0
0
0
0
-
-
0
-
0
0
-
-
0
0
0
'0
0
0
0
0
0
-
0
-
0
0
-
-
0
0
0
0
0
0
0
0%
0%
-
0%
-
0%
0%
-
-
0%
0%
0%
'0%
0%
0%
0%
Table 52. Hectares of SAV by density category and percentage of the Tier 111 SAV
restoration target (5,780 hectares) are listed for 1970 to 1991 for CBP Segment
TF5(Upper James River).ThereisnoTierlSAVrestoration goal for thissegment.
Sources: Batiuketal., 1992; ChesapeakeBayProgram,unpublisheddatab;Orth
et al., 1979,1985,1986,1987,1989,1991, and 1992; Orth and Gordon, 1975;
Orth and Nowak, 1990.
Trends in the Distribution, Abundance, and Habitat Quality of 147
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trenis in SAV Distribution, Abundance, and Habitat Quality
Mouth of Chesapeake Bay
The Mouth oi' the Chesapeake Bay segment
encompasses the area from just below the mouth
of Back River to Cape Henry, including the small
embayments of the L ynnhaven River and Lynnhaven
and Broad bays. Zcstera marina and R. maritima
have been documented only in Broad Bay since
1984. The vegetation exists as small fringing beds
of sparse to moderate density with total abundance
ranging from 24 to 38 hectares between 1984 and
1991 (Figure 132, Table 53). No aerial overflights
of this area were flown prior to 1984, although it
is Jkely that these beds were present in the past.
Water quality conditions since 1984, as
measured in the irainstem Bay portion of this
segment, have met all five SAV habitat require-
ments with the except ion of 1987 when the chlorophyll
a requirement was not met (Figure 133). The 1991
SAV coverage in th;s segment is 28 percent and 1
percent of the Tier I restoration goal and Tier III
restoration target, respectively (Table 53). These
low percentages, des.pite good water quality in the
ma nstem Bay portion of this segment, indicate that
most of the potential SAV habitat is found in the
smaller, semi-enclosed tributaries with urbanized
watersheds where water quality conditions are likely
to be unsuitable for SAV survival.
U.S. EPA Headquarters Library
Mail code 3201
1200 Pennsylvania Avenue NW
Washington DC 20460
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chapter 4: Regional Trends in SAV Distribution, Abundance, and Habitat Quality
CO
•5
tn
a*
100-
90-
80-
60-
50-
40-
30-
20-
10-
Mouth of Chesapeake Bay
NO ND ND ND ND ND ND ND ND ND ND ND ND ND
70 71 72 73 74 75 76 77 78 79 '80 '81 ^ '83 '84 '85 '86 '87 '88 '89 -90
m 70-100%
Q] 40-70%
ND = No Data
10-40% | <10% H No Density Reported
0 = Area surveyed, no SAV mapped
Figure 132. Hectares of SAV by density category for all years for which aerial survey data were available. For CBP Segment CB8 (Mouth of the
Chesapeake Bay), the Tier I SAV restoration goal is 86 hectares.
Sources: Batiuk et al, 1992; Orth et al. 1985,1986,1987,1989,1991, and 1992; Orth and Nowak, 1990.
OJ
S"
tr
S
!5
ca
o>
1
70 71 72 73 74 75 76 '77 78 79
ND = NoData [] Kd Q DIP E
0 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91
DIN • CHLA • TSS
Figure 133. The number of SAV habitat requirements met over the SAV growing season from 1970 to 1991 for CBP Segment CB8 (Mouth of
Chesapeake Bay). No SAV habitat requirements met = 0; no water quality data available = ND. Sufficient data for the following parameters were
not available to calculate growing season medians: Kd (1970-1974,1981-1983); TSS (1970-1977,1981 -1983); CHLA (1970-1974,1981 -1983); DIP
(1970-1974,1978,1980-1983); and DIN (1970-1974,1976,1980-1983). Numbers of SAV habitat requirements with growing season medians are
shown above bars when some values were missing.
Sources: Chesapeake Bay Program, 1993a and 1993b.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
149
-------
Chapter 4: Regional Trends
in SAV Distribution, Abundance, and Habitat Quality
Mouth of Chesapeake Bay
Year
70
71
72
73
74
75
76
77
78
79
•80
•81
•82
•83
34
«5
•86
•87
'88
B9
•90
•91
r
.
-
-
-
-
-
-
-
•
-
• -
•
-
•
3
3
0
0
-
0
18
6
Hectares of SAV by
Density Category
10-40% 40-70%
.
•
-
•
•
-
•
•
-
-
-
-
-
-
3
3
31
23
-
20
5
10
-
-
-
-
•
-
-
-
-
-
-
-
28
26
12
18
•
17
5
8
1
70-100%
.
-
•
•
-
-
-
-
-
-
-
-
-
5
5
0
0
•
0
<1
0
Segment
Total
.
-
-
-
-
-
-
-
-
-
-
•
•
•
38
36
36
34
-
37
29
24
% of Tier 1
Restoration
Goal
.
-
•
-
-
-
-
•
•
-
•
•
-
•
44%
42%
42%
39%
-
43%
34%
28%
% of Tier III
Restoration
Goal
.
-
-
-
-
-
•
•
•
-
-
-
' -
-
2%
2%
2%
2%
-
2%
2%
1%
Table 53. Hectares of SAV by density category and percentage of Tier I (86
hectares) SAV restoration goal and Tier III (1,928 hectares) SAV restoration
target are listed for 1970 to 1991 tor CBP Segment CBS (Mouth of Chesapeake
Bay).
Sources: Batiuketal.,1992;0rthetal.,1985,1986,1987,1989,1991,and1992;
Orth and Nowak, 1990.
150 Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
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Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Appendix A
Appendix A. Sourcesd 1970-1983 Water Quality Data Used to Calculate SAV Growing Season Medians.
Plankton Ecology Project - conducted by W.R. Taylor, W.B. Cronin, and V. Grant, The Johns Hopkins
University, Chesapeake Bay Institute, from April 1969 through April 1971. This first phase of the project
(the Aesop cruises) was designed to characterize the nutrient and photosynthetic pigment distributions
from just south of the Susquehanna River's mouth to the mouth of the Bay. Later studies focused on
the role and significance of nitrogen species in plankton ecology, dissolved carbon release by Bay
phytoplankton, and the factors regulating primary productivity in the Bay.
Water Quality Survey of the Chesapeake Bay, 1979 - conducted by Michael Champ, American
University and the EPA Central Regional Laboratory, from May 1979 to October 1979. This survey
contains data in the mainstem Bay segments CB1, CB2, CBS, and CB4 (upper) and was conducted by
EPA to determine water quality conditions in the mainstem Chesapeake Bay and tidal Potomac River.
Chesapeake Bay Institute Data Bank Compilation of Cruise Data from 1949 through 1982 -
conducted by Donald Pritchard and staff of the Johns Hopkins University, Chesapeake Bay Institute
(CBI), from 1949 through 1982. This data set is a compilation of Chesapeake Bay mainstem cruise
data from the CBI data bank. There are over 100,000 observations of water temperature and salinity,
over 20,000 observations of pH, and more than 13,000 observations of dissolved oxygen, and current
data. There are many fewer records for chlorophyll, inorganic phosphate, and total phosphorus.
Ecological Effects of Nuclear Steam Electric Station Operations on Estuarine Systems - conducted
by J. A. Mihursky, D. R. Heinle, and W. R. Boynton, University of Maryland, from 1971 to 1978. This
data set provides an extraordinarily regular and complete record of dissolved oxygen, temperature,
salinity, and Secchi data over an extended period of time at a single location off Calvert Cliffs, Maryland.
Light Studies for the Chesapeake Bay - conducted by Michael Champ, American University, and
the EPA Central Regional Laboratory from May 21, 1979 to May 22, 1979. This data file contains
17 observations and is part of the data set collected for the light studies in the tidal Potomac River
and Chesapeake Bay.
Section 106 Ambient Water Quality Monitoring for Maryland Tidal Waters, 1965 to 1981 -
conducted by the Maryland Department of the Environment (formerly the Office of Environmental
Programs and the Water Resources Administration) from 1962-1981. The data set contains nutrient
(nitrogen and phosphorus), chlorophyll, and other water quality data from the Maryland portion of the
Chesapeake Bay.
Nutrient Cruises Upper Chesapeake Bay 1964 to 1966 and Patapsco River (Baltimore Harbor
Study) 1968 - conducted by R.C. Whaley, J.H. Carpenter, and R.L. Baker, The Johns Hopkins University,
Chesapeake Bay Institute, from 1964 to 1966. The purpose of the study was to inventory distributions
of the various forms of nitrogen and phosphorus. On these cruises, samples were also collected to
inventory the abundance and distribution of phytoplankton and zooplankton. Only chlorophyll concen-
trations and rates of primary production, however, are included in this data set.
Chesapeake Bay Institute Chesapeake Bay Transect Studies - conducted by J. Taft, The Johns
Hopkins University, Chesapeake Bay Institute, from 1977 to 1978. The data file contains physical-
Trends in the Distribution, Abundance, and Habitat Quality of A-1
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Appendix A
chemical, plant pigment, and nutrient data from a transect extending from the continental shelf to the
head of the Bay and into the tidal Susquehanna River.
Water Quality Survey of the Potomac Estuary, Summer and Fall 1979 - conducted by Michael
Champ, American University, and the EPA Central Regional Laboratory (formerly the Annapolis Field
Office), from May 1979 to October 1979. This data set contains water quality data collected in the
estuarine portion of the Potomac River.
Ecology of the Plankton of the Chesapeake Bay Estuary - conducted by R.W. Taylor and J.L. Taft,
The Johns Hopkin.5 University, Chesapeake Bay Institute, from 1975 to 1976. During the cruises,
measurements wen; taken of both water column and sediments throughout the mainstem Bay and at
the ocean station just beyond the Bay mouth.
Ciiesapeake Bay Nutrient Dynamics Study - conducted by J. L. Taft, The Johns Hopkins University,
Chesapeake Bay Institute, from 1980 to 1981. The overall objective of the study series was to enhance
the understanding of chemical and biological processes affecting nutrient fluxes in the Chesapeake Bay
estuarine environment. The synoptic study was conducted from July 8-17, 1980 in conjunction with
a circulation study covering the entire Bay from June 25 to July 29, 1.980. The nutrient process studies
were carried out at various times and locations depending of the requirements of the studies.
Chesapeake Bay Institute Data Bank 1981: Data from Tributary Cruises - conducted by the Johns
Hopkins University, Chesapeake Bay Institute principal investigators, from 1949 to 1980. This data
set is a compilation of historical temperature and salinity measurements for Chesapeake Bay tributaries.
Salinity and water temperature are the only complete parameters (>140,000 observations). There are
also approximately . 6,000 pH observations, 11,000 dissolved oxygen observations, and 1,200 inorganic
phosphate and chlorophyll observations.
Chesapeake Bay Institute Data Bank 1981: Nutrient Data from Tributary Cruises - conducted by
The Johns Hopkins University, Chesapeake Bay Institute principal investigators, from 1964 to 1980.
This data set is a compilation of historical nutrient values for the Chesapeake Bay tributaries. Included
are values for various forms of nitrogen and phosphorus as well as primary productivity data with
corresponding salinity and water temperature profiles.
Wa ter Quality of th
-------
Appendix A
oxygen, along the Rappahannock, York, and James rivers. Some nutrient data were also collected in
the late 1970s.
Historical Review of Water Quality and Climatic Data from Chesapeake Bay with Emphasis on
Effects of Enrichment - conducted by D.R. Heinle, C.F. D'Elia, J.L. Taft, J.S. Wilson, M. Cole-Jones,
A.B. Caplins, and E. Cronin. The investigators synthesized historical data from 1936 through the 1970s.
The water quality data in this set were compiled from many sources of historical Bay data by scientists
at the University of Maryland Chesapeake Biological Laboratory. The data collection effort was part
of a larger project to review past trends in Chesapeake Bay nutrient levels and to evaluate the Bay's
waters for nutrient enrichment.
Trends in the Distribution, Abundance, and Habitat Quality of A-3
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd(m-')
Med Rqmt Over N
• • • 0
• • • 0
• • t o
• « • 0
• • • 0
3.7 2.0 1.7 2
1.9 2.0 • 3
1.9 2.0 • 5
1.3 2.0 • . 8
1.6 2.0 • 21
1.8 2.0 • 9
• • • 0
• • • 0
• • • 0
1.6 2.0 • 7
1.5 2.0 • 14
1.5 2.0 • 13
1.6 2.0 • 14
1.5 2.0 • 14
1.6 2.0 • 14
1.8 2.0 • 13
1.2 2.0 • 14
CBP Segment CB1 -
TSS(mg/l)
Med Rqmt Over N
17.9 15 2.9 14
8.5 15 • 4
• • • 0
• • • 0
15.0 15 • 9
9.0 15 • 8
13.0 15 • 14
16.0 15 1.0 8
9.0 15 • 16
10.5 15 • 18
14.0 15 • 19
• • • 0
• • • 0
• • • 0
5.0 15 • 7
6.4 15 • 14
6.9 15 • 14
6.8 15 • 14
5.6 15 • 14
10.9 15 • 12
8.8 15 • 14
3.8 15 • 14
Northern Chesapeake
CHLa (ng/l)
Med Rqmt Over N
• • • 0
48.0 15.0 33.0 12
• • • 0
• • • o
22.5 15.0 7.5 9
24.4 15.0 9.4 26
24.2 15.0 9.2 16
12.0 15.0 • 8
15.0 15.0 • 19
15.0 15.0 • 34
11.7 15.0 • 17
• • • 0
• • • o
• • • 0
11.4 15.0 • 8
7.5 15.0 • 13
10.5 15.0 • 14
9.7 15.0 • 14
12.0 15.0 • 13
8.6 15.0 • 14
7.3 15.0 • 13
9.3 15.0 • 12
Bay (Tidal Fresh)
DIN(mg/l)
Med Rqmt Over N
• • '0
0.2595 • • 8
• • • 0
• • "0
0.4950 • • 9
0.8070 • • 26
0.7475 • • 16
0.7850 • • 8
0.9800 • -13
0.9530 • • 26
1.1190 • • 11
• • • 0
• • • 0
• • • 0
1.2612 • • 8
0.9340 • -14
0.9695 • « 14
0.9810 • • 14
1.0240 • • 14
1.4230 • • 14
1.1710 • • 14
0.9860 • • 14
DIP(mg/l)
Med Rqmt Over N
• • • 0
0.0150 0.0200 • 6
• • • 0
• • • 0
0.0100 0.0200 • 9
0.0150 0.0200 • 26
0.0250 0.0200 0.0050 16
0.0200 0.0200 • 8
0.0400 0.0200 0.0200 15
0.0130 0.0200 • 26
0.0100 0.0200 • 11
• • • 0
• • • 0
• • '0
0.0080 0.0200 • 8
0.0066 0.0200 • 14
0.0042 0.0200 • 14
0.0036 0.0200 • 14
0.0033 0.0200 • 14
0.0093 0.0200 • 14
0.0071 0.0200 • 14
0.0031 0.0200 • 14
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, I993a, 1993b.
-------
SAv Crowing Reason Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (m-1)
Med Rqmt Over N
o a , 0
• • » 0
• • • 0
• • • 0
• • • 0
• • • 0
2.7 2.0 0.7 5 •
3.0 2.0 1.0 13
2.2 2.0 0.2 26
2.6 2.0 0.6 46
2.4 2.0 0.4 " 26
2.9 2.0 0.9 7
2.4 2.0 0.4 6
2.4 2.0 0.4 7
2.1 2.0 0.1 19
2.9 2.0 0.9 27
2.9 2.0 0.9 26
2.4 2.0 0.4 28
1.8 2.0 • 28
2.7 2.0 0.7 28
2.4 2.0 0.4 26
1.8 2.0 • 28
CBP Segment CB2
TSS (mg/l)
Med Rqmt Over N
17.4 15 2.4 18
• • • 0
• • • 0
• • • 0
• • » 0
• • • 0
• • • 0
29.0 15 14.0 16
14.5 15 • 28
23.5 15 8.5 26
19.6 15 4.6 26
22.0 15 7.0 7
18.0 15 3.0 7
29.0 15 14.0 7
13.5 15 • 18
18.0 15 3.0 27
20.8 15 5.8 28
15.8 15 0.8 28
11.2 15 • 28
19.7 15 4.7 28
18.7 15 3.7 28
11.6 15 • 28
- Upper Chesapeake 1
CHL a (ug/l)
Med Rqmt Over N
21.4 15.0 6.4 4
30.2 15.0 15.2 22
• • • 0
• • • 0
« • • 0
36.0 15.0 21.0 3
15.0 15.0 • 7
18.0 15.0 3.0 17
17.1 15.0 2.1 40
18.0 15.0 3.0 77
15.0 15.0 • 33
67.8 15.0 52.8 7
19.2 15.0 4.2 3
9.6 15.0 • 1
10.7 15.0 • 18
9.0 15.0 • 26
9.0 15.0 • 28
10.1 15.0 • 28
4.5 15.0 • 24
3.7 15.0 • 26
5.2 15.0 • 25
4.5 15.0 • 21
3ay (Oligohaline)
DIN (mg/l)
Med Rqmt Over N
• • • 0
0.4895 • • 20
0.5830 • » 2
• • • 0
• • • 0
0.4750 • « 3
0.7060 • • 7
0.5830 • -17
0.7250 • » 21
0.8695 • • 53
0.7820 • » 15
0.4760 • • 7
1.0140 • • 7
1.1500 • • 7
0.9590 « • 20
0.6280 • • 27
0.6895 • • 28
0.7860 • • 28
0.7740 • • 28
1.1340 • • 28
1.0365 • • 28
0.4505 • • 28
DIP (mg/l)
Med Rqmt Over N
0.1070 0.0200 0.0870 1
0.0200 0.0200 • 13
0.0300 0.0200 0.0100 2
' • • 0
• • • 0
0.0100 0.0200 • 3
0.0400 0.0200 0.0200 7
0.0300 0.0200 0.0100 15
0.0300 0.0200 0.0100 24
0.0130 0.0200 • 53
0.0200 0.0200 • 15
0.0250 0.0200 0.0050 6
0.1000 0.0200 0.0800 6
0.2000 0.0200 0.1800 7
0.0110 0.0200 • 20
0.0118 0.0200 • 27
0.0111 0.0200 • 28
0.0104 0.0200 • 28
0.0134 0.0200 • 28
0.0145 0.0200 • 28
0.0100 0.0200 • 28
0.0094 0.0200 • 28
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a and 1993b.
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
c
Kd (m-1)
Med Rqmt Over N
1.9 1.5 0.4 56
1.6 1.5 0.1 57
5.8 1.5 4.3 6
0.9 1.5 • 6
0.7 1.5 • 1
0.6 1.5 • 11
1.1 1.5 • 73
2.4 1.5 0.9 77
1.9 1.5 0.4 74
1.9 1.5 0.4 73
1.4 1.5 • 86
1.2 1.5 • 7
1.2 1.5 • 8
1.0 1.5 • 5
1.3 1.5 • 37
1.5 1.5 • 52
1.6 1.5 0.1 50
1.5 1.5 • 56
1.3 1.5 • 56
1.5 1.5 • 54
1.6 1.5 0.1 54
1.5 1.5 • 56
BP Segment CBS - Up
TSS (mg/l)
Med Rqmt Over N
8.7 15 • 20
• • • 0
9.0 15 • 13
• • • 0
7.0 15 • 7
8.0 15 • 38
7.0 15 • 21
17.8 15 2.8 90
11.5 15 • 94
15.0 15 • 32
13.0 15 • 115
8.0 15 • 14
22.5 15 7.5 16
10.0 15 • 16
4.3 15 • 40
8.4 15 • 54
8.5 15 • 56
7.0 '15 -56
7.2 15 • 55
7.8 15 • 54
8.1 15 • 56
8.1 15 • 56
iper Central Chesapea
CHL a (ng/l)
Med Rqmt Over N
36.0 15.0 21.0 57
28.4 15.0 13.4 80
28.4 15.0 13.4 32
17.8 15.0 2.8 26
21.7 15.0 6.7 34
17.8 15.0 2.8 79
30.9 15.0 15.9 78
25.5 15.0 10.5 107
9.0 15.0 • 130
18.5 15.0 3.5 108
13.0 15.0 • 120
32.4 15.0 17.4 11
10.0 15.0 « 6
7.3 15.0 • 3
10.0 15.0 • 35
11.0 15.0 • 53
10.5 15.0 • 56
10.4 15.0 • 56
9.0 15.0 • 51
7.6 15.0 • 51
7.3 15.0 • 55
10.1 15.0 • 52
-------
001
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1Q70
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
c
Kd (m-1)
Med Rqmt Over N
• • • />
• • • 0
1.0 1.5 • 21
0.8 1.5 • 42
0.8 1.5 • 24
0.5 1.5 • 11
0.8 1.5 • 69
0.8 1.5 • 72
0.8 1.5 • 59
0.9 1.5 • 68
0.9 1.5 ' • 53
• • « 0
• • • 0
• • • o
0.8 1.5 • 40
0.9 1.5 • 69
0.8 1.5 • 65
0.8 1.5 • 69
0.9 1.5 • 69
1.0 1.5 • 66
1.0 1.5 • 69
0.9 1.5 • 69
BP Segment CB4 - Mi
TSS (mg/l)
Med Rqmt Over N
* n *r - -7
T.*/ U " I/
• • • 0
• • • 0
« « • 0
19.0 15 4.0 4
16.0 15 1.0 .9
13.0 15 • 36
18.0 15 3.0 46
9.0 15 • . 58
5.8 15 • 42
6.0 15 • 72
• • • 0
« • • 0
• • • 0
4.0 15 • 36
5.7 15 • 70
4.5 15 • 70
4.8 15 • 70
5.7 15 • 69
5.3 15 • 66
5.3 15 • 69
5.0 15 • 70
ddle Central Chesapea
CHL a (ug/l)
Med Rqmt Over N
. . • y
• • • o
• • • 0
31.5 15.0 16.5 4
19.5 15.0 4.5 4
16.5 15.0 1.5 15
13.8 15.0 • 67
13.8 15.0 • 73
9.0 15.0 • 110
11.9 15.0 • 98
12.5 15.0 • 63
• • • 0
• • » 0
• • • o
11.2 15.0 • 38
9.0 15.0 • 67
8.8 15.0 • 67
11.6 15.0 • 70
9.5 15.0 • 64
11.4 15.0 • 59
9.3 15.0 • 68
8.1 15.0 • 63
ke Bay (Mesohaline)
DIN (mg/l)
Med Rqmt Over N
U.l 029 0.1500 • 48
• • • 0
• • • 0
0.2755 0.1500 0.1255 4
0.2755 0.1500 0.1255 4
0.4890 0.1500 0.3390 10
0.2155 0.1500 0.0655 56
0.1200 0.1500 • 68
0.2310 0.1500 0.0810 61
0.3050 0.1500 0.1550 62
0.0860 0.1500 • 52
• • • 0
• • • 0
• • • 0
0.1425 0.1500 • 40
0.1125 0.1500 • 70
0.1006 0.1500 • 70
0.1124 0.1500 • 70
0.1440 0.1500 • 70
0.3598 0.1500 0.2098 66
0.1570 0.1500 0.0070 69
0.0520 0.1500 • 70
DIP (mg/l)
Med Rqmt Over N
0.0170 0.0100 0.0070 50
• • • 0
• • • 0
0.0200 0.0100 0.0100 4
0.0100 0.0100 • 4
0.0300 0.0100 0.0200 10
0.0300 0.0100 0.0200 56
0.0180 0.0100 0.0080 101
0.0200 0.0100 0.0100 62
0.0130 0.0100 0.0030 67
0.0200 0.0100 0.0100 52
• • • 0
• • • 0
• • • 0
0.0070 0.0100 • 41
0.0055 0.0100 • 69
0.0044 0.0100 • 70
0.0050 0.0100 • 70
0.0038 0.0100 • 70
0.0050 0.0100 • 66
0.0045 0.0100 • 69
0.0033 0.0100 • 69
(D
CL
JO
c •
2.
O>
Q. 5
V) T"
-1 X
&s
=• o>
5!o
cr c
c= o>
1^
5B o
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (m-1)
Med Rqmt Over N
• • • 0
• • • 0
• • « 0
• • » 0
• • • 0
• • t o
0.7 1.5 • 4
0.7 1.5 • 9
0.7 1.5 • 23
0.6 1.5 • 16
0.7 1.5 • 39
2.4 1.5 0.9 14
0.7 1.5 • 7
0.7 1.5 • 19
0.7 1.5 • 54
0.7 1.5 • 76
0.7 1.5 • 79
0.8 1.5 • 80
0.9 1.5 • 85
0.8 1.5 • 81
0.9 1.5 • 81
0.7 1.5 • 81
CBP Segment CBS
TSS (mg/l)
Med Rqmt Over N
4.0 15 • 19
• • • 0
• • • 0
• • • o
9.5 15 • 2
20.0 15 5.0 3
11.0 15 • 4
26.0 15 11.0 5
7.5 15 • 24
5.1 15 • 17
14.0 15 • 75
19.0 15 4.0 16
4.0 15 • 7
4.0 15 • 37
4.0 15 • 79
5.9 15 • 78
4.0 15 • 83
5.0 15 • 83
8.0 15 • 82
7.0 15 • 80
6.1 15 • 82
4.9 15 • 81
- Lower Chesapeake E
CHL a (ug/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • o
• • • 0
30.0 15.0 15.0 2
12.7 15.0 • 14
5.3 15.0 • 15
11.0 15.0 • 17
11.9 15.0 • 56
8.0 15.0 • 29
8.0 15.0 • 52
17.8 15.0 2.8 15
12.4 15.0 • 7
11.3 15.0 • 30
9.2 15.0 • 38
.5.6 15.0 • 77
6.8 15.0 • 80
8.4 15.0 • 83
10.6 15.0 • 82
9.6 15.0 • 70
9.1 15.0 • 77
6.0 15.0 • 76
Jay (Mesohaline)
DIN (mg/l)
Med Rqmt Over N
0.0392 0.1500 • 44
0.3514 0.1500 0.2014 12
0.3736 0.1500 0.2236 7
0.3084 0.1500 0.1584 7
0.2865 0.1500 0.1365 2
0.1792 0.1,500 0.0292 6
0.0602 0.1500 • 9
0.0660 0.1500 • 27
0.2268 0.1500 0.0768 31
0.2550 0.1500 0.1050 5
0.0439 0.1500 • 47
0.0800 0.1500 • 16
0.4230 0.1500 0.2730 7
0.3240 0.1500 0.1740 37
0.1125 0.1500 • 82
0.0547 0.1500 • 77
0.0695 0.1500 • 83
0.0511 0.1500 • 82
0.0383 0.1500 • 83
0.1440 0.1500 • 81
0.0726 0.1500 • 82
0.0291 0.1500 • 82
DIP (mg/l)
Med Rqmt Over N
0.0124 0.0100 0.0024 51
0.0062 0.0100 • 5
• • • 0
• • • 0
0.0150 0.0100 0.0050 2
0.0064 0.0100 • 6
0.0200 0.0100 0.0100 8
0.0030 0.0100 • 39
0.0200 0.0100 0.0100 30
0.0100 0.0100 • 5
0.0135 0.0100 0.0035 48
0.0062 0.0100 • 16
0.1000 0.0100 0.0900 7
0.0100 0.0100 • 37
0.0100 0.0100 • 81
0.0084 0.0100 • 76
0.0062 0.0100 • 82
0.0058 0.0100 • 82
0.0031 0.0100 • 85
0.0039 0.0100 • 81
0.0033 0.0100 • 82
0.0027 0.0100 • 82
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a, 1993b.
-------
c? Atr *~* • c<
ur*.* wiirwiiig ocaaun
f~\ Hi— »*_-!•
~ \£umii.y ivicuians
oegiiieiii ^ay/u io i>^i)
Year
ISA)
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
19S1
Kd (m-')
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • « 0
• • • 0
• i • 0
• • « 0
• • • 0
• • • 0
• t • o
0.9 1.5 • 15
0.7 1.5 • 33
0.6 1.5 • 44
0.9 1.5 • 43
0.8 1.5 • 40
0.8 1.5 • 36
0.9 1.5 • 34
0.7 1.5 • 35
Segment CB6 - West
TSS (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• « • 0
• t • o
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
13.0 15 • 16
6.0 15 • 43
5.0 15 • 44
7.0 15 • 44
11.5 15 • 40
14.9 15 • 36
9.0 15 • 36
9.0 15 • 35
ern Lower Chesapeak<
CHL a (ug/l)
Med Rqmt Over N
• • • 0
• t • o
• • • 0
• • • 0
• « • 0
• « • 0
• • • 0
• « • o
3.4 15.0 • 1
• . • 0
• • • 0
• « • 0
• t • o
• • • 0
8.9 15.0 • 16
5.5 15.0 • 43
6.9 15.0 • 44
8.4 15.0 • 43
7.7 15.0 • 40
5.8 15.0 • 36
10.6 15.0 • 36
6.4 15.0 • 36
3 Bay (Polyhaline)
DIN (mg/l)
Med Rqmt Over N
• • • 0
• • "0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
t • • 0
0.2020 0.1500 0.0520 1
« • • 0
• • • 0
• • • 0
• • • 0
• • • 0
0.0400 0.1500 • 16
0.0660 0.1500 • 43
0.1175 0.1500 • 44
0.0985 0.1500 • 44
0.0360 0.1500 • 40
0.0849 0.1500 • 36
0.0357 0.1500 • 36
0.0883 0.1500 • 36
DIP (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
0.0100 0.0200 • 16
0.0100 0.0200 • 43
0.0100 0.0200 • 44
0.0110 0.0200 • 44
0.0020 0.0200 • 40
0.0030 0.0200 • 36
0.0030 0.0200 • 36
0.0032 0.0200 • 36
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a and 1993b.
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
c
Kd (m -')
Med Rqmt Over N
• • • 0
• • • 0
• • • o
• « • o
• • • o
• • • o
• • • o
• • • o
0.7 1.5 • 4
0.7 1.5 • 6
0.7 1.5 • 12
• • • 0
• • • 0
• • • o
0.7 1.5 • 14
0.6 1.5 • 31
0.6 1.5 • 33
0.9 1.5 • 31
0.7 1.5 • 27
0.8 1.5 • 27
0.8 1.5 • 27
0.6 1.5 • 26
IBP Segment CB7 - EJ
TSS (mg/l)
Med Rqmt Over N
2.9 15 • 11
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• t • o
4.0 15 • 4
5.3 15 • 6
4.3 15 • 12
• • • 0
• • • 0
• • • 0
17.5 15 2.5 14
7.9 15 • 32
4.0 15 • 33
7.0 15 • 33
9.5 15 • 30
14.4 15 • 27
9.0 15 • 25
7.0 15 • 27
istern Lower Chesapet
CHL a (ug/l)
Med Rqmt Over N
0.5 15.0 • 11
3.5 15.0 • 9
• « • 0
• • • 0
• • • 0
9.8 15.0 • 3
3.5 15.0 • 4
• • • 0
6.3 15.0 • 14
19.0 15.0 4.0 12
10.0 15.0 • 20
• • • 0
• • • 0
• « « 0
8.3 15.0 • 14
4.5 15.0 • 32
6.1 15.0 • 33
10.8 15.0 • 33
6.6 15.0 • 30
5.1 15.0 • 27
9.1 15.0 • 27
5.9 15.0 • 27
ike Bay (Polyhaline)
DIN (mg/l)
Med Rqmt Over N
0.0420 0.1500 • 19
0.1078 0.1500 • 3
• • • 0
• • • 0
• • • 0
0.0308 0.1500 • 1
• • • 0
• • • 0
0.0953 0.1500 • 2
• • §0
• • "0
• • • 0
• • *0
• • • 0
0.0400 0.1500 • 13
0.0470 0.1500 • 32
0.1170 0.1500 • 33
0.0610 0.1500 • 33
0.0255 0.1500 • 30
0.0807 0.1500 • 27
0.0415 0.1500 • 27
0.1174 0.1500 • 27
DIP (mg/l)
Med Rqmt Over N
0.0062 0.0200 • 23
0.0124 0.0200 • 3
• • • 0
• • • 0
• • • 0
• • • 0
• • «0
• • « 0
0.0010 0.0200 • 1
• • "0
• • • 0
• • • 0
• • • 0
• • « 0
0.0100 0.0200 • 14
0.0100 0.0200 • 32
0.0100 0.0200 • 33
0.0110 0.0200 • 33
0.0020 0.0200 • 30
0.0030 0.0200 • 27
0.0030 0.0200 • 27
0.0037 0.0200 • 27
CO
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VTI owing oeasuii water vuaiuy ivieuians s>y oegmeni
10
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (m-1)
Med Rqmt Over N
• • • 0
• i • 0
• • • 0
• « • 0
• « • 0
1.3 1.5 • 3
1.2 1.5 • 6
1.3 1.5 • 4
0.9 1.5 • 3
0.9 1.5 • 9
0.7 1.5 • 7
• « • 0
• • • 0
• • • o
1.0 1.5 • 5
0.7 1.5 • 11
0.9 1.5 • 11
1.1 1.5 • 11
0.9 1.5 • 10
0.9 1.5 • 9
0.6 1.5 • 9
0.9 1.5 • 9
CBP Segment CBS -
TSS (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
6.1 15 • 2
5.4 15 • ' 3
4.0 15 • 3
• • • 0
• • • 0
• • • 0
8.5 15 • ' 5
4.6 15 • 11
7.0 15 • 11
7.9 15 . • 11
7.6 15 • 10
6.5 15 • 9
5.6 15 • 9
7.8 15 • 9
Mouth of Chesapeake
CHL a (tig/I)
Med Rqmt Over N
« • • 0
• « • 0
• • • o
• • • 0
• • • 0
2.3 15.0 • 1
5.6 15.0 • 2
11.1 15.0 • 4
11.0 15.0 • 5
10.5 15.0 • 8
7.0 15.0 • 4
• • • 0
• • • 0
• • • 0
9.3 15.0 • 4
4.2 15.0 • 11
6.5 15.0 • 11
15.1 15.0 0.1 10
4.5 15.0 • 10
4.9 15.0 • 9
6.2 15.0 • 9
4.7 15.0 • 9
Bay (Polyhaline)
DIN (mg/l)
Med Rqmt Over N
• « « 0
• • • 0
• • • o
• • • 0
• • • 0
.0.3533 0.1500 0.2033 2
• • • 0
0.1599 0.1500 0.0099 3
0.1020 0.1500 • 1
0.3399 0.1500 0.1899 3
• • • 0
• • « 0
• • • 0
• • • 0
0.0340 0.1500 • 5
0.0280 0.1500 -11
0.0700 0.1500 • 11
0.0341 0.1500 • 11
0.0306 0.1500 • 10
0.1193 0.1500 • 9
0.0649 0.1500 • 9
0.0638 0.1500 • 9
DIP (mg/l)
Med Rqmt Over N
e • • 0
• • • 0
• • • 0
• • • 0
• • • 0
0.0349 0.0200 0.0149 2
0.0352 0.0200 0.0152 2
0.0369 0.0200 0.0169 3
• • • 0
0.0400 0.0200 0.0200 3
• • • 0
• • • 0
• • • 0
• , • • 0
0.0100 0.0200 • 5
0.0160 0.0200 • 11
0.0100 0.0200 • 11
0.0120 0.0200 • 11
0.0065 0.0200 • 10
0.0150 0.0200 • 9
0.0120 0.0200 • 9
0.0070 0.0200 • 9
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a and 1993b.
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (m-1)
Med Rqmt Over N
« • t o
• • • 0
• • • 0
• • • 0
• • • 0
« • • 0
• • • 0
• • • 0
• • • 0
• • • 0
4.2 2.0 2.2 4
e » • 0
• • • 0
« • • 0
• • • .0
3.6 2.0 1.6 5
4.8 2.0 2.8 7
3.9 2.0 1.9 6
4.8 2.0 2.8 7
4.8 2.0 2.8 7
4.8 2.0 2.8 7
3.6 2.0 1.6 7
CBP Segmen
TSS (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
2.5 15 • 6
24.0 15 9.0 13
11.5 15 • 4
• • • 0
31.4 15 16.4 11
• « « 0
« • • 0
• • • 0
• • • 0
32.0 15 17.0 5
39.0 15 24.0 7
28.0 ' 15 13.0 7
25.5 15 10.5 7
20.0 15 5.0 7
26.0 15 11.0 7
17.5 15 2.5 7
t WT1 - Bush River (O
CHL a (ng/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • o
• • • o
8.3 15.0 • 6
34.5 15.0 19.5 14
22.5 15.0 7.5 3
• • « 0
18.0 15.0 3.0 10
« • • 0
• • • 0
• • • 0
• • • 0
38.2 15.0 23.2 5
6.5 15.0 • 7
21.7 15.0 6.7 7
68.5 15.0 53.5 7
45.5 15.0 30.5 7
50.3 15.0 35.3 7
28.9 15.0 13.9 7
ligohaline)
DIN (mg/l)
Med Rqmt Over N
« • • • 0
• • • 0
i • • 0
•. • • 0
• i • 0
• • • 0
1.5740 • • 6
0.0330 • • 14
1.9870 • • 3
• • • 0
2.4310 • • 1
• • o 0
• t • 0
• • • 0
• • • 0
0.4200 • • 5
0.1480 • • 7
0.2890 • • 7
0.0320 • • 7
0.3480 • • 7
0.5560 • • 7
0.6350 • • 7
DIP (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • » 0
• t • 0
0.0250 0.0200 0.0050 6
0.0300 0.0200 0.0100 14
0.0400 0.0200 0.0200 4
• • • 0
0.0800 0.0200 0.0600 1
« • « 0
• • • 0
• • • 0
• t • o
0.0100 0.0200 • 5
0.0060 0.0200 • 7
0.0040 0.0200 • 7
0.0040 0.0200 • 6
0.0040 0.0200 • 6
0.0040 0.0200 • 7
0.0040 0.0200 • 7
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a, 1993b.
-------
sAV Growing Season Water Quality median!* By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (m-1)
Med Rqmt Over N
• • • 0
• • • 0
t • • 0
• • t o
• • • 0
i • • 0
3.2 2.0 1.2 3
• • • 0
« • • o
e • • 0
3.3 2.0 1.3 6
• • • 0
• • • 0
• « • 0
• • • 0
1.1 2.0 • 2
4.8 2.0 2.8 7
3.3 2.0 1.3 6
3.6 2.0 1.6 7
3.6 2.0 1.6 7
3.6 2.0 1.6 7
3.6 2.0 1.6 7
CBP Segment W
TSS (mg/l)
Med Rqmt Over N
44.0 15 29.0 1
• • • 0
• • • 0
21.0 15 6.0 6
14.0 15 • 11
10.0 15 • 12
12.0 15 • 29
8.0 15 • 34
6.0 15 • 12
110.5 15 95.5 2
25.5 15 10.5 10
• • • 0
• • • 0
• • • 0
• • • 0
4.5 15 • 2
18.0 15 3.0 7
18.0 15 3.0 7
21.5 15 6.5 7
24.0 15 9.0 7
27.0 15 12.0 7
19.0 15 4.0 7
T2 - Gunpowder River
CHL a (^g/l)
Med Rqmt Over N
i > « o
• • • 0
• • • 0
50.0 15.0 35.0 3
16.5 15.0 1.5 11
7.5 15.0 • 11
10.4 15.0 • 30
4.3 15.0 • 32
15.5 15.0 0.5 12
... o
18.0 15.0 3.0 13
... o
... o
... o
... o
2.4 15.0 • 2
13.8 15.0 • 7
16.3 15.0 1.3 7
35.4 15.0 20.4 7
30.4 15.0 15.4 7
41.2 15.0 26.2 7
19.4 15.0 4.4 7
(Oligohaline)
DIN (mg/l)
Med Rqmt Over N
0.9500 • • 1
• • • 0
• • • 0
0.3690 o . 6
1.1780 • • 11
0.6430 • -12
0.6865 • • 30
1.2625 • • 34
1.5690 • • 9
1.5125 • • 2
1.8320 • • 1
• « • 0
« . . o
. . • 0
. « «o
0.4300 • • 2
0.0760 • • 7
0.1820 • • 7
0.0540 • • 7
0.3130 • • 7
0.5560 • • 7
0.5500 • • 7
DIP (mg/l)
Med Rqmt Over N
• < • o
t . • 0
• > • 0
0.0200 0.0200 • 6
0.0200 0.0200 • 11
0.0200 0.0200 • 12
0.0300 0.0200 0.0100 30
0.0200 0.0200 • 33
0.0400 0.0200 0.0200 12
0.0300 0.0200 0.0100 2
0.0100 0.0200 • 1
• • • 0
• • • 0
• • §0
• • • 0
0.0100 0.0200 • 2
0.0040 0.0200 • 7
0.0040 0.0200 • 7
0.0040 0.0200 • 6
0.0050 0.0200 • 6
0.0040 0.0200 • 7
0.0040 0.0200 • 7
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Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a and 1993b.
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (nrv1)
Med Rqmt Over N
• • • 0
• • • 0
• • « 0
• • • 0
• • • 0
• • « o
1.9 2.0 • 4
2.6 2.0 0.6 4
2.3 2.0 0.3 3
• • • 0
2.1 2.0 0.1 1
• • « 0
• • • 0
• • • 0
0.9 2.0 • 1
1.8 2.0 • 3
2.1 2.0 0.1 7
2.7 2.0 0.7 6
2.9 2.0 0.9 7
2.9 2.0 0.9 7
2.4 2.0 0.4 7
2.1 2.0 0.1 7
CBP Segment
TSS (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • o
• • • 0
17.0 15 2.0 3
10.0 15 • 3
6.0 15 • 4
23.5 15 8.5 4
14.0 15 • 3
... o
11.0 15 • 1
• • • 0
• • • 0
• • • 0
2.0 15 • 1
12.0 15 • 3
10.0 15 • 7
13.0 15 • 7
18.0 15 3.0 7
15.0 15 • 7
14.0 15 • 7
18.0 15 3.0 7
WT3 - Middle River (0
CHL a (ug/l)
Med Rqmt Over N
• • • 0
• • • 0
• « t o
• • • 0
45.0 15.0 30.0 3
15.0 15.0 • 3
10.4 15.0 • 4
41.0 15.0 26.0 4
13.2 15.0 • 3
• • • 0
10.6 15.0 • 1
• • « 0
• • • 0
• • • 0
8.3 15.0 • 1
25.6 15.0 10.6 3
19.7 15.0 4.7 7
17.3 15.0 2.3 7
28.2 15.0 13.2 7
31.4 15.0 16.4 7
18.9 15.0 3.9 7
19.2 15.0 4.2 6
bligohaline)
DIN (mg/l)
Med Rqmt Over N
• • « 0
• • • 0
• • «0
• • • 0
0.1300 • • 3
0.3970 • • 3
0.1740 • • 4
0.0390 • • 4
0.5105 • • 2
• • « 0
0.0550 • • 1
• • • 0
• • • 0
• • • 0
• • • 0
0.0400 • • 3
0.0400 • -7
0.1840 • • 7
0.1880 • • 7
0.1620 • • 7
0.2880 • • 7
0.0480 • • 7
DIP (mg/l)
Med Rqmt Over N
• • «0
• • » 0
• • • 0
• • • 0
0.0150 0.0200 • 2
0.0200 0.0200 • 3
0.0450 0.0200 0.0250 4
0.0300 0.0200 0.0100 4
0.0400 0.0200 0.0200 3
• • • 0
0.0100 0.0200 • 1
• • • 0
• • • 0
• • • 0
0.0100 0.0200 • 1
0.0100 0.0200 • 3
0.0040 0.0200 • 7
0.0040 0.0200 • 7
0.0040 0.0200 • 6
0.0070 0.0200 • 6
0.0040 0.0200 • 7
0.0040 0.0200 • 7
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a, 1993b.
-------
cp
ro
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (17V1)
Med Rqmt Over N
5.3 2.0 3.3 12
4.3 2.0 2.3 36
5.8 2.0 3.8 12
1.7 2.0 • 12
3.2 2.0 1.2 35
2.4 2.0 0.4 48
1.6 2.0 • 63
3.9 2.0 1.9 4
4.8 2.0 2.8 3
• • • 0
3.0 2.0 1.0 11
• • • 0
• • • o
• • • 0
• • • 0
4.8 2.0 2.8 7
4.8 2.0 2.8 7
4.8 2.0 2.8 7
3.6. 2.0 1.6 7
4.8 2.0 2.8 7
4.8 2.0 2.8 7
4.8 2.0 2.8 7
CBP Segm<
TSS (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
59.0 15 44.0 7
30.0 15 15.0 15
44.0 15 29.0 18
49.0 15 34.0 8
46.0 15 31.0 7
• • • 0
45.0 15 30.0 36
• • • 0
• • • 0
• • • 0
• • • 0
36.0 15 21.0 7
33.5 15 18.5 7
31.5 15 16.5 7
29.0 15 14.0 7
23.0 15 8.0 7
33.0 15 18.0 7
32.5 15 17.5 7
3nt WT4 - Back River
CHL a (ug/l)
Med Rqmt Over N
48.3 15.0 33.3 12
46.0 15.0 31.0 42
34.2 15.0 19.2 42
41.6 15.0 26.6 50
83.4 15.0 68.4 56
103.5 15.0 88.5 105
139.6 15.0 124.6 79
193.5 15.0 178.5 8
91.8 15.0 76.8 7
• • • 0
117.6 15.0 102.6 29
• • » 0
• • • 0
• • • 0
113.2 15!0 98.2 1
130.7 15.0 115.7 7
104.3 15.0 89.3 7
86.6 15.0 71.6 7
92.0 15.0 77.0 7
101.2 15.0 86.2 7
130.1 15.0 115.1 7
43.9 15.0 28.9 7
XDIigohaline)
DIN (mg/l)
Med Rqmt Over N
• • • 0
• • «0
• • • 0
• • • 0
2.8975 • • 24
5.2930 • • 75
1.7860 • • 19
1.7940 • • 8
5.5070 • • 5
• • • 0
6.2055 • • 54
• • • 0
• • « 0
• • • 0
• • • 0
3.0900 • • 7
2.4500 • • 7
3.3625 • • 6
4.0630 • • 6
2.4500 • • 5
2.2870 • • 6
2.0560 • • 7
DIP (mg/l)
Med Rqmt Over N
0.8450 0.0200 0.8250 18
0.9100 0.0200 0.8900 42
1.2300 0.0200 1.2100 36
1.1250 0.0200 1.1050 50
0.5900 0.0200 0.5700 77
1.2250 0.0200 1.2050 116
0.9000 0.0200 0.8800 70
0.2900 0.0200 0.2700 7
0.2000 0.0200 0.1800 7
• • • 0
0.9400 0.0200 0.9200 54
• • • 0
• • • 0
• • • 0
• • • 0
0.0200 0.0200 • 7
0.0070 0.0200 • 7
0.0300 0.0200 0.0100 7
0.0095 0.0200 • 6
0.0130 0.0200 • 6
0.0140 0.0200 • 7
0.0820 0.0200 0.0620 7
V)
CT
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (m-1)
Med Rqmt Over N
1.9 1.5 0,4 50
1.6 1.5 0.1 38
• • • 0
• • • 0
• • • o
« • • 0
1.4 1.5 • 3
1.5 1.5 • 1
1.6 1.5 0.1 6
2.0 1.5 0.5 6
1.6 1.5 0.1 26
• • • 0
• « ' • 0
« • • 0
1.5 1.5 • 3
2.2 1.5 0.7 6
1.8 1.5 0.3 13
1.8 1.5 0.3 14
2.1 1.5 0.6 13
1.6 1.5 0.1 14
2.1 1.5 0.6 13
2.1 1.5 0.6 14
CBP Segment V
TSS (mg/l)
Med Rqmt Over N
• • • 0
• • • o
• • • 0
• • • o
28.0 15 13.0 24
20.0 15 5.0 19
17.0 15 2.0 27
23.0 15 8.0 20
12.0 15 • 15
17.5 15 2.5 14
11.7 15 • 69
12.0 15 • 1
• • • 0
• • • 0
6.0 15 • 7
8.0 15 • 13
17.5 15 2.5 14
11.5 15 • 14
11.5 15 • 14
9.5 15 • 14
18.0 15 3.0 14
13.0 15 • 13
VT5 - Patapsco River i
CHL a (ng/l)
Med Rqmt Over N
42.0 15.0 27.0 46
38.0 15.0 23.0 42
« • • 0
« • • 0
60.0 15.0 45.6 13
29.3 15.0 14.3 10
12.8 15.0 • 14
20.3 15.0 5.3 16
11.4 15.0 • 15
24.6 . 15.0 9.6 11
23.0 15.0 8.0 47
• • • 0
• • • 0
• • • o
23.3 15.0 8.3 6
26.2 15.0 11.2 13
34.8 15.0 19.8 14
32.2 15.0 17.2 14
29.7 15.0 14.7 14
23.6 15.0 8.6 13
33.4 15.0 18.4 12
26.1 15.0 11.1 10
Mesohaline)
DIN (mg/l)
Med Rqmt Over N
1.0420 0.1500 0.8920 64
1.0400 0.1500 0.8900 46
• • • 0
• • • 0
0.9530 0.1500 0.8030 13
1.0980 0.1500 0.9480 10
1.2990 0.1500 1.1490 14
0.8715 0.1500 0.7215 16
1.0470 0.1500 0.8970 13
1.2380 0.1500 1.0880 12
1.3270 0.1500 1.1770 11
• • • 0
i t • 0
• « • 0
0.9300 0.1500 0.7800 7
0.5700 0.1500 0.4200 13
0.4000 0.1500 0.2500 13
0.7920 0.1500 0.6420 13
0.6530 0.1500 0.5030 14
0.8340 0.1500 0.6840 14
0.5710 0.1500 0.4210 14
0.3440 0.1500 0.1940 12
DIP (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • «0
• • • 0
0.0400 0.0100 0.0300 13
0.0400 0.0100 0.0300 10
0.0400 0.0100 0.0300 13
0.0300 0.0100 0.0200 16
0.0500 0.0100 0.0400 15
0.0250 0.0100 0.0150 12
0.0400 0.0100 0.0300 11
• • • 0
• • • 0
• ^ • • 0
0.0200 0.0100 0.0100 7
0.0200 0.0100 0.0100 13
0.0200 0.0100 0.0100 13
0.0160 0.0100 0.0060 14
0.0070 0.0100 • 14
0.0090 0.0100 • 14
0.0060 0.0100 • 13
0.0050 0.0100 • 12
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a, 1993b.
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (m-1)
Med Rqmt Over N
• • • 0
• • • . 0
• • « o
• • • 0
• • • o
• • • 0
1.6 1.5 0.1 3
1.9 1.5 0.4 46
1.6 1.5 0.1 3
• • « 0
2.4 1.5 0.9 2
• • • 0
• • • 0
• • • o
• • • 0
1.5 1.5 • 6
1.6 1.5 '0.1 7
1.5 1.5 • 7
1.3 1.5 • 7
1.8 1.5 0.3 7
2.1 1.5 0.6 7
2.1 1.5 0.6 7
CBP Segment \
TSS (mg/l)
Med Rqmt Over N
• • • 0
• « • 0
• • • 0
• • • 0
11.0 15 • 3
22.0 15 7.0 3
9.0 15 • 4
12.0 15 • 65
23.0 15 8.0 3
• • • 0
11.0 15 • 1
... o
... o
• • • 0
... o
5.0 15 • 6
8.0 15 • 7
5.0 15 • 7
9.0 15 • 7
18.0 15 3.0 7
13.0 15 • 7
11.0 15 • 7
/VT6 - Magothy River (
CHL a (ug/1)
Med Rqmt Over N
« • • 0
... o
« • • 0
... o
21.0 15.0 6.0 3
42.0 15.0 27.0 55
25.5 15.0 10.5 25
36.8 15.0 21.8 84
7.5 15.0 • 3
• • • 0
84.9 15.0 69.9 1
• « • 0
• • • 0
... o
... o
14.2 15.0 • 6
17.2 15.0 2.2 7
14.8 15.0 • 7
16.4 15.0 1.4 7
45.7 15.0 30.7 6
12.6 15.0 • 7
16.4 15.0 1.4 5
Mesohaline)
DIN (mg/l)
Med Rqmt Over N
« • • 0
• > • 0
. . • o
• « • 0
0.2980 0.1500 0.1480 3
0.1140 0.1500 • 55
0.4470 0.1500 0.2970 25
0.1125 0.1500 • 84
0.5690 0.1500 0.4190 2
. • • 0
0.0730 0.1500 • 1
• « • 0
. . • 0
• . • o
« « • 0
0.0625 0.1500 • 6
0.0540 0.1500 • 7
0.0560 0.1500 • 7
0.3500 0.1500 0.2000 7
0.1760 0.1500 0.0260 7
0.1540 0.1500 0.0040 7
0.0720 0.1500 • 7
DIP (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• . • • 0
• • • 0
0.0100 0.0100 • 3
0.0400 0.0100 0.0300 55
0.0200 0.0100 0.0100 25
0.0300 0.0100 0.0200 82
0.0400 0.0100 0.0300 3
• • • 0
0.0400 0.0100 0.0300 1
• • • 0
• « • 0
• • • 0
• « « 0
0.0200 0.0100 0.0100 6
0.0060 0.0100 • 7
0.0040 0.0100 • 7
0.0040 0.0100 • 7
0.0040 0.0100 • 7
0.0040 0.0100 • 7
0.0040 0.0100 • 7
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a and I993b.
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (m-1)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
... 0
• • • 0
1.6 1.5 0.1 8
• • • 0
• • • 0
« • • 0
• • • 0
• • • 0
« • • 0
• • • o
1.6 1.5 0.1 3
1.6 1.5 0.1 7
1.5 1.5 • 7
1.0 1.5 • 7
1.5 1.5 • 8
2.1 1.5 0.6 7
1.8 1.5 0.3 7
CBP Segment
TSS (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • » 0
• • • 0
21.0 15 6.0 6
6.0 15 • 3
8.5 15 . 6
11.0 15 • 5
9.0 15 • 3
• • • 0
« • • 0
• • • 0
i • i o
• • • 0
• • • 0
9.0 15 • 3
7.0 15 • 7
9.0 '15 • 7
6.0 15 • 7
16.5 15 1.5 8
17.0 15 2.0 7
10.0 15 • 7
WT7 - Severn River (l^
CHL a (ug/l)
Med Rqmt Over N
26.5 15.0 11.5 14
25.0 15.0 10.0 19
46.5 15.0 31.5 4
« • • 0
33.0 15.0 18.0 5
16.5 15.0 1.5 3
20.8 15.0 5.8 6
31.5 15.0 16.5 16
10.8 15.0 • 4
• • • 0
• • • 0
... o
... o
... o
... o
25.4 15.0 10.4 3
• 14.7 15.0 • 7
26.1 15.0 11.1 6
15.1 15.0 0.1 7
36.0 15.0 21.0 7
25.5 15.0 10.5 6
14.3 15.0 • 4
i/lesohaline)
DIN (mg/l)
Med Rqmt Over N
< > » 0
. > • 0
. . • 0
. . • 0
0.1870 0.1500 0.0370 6
0.3430 0.1500 0.1930 3
0.2080 0.1500 0.0580 6
0.0420 0.1500 • 16
0.7990 0.1500 0.6490 3
. > « 0
. . • o
. . • 0
• • • • 0
. . • 0
• • « 0
0.0500 0.1500 • 3
0.0940 0.1500 • 7
0.0600 0.1500 • 7
0.1300 0.1500 • 7
0.2380 0.1500 0.0880 8
0.0560 0.1500 • 7
0.0640 0.1500 • 7
DIP (mg/l)
Med Rqmt Over N
• • « 0
• « • 0
0.0200 0.0100 0.0100 4
• • • 0
0.0250 0.0100 0.0150 6
0.0200 0.0100 0.0100 3
0.0250 0.0100 0.0150 6
0.0300 0.0100 0.0200 15
0.0300 0.0100 0.0200 4
• • • 0
• « • 0
. . • 0
• « «0
. . • 0
• « « 0
0.0200 0.0100 0.0100 3
0.0100 0.0100 • 7
0.0100 0.0100 • 7
0.0080 0.0100 • 7
0.0060 0.0100 • 8
0.0060 0.0100 • 7
0.0100 0.0100 • 7
en
c
cr
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (m-1)
Med Rqmt Over N
1.6 1.5 0.1 1
• • • 0
• • • 0
• « • 0
• • • 0
• • • o
1.5 1.5 • 5
1.7 1.5 0.2 52
1.6 1.5 0.1 4
• • • 0
2.3 1.5 0.8 2
• • • 0
• • • 0
• • • 0
1.9 1.5 0.4 3
1.9 1.5 0.4 18
2.1 1.5 0.6 21
1.8 1.5 0.3 20
2.1. 1.5 0.6 21
2.1 1.5 0.6 24
2.4 1.5 0.9 21
2.1 1.5 0.6 25
CBP Segment WT8 -
TSS (mg/l)
Med Rqmt Over N
20.0 15 5.0 1
• • • 0
• • • 0
• • • 0
13.5 15 • 8
16.0 15 1.0 9
16.0 15 1.0 14
12.0 15 • 11
12.0 15 • 11
• • • 0
12.5 15 • 2
• • • 0
• • • 0
• • • 0
13.0 15 • 3
10.5 15 • 18
14.0 15 • 21
14.0 15 • 21
14.0 15 • 21
19.0 15 4.0 24
20.0 15 5.0 21
18.0 15 3.0 25
South/Rhode/West Ri
CHL a (ug/l)
Med Rqmt Over N
39.0 15.0 24.0 29
36.0 15.0 21.0 35
82.8 15.0 67.8 8
• • • 0
39.8 15.0 24.8 8
15.0 15.0 • 9
40.8 15.0 25.8 15
22.5 15.0 7.5 65
14.1 15.0 • 11
• • • 0
11.9 15.0 • 2
• • t o
• • • 0
• • • 0
10.1 15.0 • 3
15.2 15.0 0.2 18
16.6 15.0 1.6 20
17.3 15.0 2.3 20
26.6 15.0 11.6 21
39.9 15.0 24.9 16
22.7 15.0 7.7 21
20.8 15.0 5.8 20
vers (Mesohaline)
DIN (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• « • 0
• • • 0
0.0900 0.1500 • 8
0.1670 0.1500 0.0170 9
0.1660 0.1500 0.0160 15
0.0420 0.1500 • 65
0.3810 0.1500 0.2310 9
• « «0
0.0485 0.1500 • 2
• • • 0
• • • 0
• • • 0
0.1850 0.1500 0.0350 3
0.0500 0.1500 -18
0.0420 0.1500 • 21
0.0460 0.1500 • 21
0.0400 0.1500 -21
0.0430 0.1500 • 24
0.0520 0.1500 • 21
0.0600 0.1500 • 25
DIP (mg/l)
Med Rqmt Over N
0.0400 0.0100 0.0300 1
t • • 0
0.0300 0.0100 0.0200 8
• • • 0
0.0400 0.0100 0.0300 8
0.0400 0.0100 0.0300 9
0.0300 0.0100 0.0200 14
0.0683 0.0100 0.0583 64
0.0400 0.0100 0.0300 11
• • • 0 .
0.0300 0.0100 0.0200 2
• • • 0
• • • 0
• • • 0
0.0200 0.0100 0.0100 3
0.0200 0.0100 0.0100 18
0.0100 0.0100 •' 21
0.0120 0.0100 0.0020 21
0.0080 0.0100 • 21
0.0070 0.0100 • 24
0.0040 0.0100 • 21
0.0060 0.0100 • 25
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a and 1993b.
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (m-1)
Med Rqmt Over N
4.3 2.0 2.3 1
• • • 0
• • • 0
• • • 0
• « • 0
• • • 0
• • • 0
2.9 2.0 0.9 40
3.2 2.0 1.2 105
• • • o
12.5 2.0 10.5 48
• « • 0
• • • 0
• • • 0
• • « 0
4.8 2.0 2.8 49
4.8 2.0 2.8 66
3.6 2.0 1.6 56
3.6 2.0 1.6 55
4.8 2.0 2.8 49
3.6 2.0 1.6 56
3.6 2.0 1.6 56
CBP Segment TF1
TSS (mg/l)
Med Rqmt Over N
69.8 15 54.8 7
43.6 15 28.6 1
47.4 15 32.4 2
• • • 0
41.0 15 26.0 26
29.0 15 14.0 14
17.0 15 2.0 20
32.3 15 17.3 16
26.0 15 11.0 241
34.0 15 19.0 7
32.5 15 17.5 70
• • • 0
• • • 0
• • • 0
• • • 0
23.0 15 8.0 93
26.0 15 11.0 121
23.5 15 8.5 102
24.0 15 9.0 84
20.0 15 5.0 76
24.9 15 9.9 84
19.4 15 4.4 84
- Upper Patuxent Riv
CHL a (jig/l)
Med Rqmt Over N
40.1 15.0 25.1 10
• • • 0
• • • 0
• • • 0
28.5 15.0 13.5 26
22.8 15.0 7.8 14
5.4 15.0 • 21
27.4 15.0 12.4 36
17.6 15.0 2.6 142
12.0 15.0 • 6
29.2 15.0 14.2 77
• • • 0
• • • 0
• • • 0
• • • 0
11.7 15.0 • 76
13.0 15.0 • 121
7.2 15.0 • 98
12.6 15.0 • 81
6.1 15.0 • 59
11.6 15.0 • 72
15.7 15.0 0.7 80
er (Oligohaline)
DIN (mg/l)
Med Rqmt Over N
37.6875 • -11
52.4857 • • 1
• • • 0
• • • 0
1.1455 • • 26
1.2070 • • 14
2.0200 • • 21
1.7010 • • 36
1.6075 • • 238
2.2730 • • 7
1.3245 • • 62
• • • 0
• • • 0
• « • 0
• • • 0
0.9200 • • 93
0.9700 • -120
1.0240 • • 98
0.7230 • • 78
1.0160 • • 75
0.8670 • • 84
0.3975 • • 84
DIP (mg/l)
Med Rqmt Over N
2.0875 0.0200 2.0675 13
2.2143 0.0200 2.1943 1
0.1995 0.0200 0.1795 2
• • • 0
0.1950 0.0200 0.1750 26
0.1050 0.0200 0.0850 14
0.2700 0.0200 0.2500 21
0.2950 0.0200 0.2750 36
0.1200 0.0200 0.1000 240
0.3000 0.0200 0.2800 7
0.0750 0.0200 0.0550 62
• • • 0
• • «0
• • • 0
• • « 0
0.0500 0.0200 0.0300 91
0.0520 0.0200 0.0320 122
0.0500 0.0200 0.0300 93
0.0370 0.0200 0.0170 84
0.0370 0.0200 0.0170 76
0.0314 0.0200 0.0114 82
0.0353 0.0200 0.0153 84
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a, 1993b.
-------
SAV Growing Season Water Duality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (m-1)
Med Rqmt Over N
2.9 1.5 1.4 1
• • • 0
• • • 0
• • • o
• • • 0
• • • 0
• • • 0
2.3 1.5 0.8 9
2.6 1.5 1.1 23
• • • 0
7.7 1.5 6.2 9
• • • 0
• • • 0
• « • 0
• • • 0
2.9 1.5 1.4 14
2.9 1.5 1.4 17
2.2 1.5 0.7 14
2.2 1.5 0.7 14
2.9 1.5 1.4 13
2.4 1.5 0.9 14
2.9 1.5 1.4 14
CBP Segment RET
TSS (mg/l)
Med Rqmt Over N
• « « 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • o
25.0 15 10.0 32
• • • 0
22.5 15 7.5 11
• • • 0
• • • 0
• • • 0
• • • 0
24.0 15 9.0 14
19.0 15 4.0 17
14.0 15 • 14
16.0 15 1.0 14
21.0 15 6.0 13
19.7 15 4.7 14
18.7 15 3.7 14
I - Middle Patuxent Rh
CHL a (ng/l)
Med Rqmt Over N
32.3 15.0 17.3 6
• • « 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
45.0 15.0 30.0 3
21.3 15.0 6.3 15
• • • 0
16.6 15.0 1.6 12
• • • 0
• • • 0
• • • 0
• • • 0
14.0 15.0 • 12
10.5 15.0 • 17
12.3 15.0 • 14
10.0 15.0 • 14
11.2 15.0 • 13
17.3 15.0 2.3 14
17.0 15.0 2.0 14
/er (Mesohaline)
DIN (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • « 0
• • • 0
• • • 0
• • • 0
• t • 0
0.0380 0.1500 • 3
0.2200 0.1500 0.0700 31
• • • 0
0.0527 0.1500 • 7
• • • 0
• • • 0
• • • 0
• • • 0
0.0800 0.1500 • 13
0.1340 0.1500 • 17
0.2040 0.1500 0.0540 14
0.3000 0.1500 0.1500 13
0.3800 0.1500 0.2300 13
0.1560 0.1500 0.0060 14
0.0692 0.1500 • 14
DIP (mg/l)
Med Rqmt Over N
0.1360 0.0100 0.1260 6
• • • 0
0.0484 0.0100 0.0384 2
• • • 0
• • • 0
• • • 0
• • • 0
0.0500 0.0100 0.0400 3
0.0500 0.0100 0.0400 33
• • • 0
0.0567 0.0100 0.0467 7
• « • 0
• • • 0
• • • 0
• « • 0
0.0450 0.0100 0.0350 14
0.0820 0.0100 0.0720 17
0.0480 0.0100 0.0380 13
0.0430 0.0100 0.0330 14
0.0340 0.0100 0.0240 13
0.0436 0.0100 0.0336 14
0.0442 0.0100 0.0342 14
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a and 1993b.
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (m-1)
Med Rqmt Over N
• « • 0
• « • 0
• • • 0
• • • 0
« • • 0
• • • 0
• • • 0
0.9 1.5 • 3
1.2 1.5 • 13
• • • 0
3.9 1.5 2.4 21
• • • 0
• • • 0
• • t o
• • • o
1.2 1.5 • 56
1.2 1.5 • 67
1.0 1.5 • 55
1.0 1.5 • 57
1.1 1.5 • 52
1.4 1.5 • 56
1.1 1.5 • 56
CBP Segment LE1
TSS (mg/l)
Med Rqmt Over N
38.0 15 23.0 6
18.0 15 3.0 1
17.4 15 2.4 2
• • • 0
10.0 15 • 2
24.0 15 9.0 3
• • • 0
64.0 15 49.0 1
18.0 15 3.0 11
• • • 0
19.3 15 4.3 53
• t • o
• t • o
• • • 0
• • • 0
9.0 15 • 56
7.5 15 • 68
6.0 15 • 56
10.5 15 • 57
16.0 15 1.0 52
9.9 15 • 56
6.5 15 • 56
- Lower Patuxent Riv
CHL a (\ig/\)
Med Rqmt Over N
45.0 15.0 30.0 5
• • • 0
• • • 0
• • • 0
36.0 15.0 21.0 2
11.3 15.0 • 3
• • • 0
13.5 15.0 • 1
13.3 15.0 • 8
• • • 0
12.5 15.0 • 29
• • • 0
• • .« 0
• • • 0
• • • 0
5.2 15.0 • 46
9.1 15.0 • 68
10.5 15.0 • 56
9.9 15.0 • 56
14.3 15.0 • 50
11.7 15.0 • 53
7.7 15.0 • 55
er (Mesohaline)
DIN (mg/l)
Med Rqmt Over N
4.2000 0.1500 4.0500 6
1.7000 0.1500 1.5500 1
• • • 0
• • • 0
0.2805 0.1500 0.1305 2
0.4150 0.1500 0.2650 3
• • • 0
0.0950 0.1500 • 1
0.1580 0.1500 0.0080 11
t i • 0
0.0530 0.1500 • 39
• • • 0
• • • 0
• • • 0
• • • 0
0.1000 0.1500 • 56
0.0920 0.1500 • 68
0.1210 0.1500 • 56
0.1640 0.1500 0.0140 53
0.1730 0.1500 0.0230 52
0.0893 0.1500 • 56
0.0918 0.1500 • 56
DIP (mg/l)
Med Rqmt Over N
0.2270 0.0100 0.2170 11
0.2000 0.0100 0.1900 1
0.0264 0.0100 0.0164 2
0.3000 0.0100 0.2900 1
0.0150 0.0100 0.0050 2
0.0600 0.0100 0.0500 3
• • • 0
0.0100 0.0100 • 1
0.0400 0.0100 0.0300 11
« • • o
0.0147 0.0100 0.0047 40
• • • 0
• • • 0
• • • 0
• • • 0
0.0100 0.0100 • 56
0.0125 0.0100 0.0025 68
0.0140 0.0100 0.0040 52
0.0120 0.0100 0.0020 57
0.0080 0.0100 • 52
0.0056 0.0100 • 56
0.0077 0.0100 • 56
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a, 1993b.
x'
00
-------
roi
SAV Crnwina Spa«nn Wafer nnnlitv Medians Bv se°!™e™t 1970 to 1991)
fy ~" ~ ""•" " * ~~ ~* ~^C. ~*~" *"mJ ~~ ~* ™r •—— ~^i~—•-" J **-* **^5""* '*"' \ /
l>
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (m-1)
Med Rqmt Over N
c
• • • 0
• • • 0
• • • 0
• • • 0
2.4 2.0 0.4 21
2.4 2.0 0.4 33
2.5 2.0 0.5 34
2.6 2.0 0.6 40
1.1 2.0 • 344
2.4 2.0 0.4 21
• • • 0
• • • 0
• • • 0
1.9 2.0 • 3
• • • 0
2.4 2.0 0.4 53
2.1 2.0 0.1 56
2.1 2.0 0.1 64
2.4 2.0 0.4 55
2.4 2.0 0.4 55
1.9 2.0 • 56
CBP Segment TF2
TSS (mg/l)
Med Rqmt Over N
» . - «
y
• • • 0
• • • 0
• « • 0
24.0 15 9.0 55
18.0 15 3.0 31
20.0 15 5.0 23
14.0 15 • 53
23.0 15 8.0 64
18.0 15 3.0 57
14.0 15 • 53
• • • 0
• • • 0
• • • 0
• • • o
• • • 0
15.6 15 0.6 53
14.0 15 • 56
17.6 15 2.6 64
13.5 15 • 56
18.0 15 3.0 56
11.0 15 • 56
- Upper Potomac Riv<
CHL a (ug/l)
Med Rqmt Over N
A^ i~ 4 t- f\ *»*» r » *•
j/.j u.v/ Of..j ty
100.0 15.0 85.0 12
o • • 0
• • • 0
30.0 15.0 15.0 58
23.0 15.0 8.0 49
55.5 15.0 40.5 61
34.0 15.0 19.0 53
31.9 15.0 16.9 60
24.5 15.0 9.5 296
32.7 15.0 17.7 45
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
9.9 15.0 • 53
7.8 15.0 • 55
7.9 15.0 • 61
6.9 15.0 • 50
5.4 15.0 • 56
8.0 15.0 • 53
9r (Tidal Fresh)
DIN (mg/l)
Med Rqmt Over N
1.1 700 • '45
• • • 0
• • • 0
• • • 0
0.2885 • • 58
1.4700 - • -52
1.0330 • • 61
1.0350 • • 59
0.8770 • • 55
1.4255 • • 240
1.0900 • • 53
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
1.6700 • • 53
1.7700 • • 56
1.8440 • -55
1.9820 • • 56
2.0220 • • 56
2.0380 • • 52
DIP (mg/l)
Med Rqmt Over N
• • • o
0.2050 0.0200 0.1850 2
• • '0
• • • 0
0.0500 0.0200 0.0300 58
0.0800 0.0200 0.0600 51
0.0600 0.0200 0.0400 61
0.0400 0.0200 0.0200 59
0.0600 0.0200 0.0400 65
0.0500 0.0200 0.0300 329
0.0300 0.0200 0.0100 53
• • • 0
• • • • 0
• • • 0
• • « 0
• • • 0
0.0240 0.0200 0.0040 53
0.0300 0.0200 0.0100 56
0.0240 0.0200 0.0040 62
0.0320 0.0200 0.0120 56
0.0300 0.0200 0.0100 51
0.0160 0.0200 • 56
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a and 1993b.
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (rrv1)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • o
• • • 0
2.4 2.0 0.4 17
2.2 2.0 0.2 32
2.8 2.0 0.8 19
2.6 2.0 0.6 28
1.0 2.0 • 124
2.3 2.0 0.3 26
• • • 0
• . • • 0
• • • 0
2.8 2.0 0.8 4
• • t o
2.1 2.0 0.1 56
2.1 2.0 0.1 56
1.9 2.0 • 60
2.4 2.0 0.4 55
2.9 2.0 0.9 53
1.8 2.0 • 42
CBP Segment RET
TSS (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
18.0 15 3.0 54
10.0 15- • 17
12.0 15 • 12
23.0 15 8.0 22
17.0 15 2.0 30
17.3 15 2.3 34
14.0 15 • 68
• • • 0
• « • 0
« • • 0
• • • 0
• • • 0
13.6 15 • 56
12.5 "15 • 56
13.0 15 • 60
14.5 15 • 56
20.0 15 5.0 53
12.5 15 • 42
2 - Middle Potomac Ri
CHL a (ng/l)
Med Rqmt Over N
• • • 0
40.0 15.0 25.0 7
• • • 0
• • • o
24.0 15.0 9.0 58
12.0 15.0 • 34
10.5 15.0 • 46
33.0 15.0 18.0 23
20.4 15.0 5.4 31
22.5 15.0 7.5 97
35.4 15.0 20.4 24
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
4.3 15.0 • 56
5.1 15.0 • 54
4.5 15.0 • 55
4.5 15.0 • 53
3.4 15.0 • 50
6.8 15.0 • 37
ver (Oligohaline)
DIN (mg/l)
Med Rqmt Over N
• • • 0
0.2215 • • 7
0.7435 • • 7
• • • 0
0.3805 • • 58
0.8800 • • 33
0.5075 • • 46
0.3260 • • 27
0.6980 • • 27
0.8460 • • 55
0.4350 • • 67
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
0.5830 • • 56
0.8720 • • 56
0.7120 • • 60
1.5120 • • 50
1.3160 • • 53
0.5210 • • 38
DIP (mg/l)
Med Rqmt Over N
0.3315 0.0200 0.3115 7
0.2700 0.0200 0.2500 14
0.2200 0.0200 0.2000 7
• • • 0
0.0500 0.0200 0.0300 58
0.0700 0.0200 0.0500 35
0.0600 0.0200 0.0400 46
0.0800 0.0200 0.0600 27
0.0900 0.0200 0.0700 31
0.0494 0.0200 0.0294 114
0.0420 0.0200 0.0220 68
• • • 0
t • • 0
• • • 0
• • • 0
• • • 0
0.0600 0.0200 0.0400 56
0.0485 0.0200 0.0285 56
0.0530 0.0200 0.0330 60
0.0500 0.0200 0.0300 56
0.0480 0.0200 0.0280 50
0.0300 0.0200 0.0100 42
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a, 1993b.
Q.
X"
CD
-------
roi
oruvnng oeason vvaicr
Meuians By Segment
4. . 4 *\t\-t \
tu Lyyi)
l>
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (rrr1)
Med Rqmt Over N
« • • 0
• • • 0
• • • 0
• • • 0
• • • 0
» • • 0
• • • o
• • • 0
• • • 0
1.5 1.5 • 1
0.9 1.5 • 8
• • • 0
• • • 0
• • • 0
0.7 1.5 • 8
0.9 1.5 • 18
0.9 1.5 • 26
1.0 1.5 • 27
1.0 1.5 • 27
1.0 1.5 • 28
1.2 1.5 • 27
0.9 1.5 • 28
CBP Segment LE2
TSS (mg/l)
Med Rqmt Over N
20.0 15 5.0 1
... 0
• « • 0
• « • 0
16.0 15 1.0 37
8.0 15 • 25
6.0 15 • 24
11.0 15 • 27
18.0 15 3.0 16
24.0 15 9.0 3
5.9 15 • 60
t • • o
• • » 0
• • • 0
4.0 15 • 10
7.0 15 • 25
5.0 15 • 27
4.4 15 • 28
8.0 15 • 26
6.9 15 • 28
7.4 15 • 26
5.7 15 • 28
- Lower Potomac Riv
CHL a (ug/l)
Med Rqmt Over N
t • • 0
• • • 0
• • • o
• • • 0
16.5 15.0 1.5 37
15.0 15.0 • 28
5.3 15.0 • 24
6.8 15.0 • 28
13.1 15.0 • 16
17.6 15.0 2.6 71
7.0 15.0 • 7
• • • 0
• • • 0
• • • 0
9.0 15.0 • 9
7.7 15.0 • 24
7.6 15.0 • 27
13.7 15.0 • 27
14.2 15.0 • 26
15.0 15.0 • 22
10.2 15.0 • 24
7.2 15.0 • 25
er (Mesohaline)
DIN (mg/l)
Med Rqmt Over N
3.5000 0.1500 3.3500 1
0.4190 0.1500 0.2690 7
0.5660 0.1500 0.4160 7
• • • 0
0.1260 0.1500 • 37
0.3660 0.1500 0.2160 25
0.1720 0.1500 0.0220 24
0.1597 0.1500 0.0097 27
0.2890 0.1500 0.1390 13
0.4050 0.1500 0.2550 5
0.0579 0.1500 • 46
• • • 0
• • • 0
• • • 0
0.0690 0.1500 • 11
0.0794 0.1500 • 24
0.0974 0.1500 • 27
0.0670 0.1500 • 28
0.0520 0.1500 • 27
0.1240 0.1500 • 27
0.0870 0.1500 • 27
0.0600 0.1500 • 27
DIP (mg/l)
Med Rqmt Over N
0.2800 0.0100 0.2700 7
0.1800 0.0100 0.1700 7
0.1200 0.0100 0.1100 7
• • • 0
0.0400 0.0100 0.0300 37
0.0500 0.0100 0.0400 28
0.0400 0.0100 0.0300 24
0.0400 0.0100 0.0300 27
0.0600 0.0100 0.0500 17
0.0173 0.0100 0.0073 56
0.0130 0.0100 0.0030 47
• • • 0
• • • 0
• • • 0
0.0070 0.0100 • 11
0.0095 0.0100 • 23
0.0060 0.0100 • 27
0.0048 0.0100 • 28
0.0043 0.0100 • 27
0.0060 0.0100 • 28
0.0046 0.0100 • 26
0.0040 0.0100 • 28
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a and 1993b.
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971-
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (m 1)
Med Rqmt Over N
• • • 0
t • « 0
• • • 0
• • • 0
• • • o
2.4 2.0 0.4 46
2.9 2.0 0.9 157
2.9 2.0 0.9 155
3.6 2.0 1.6 70
2.4 2.0 0.4 50
3.3 2.0 1.3 2
• • • 0
• « t o
• • • 0
2.4 2.0 0.4 9
2.4 2.0 0.4 14
2.7 2.0 0.7 12
3.6 2.0 1.6 12
2.9 2.0 0.9 35
3.6 2.0 1.6 46
3.6 2.0 1.6 44
2.9 2.0 0.9 49
CBP Segment TF3 -
TSS (mg/l)
Med Rqmt Over N
• • • 0
• • t o
• • • 0
• • • 0
• • • 0
• • • 0
• • • o
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
t • • 0
• • • " 0
• • • 0
• • • 0
• • • o
• • • 0
17.5 15 2.5 32
25.0 15 10.0 47
22.5 15 7.5 46
23.0 15 8.0 50
Jpper Rappahannock
CHL a (ug/l)
Med Rqmt Over N
• • « 0
• • • • 0
• • • 0
• • « 0
• • • 0
4.5 15.0 • 22
1.8 15.0 • 82
8.0 15.0 • 205
3.2 15.0 • 109
1.5 15.0 - 50
« • • 0
• • • o
• • • o
« • • 0
• • • 0
21.2 15.0 6.2 18
11.3 15.0 • 27
6.8 15.0 • 24
11.9 15.0 • 33
7.7 15.0 • 49
8.9 15.0 • 45
12.7 15.0 • 40
River (Oligohaline)
DIN (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • «0
• • • 0
• • • 0
0.5615 • • 74
0.6159 • • 61
0.4125 • • 44
0.5529 • • 51
0.5900 • • 23
• t • 0
• • « 0
• • • 0
• • «0
0.2900 • • 12
0.1900 • • 27
0.1100 • • 27
0.4600 • • 23
0.2850 • • 36
0.6250 • • 48
0.6000 • • 45
0.2500 • • 49
DIP (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
0.0127 0.0200 • 74
0.0310 0.0200 0.0110 80
0.0273 0.0200 0.0073 69
0.0370 0.0200 0.0170 80
0.0201 0.0200 0.0001 68
• • • 0
• • • 0
• • • 0
• • • 0
0.0100 0.0200 • 12
0.0100 0.0200 • 27
0.0100 0.0200 • 22
0.0100 0.0200 • 24
0.0100 0.0200 • 36
0.0100 0.0200 • 48
0.0100 0.0200 • 45
0.0100 0.0200 • 49
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a, 1993b.
-------
O A17 t~1 • C< ««7_.i *~\—
&f\v vjiuvring ocasun vyaici • •••
fvleuiaiis By Segment (I97G io
Year
19/0
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (nr1)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • o
• • • 0
2.7 1.5 1.2 8
2.9 1.5 1.4 31
2.9 1.5 1.4 23
4.8 1.5 3.3 19
3.6 1.5 2.1 19
2.9 1.5 1.4 4
• • • 0
• • • 0
• • • o
2.1 1.5 0.6 12
2.0 1.5 0.5 28
2.9 1.5 1.4 26
2.9 1.5 1.4 26
2.5 1.5 1.0 26
3.2 1.5 1.7 25
3.2 1.5 1.7 27
2.9 1.5 1.4 27
CBP Segment RET3 -
TSS (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• « « 0
• • • 0
• • • o
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • « 0
• • • 0
13.0 15 • 4
35.0 15 20.0 8
29.0 15 14.0 6
42.5 15 27.5 2
29.5 15 14.5 20
28.0 15 13.0 28
38.0 15 23.0 26
22.5 15 7.5 28
Middle Rappahannock
CHL a (ug/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
4.0 15.0 • 4
2.6 15.0 • 17
7.2 15.0 • 24
6.7 15.0 • 24
4.8 15.0 • 8
• • • 0
• • • 0
• • • 0
• • • o
» • • 0
10.3 15.0 • 18
10.6 15.0 • 28
11.5 15.0 • 26
7.6 15.0 • 25
16.4 15.0 1.4 28
8.3 15.0 • 28
12.0 15.0 • 28
River (Mesohaline)
DIN (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
0.4870 0.1500 0.3370 13
0.2135 0.1500 0.0635 12
0.5314 0.1500 0.3814 5
0.1414 0.1500 • 14
0.5600 0.1500 0.4100 4
« • • 0
• • • 0
• • • 0
• • • 0
0.1500 0.1500 • 13
0.1000 0.1500 • 28
0.1000 0.1500 • 26
0.2450 0.1500 0.0950 16
0.1000 0.1500 • 23
0.1300 0.1500 • 28
0.1050 0.1500 • 26
0.1300 0.1500 • 28
DIP (mg/l)
Med Rqmt Over N
• « • 0
• t • 0
• • «0
• • • 0
• • « 0
0.0152 0.0100 0.0052 13
0.0223 0.0100 0.0123 16
0.0174 0.0100 0.0074 22
0.0170 0.0100 0.0070 21
0.0211 0.0100 0.0111 11
• • • 0
« • • 0
• • « 0
• » • 0
0.0100 0.0100 • 14
0.0100 0.0100 • 28
0.0100 0.0100 • 22
0.0100 0.0100 • 26
0.0100 0.0100 • 26
0.0100 0.0100 • 28
0.0100 0.0100 • 26
0.0100 0.0100 • 28
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a and 1993b.
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (m-1)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
0.7 1.5 • 10
1.0 1.5 • 40
1.3 1.5 • 29
1.2 1.5 • 17
1.2 1.5 • 21
1.2 1.5 • 5
• • t o
• • • 0
• • • 0
1.0 1.5 • 29
0.9 1.5 • 65
1.0 1.5 • 69
1.1 1.5 • 66
1.0 1.5 • 65
0.9 1.5 • 65
1.1 1.5 • 67
1.0 1.5 • 67
\
CBP Segment LE3— I
TSS (mg/l)
Med Rqmt Over N
• • « 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• » • 0
• • • 0
29.9 15 14.9 9
t • • 0
• • • 0
• » « 0
5.0 15 • 18
6.0 15 • 35
7.5 15 • 32
7.0 15 • 20
13.0 15 • 55
8.0 15 • 69
21.0 15 6.0 68
8.0 15 • 69
_ower Rappahannock I
CHL a (\ig/\)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• « ' • 0
7.0 15.0 • 5
8.0 15.0 • 21
7.0 15.0 • 31
6.4 15.0 • 20
9.2 15.0 • 4
• • • 0
• • • 0
• • • 0
• • • 0
9.8 15.0 • 8
7.8 15.0 • 49
8.0 15.0 • 68
9.6 15.0 • 66
7.4 15.0 • 65
7.9 15.0 • 69
7.1 15.0 • 68
8.2 15.0 • 69
^iver (Mesohaline)
DIN (mg/l)
Med Rqmt Over N
• • « 0
• • • 0
• • • 0
• • • 0
• • • 0
0.2342 0.1500 0.0842 15
0.1604 0.1500 0.0104 15
0.2213 0.1500 0.0713 5
0.1705 0.1500 0.0205 10
0.3000 0.1500 0.1500 2
0.0515 0.1500 • 9
• • • 0
• • '0
• • • 0
0.1000 0.1500 • 28
0.1000 0.1500 • 70
0.1000 0.1500 • 65
0.1000 0.1500 • 28
0.0800 0.1500 • 49
0.0900 0.1500 • 69
0.0800 0.1500 • 68
0.1600 0.1500 0.0100 69
DIP (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
0.0118 0.0100 0.0018 16
0.0118 0.0100 0.0018 19
0.0127 0.0100 0.0027 27
0.0126 0.0100 0.0026 20
0.0099 0.0100 • 5
0.0146 0.0100 0.0046 9
• • • 0
• • • 0
• • • 0
0.0100 0.0100 • 33
0.0100 0.0100 • 69
0.0100 0.0100 • 62
0.0100 0.0100 • 66
0.0100 0.0100 • 65
0.0100 0.0100 • 69
0.0100 0.0100 • 68
0.0100 0.0100 • 69
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a, 1993b.
1
Q.
x"
CO
-------
roi
SAV Growing Season Water Quality Medians Ry Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979.
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (m-1)
Med Rqmt Over N
• • • 0
• • • 0
« • • 0
• • • 0
• • • 0
2.1 2.0 0.1 22
2.9 2.0 0.9 69
2.4 2.0 0.4 106
2.9 2.0 0.9 65
3.6 2.0 1.6 10
3.6 2.0 1.6 5
« • • 0
• « • 0
• • • 0
1.8 2.0 • 7
1.8 2.0 • 20
1.6 2.0 • 24
1.6 2.0 • 22
1.6 2.0 • 19
1.8 2.0 • 26
1.8 2.0 • 25
1.8 2.0 • 22
CBP Segment T
TSS (mg/l)
Med Rqmt Over N
• • « 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• « • 0
• « • 0
• • • 0
• • • 0
• • • o
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
9.5 15 • 24
9.0 15 • 27
10.0 15 • 28
12.0 15 • 27
F4 - Upper York River
CHL a (ug/l)
Med Rqmt Over N
c
• • • 0
• • • 0
• • • 0
• • • 0
1.9 15.0 • 8
33.3 15.0 18.3 16
8.7 15.0 • 121
7.5 15.0 • 84
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
6.1 15.0 • 18
3.7 15.0 • 28
3.1 15.0 • 22
3.6 15.0 • 24
3.1 15.0 • 28
3.1 15.0 • 28
3.4 15.0 • 27
(Oligohaline)
DIN (mg/l)
Med Rqmt Over N
• • • n
• • • 0
• • • 0
• • • 0
• • • 0
0.1655 • • 42
0.1081 • • 15
0.1599 • • 10
0.0859 • • 32
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
0.2000 • • 13
0.2100 • • 28
0.1700 • • 28
0.2700 • • 22
0.2300 • • 24
0.2700 • • 27
0.2400 • • 28
0.1500 • • 27
DIP (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• * • 0
• • • 0
• • • 0
0.0130 0.0200 • 39
0.0102 0.0200. • 16
0.0099 0.0200 • 80
0.0211 0.0200 0.0011 58
• • • 0
• • • 0
• • • 0
• • • 0
• • « 0
0.0300 0.0200 0.0100 13
0.0150 0.0200 • 28
0.0100 0.0200 • 23
0.0250 0.0200 0.0050 22
0.0200 0.0200 • 24
0.0200 0.0200 • 27
0.0200 0.0200 • 28
0.0200 0.0200 • 27
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a and 1993b.
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (rrv1)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
2.4 1.5 0.9 21
4.8 1.5 3.3 55.
2.4 1.5 0.9 97
3.6 1.5 2.1 50
3.6 1.5 2.1 40
2.9 1.5 1.4 7
• • • 0
• • • 0
• • • o
2.91.5 1.4 18 24.0
2.91.5 1.4 39 20.0
3.61.5 2.1 40 28.5
3.6 1.5 2.1 32
3.6 1.5 2.1 32
4.8 1.5 3.3 40
3.6 1.5 2.1 42
3.6 1.5 2.1 36
CBP Segment RE
TSS (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • o
• • • 0
• • • 0
• • • 0
• • « 0
• • • 0
• • • 0
• • « 0
• • • 0
• • • o
• • • 0
• • • 0
15 9.0 7
15 5.0 13 8.5
15 13.5 14 9.2
24.5 - 15 9.5 6
44.0 15 29.0 24
40.0 15 25.0 41
42.0 15 27.0 41
36.0 15 21.0 40
"T4 - Middle York Rive
CHL a (ng/l)
Med Rqmt Over N
• • • 0
• t . o
• • • 0
• • • 0
• • • 0
5.5 15.0 • 9
47.5 15.0 32.5 17
9.1 15.0 • 101
8.5 15.0 • 63
3.4 15.0 • 12
• • • 0
• • • • o
• » • 0
• t • o
00.15000.150
15.0 • 270.12000.150
15.0 • 42 0.1600
7.0 15.0 • 33
10.4 15.0 • 33
10.0 15.0 • 42
8.1 15.0 • 42
12.4 15.0 • 41
r (Mesohaline)
DIN (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
0.1923 0.1500 0.0423 31
0.1793 0.1500 0.0293 17
0.1599 0.1500 0.0099 7
0.1369 .0.1500 • 22
0.1250 0.1500 • 4
• • • o
• • • 0
• • • 0
• • • 0
) • 210.02000.01000.01
) • 390.01000.0100 •
0.1500 0.0100 410.0100
0.2400 0.1500 0.0900 27
0.1700 0.1500 0.0200 29
0.2400 0.1500 0.0900 41
0.2050 0.1500 0.0550 42
0.1300 0.1500 • 40
DIP (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
0.0226 0.0100 0.0126 29
0.0174 0.0100 0.0074 17
0.0229 0.0100 0.0129 97
0.0239 0.0100 0.0139 62
0.0291 0.0100 0.0191 13
• • • 0
• •• • 0
• • • 0
• • • 0
10 21
38
0.0100 • 36
0.0200 0.0100 0.0100 33
0.0200 0.0100 0.0100 33
0.0200 0.0100 0.0100 41
0.0200 0.0100 0.0100 42
0.0300 0.0100 0.0200 40
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a, 1993b.
X
00
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (m-1)
Med Rqmt Over N
• • • 0
B » « 0
• • » 0
• • • 0
• « • 0
1.3 1.5 • 6
2.4 1.5 0.9 6
1.8 1.5 0.3 10
3.0 1.5 1.5 4
2.1 1.5 0.6 5
• • • 0
• • • 0
• • • o
• • • 0
1.5 1.5 • 15
1.5 1.5 • 30
1.7 1.5 0.2 30
1.7 1.5 0.2 27
1.8 1.5 0.3 31
1.6 1.5 0.1 30
1.5 1.5 • 29
1.6 1.5 0.1 33
CBP Segment L
TSS (mg/l)
Med Rqmt Over N
• • • 0
o • • 0
e • • 0
• • • 0
• • • 0
• » • 0
• • • 0
• • • 0
• • • o
• • • 0
• • • 0
• • • 0
• • • o
• • • o
5.0 15 • 5
7.5 15 • 6
6.0 15 • 6
18.0 15 3.0 3
12.0 15 • 16
11.5 15 • 30
16.0 15 1.0 30
21.0 15 6.0 33
E4 - Lower York River
CHL a (u.g/1)
Med Rqmt Over N
• • • 0
• • • 0
« • • 0
• • • 0
• • • 0
5.0 15.0 • 1
5.4 15.0 • 2
7.4 15.0 • 10
4.6 15.0 • 6
8.8 15.0 . • 4
• • • 0
• • • 0
• o • 0
« • • 0
« • • 0
4.2 15.0 • 15
6.4 15.0 • 30
13.9 15.0 • 27
7.1 15.0 • 31
8.5 15.0 • 30
5.2 15.0 • 30
9.9 15.0 • 33
(Polyhaline)
DIN (mg/l)
Med Rqmt Over N
o • • 0
• « • 0
• • • 0
.• « • 0
• • • 0
0.2233 0.1500 0.0733 6
0.1812 0.1500 0.0312 2
0.1804 0.1500 0.0304 2
0.2845 0.1500 0.1345 2
0.1599 0.1500 0.0099 2
t • • 0
• • • 0
• • • 0
• • • 0
0.1500 0.1500 • 14
0.1100 0.1500 • 30
0.1000 0.1500 • 27
0.1450 0.1500 • 6
0.0800 0.1500 • 29
0.1800 0.1500 0.0300 29
0.1250 0.1500 • 30
0.1700 0.1500 0.0200 33
DIP (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
0.0299 0.0200 0.0099 6
0.0270 0.0200 0.0070 2
0.0415 0.0200 0.0215 7
0.0459 0.0200 0.0259 5
0.0201 0.0200 0.0001 4
a • • 0
• • • 0
• • • 0
• • • 0
0.0200 0.0200 • 18
0.0100 0.0200 • 30
0.0100 0.0200 • 30
0.0100 0.0200 • 25
0.0100 0.0200 • 32
0.0100 0.0200 • 29
0..0250 0.0200 0.0050 30
0.0100 0.0200 • 33
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a and 1993b.
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (m 1)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
1.1 1.5 • 12
1.3 1.5 • 13
1.3 1.5 • 17
1.3 1.5 • 9
1.5 1.5 • 9
• • • 0
• • • 0
• • • o
• • • 0
1.2 1.5 • 19
0.9 1.5 • 42
1.0 1.5 • 40
1.1 1.5 • 39
1.2 1.5 • 38
1.0 1.5 • 35
1.0 1.5 • 31
1.2 1.5 • 33
CBP Segment
TSS (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • « 0
• • • 0
• • • • o
• • • 0
• • • o
• • • 0
• t « o
• • • 0
• • • 0
• • • o
14.2 15 • 20
10.0 15 • 44
7.0 15 • 43
9.0 15 • 44
16.0 15 1.0 40
22.0 15 7.0 36
13.6 15 • 33
12.0 15 • 36
WE4 - Mobjack Bay (
CHL a (\ig/\)
Med Rqmt Over N
• • • 0
• • • 0
• • • o
• • • 0
• • • 0
5.1 15.0 • 4
7.6 15.0 • 4
5.7 15.0 • 20
7.6 15.0 • 10
15.0 15.0 • 7
• • • 0
• • « 0
• • • 0
• « • 0
5.7 15.0 • 20
4.2 15.0 • 44
4.4 15.0 • 43
9.7 15.0 • 44
6.4 15.0 • 39
6.7 15.0 • 35
6.6 15.0 • 34
7.8 15.0 • 36
Polyhaline)
DIN (mg/l)
Med Rqmt Over N
• • • 0
• • « 0
• • » 0
• • • 0
• • • 0
0.1994 0.1500 0.0494 12
0.1690 0.1500 0.0190 4
0.1012 0.1500 • 3
0.2649 0.1500 0.1149 4
0.1400 0.1500 • 3
• • • 0
• • • 0
• • • 0
• • '0
0.0400 0.1500 • 19
0.0420 0.1500 • 44
0.0610 0.1500 • 43
0.0405 0.1500 • 44
0.0314 0.1500 • 40
0.0364 0.1500 • 36
0.0138 0.1500 • 34
0.0361 0.1500 • 36
DIP (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • "• 0
0.0246 0.0200 0.0046 12
0.0170 0.0200 • 4
0.0226 0.0200 0.0026 16
0.0250 0.0200 0.0050 10
0.0201 0.0200 0.0001 7
• • • 0
• • • 0
• • • 0
• • • 0
0.0100 0.0200 • 20
0.0100 0.0200 • 44
0.0100 0.0200 • 43
0.0110 0.0200 • 44
0.0020 0.0200 • 39
0.0030 0.0200 • 36
0.0030 0.0200 • 34
0.0049 0.0200 • 35
CO
c:
CT
CD
CO
CD
CL
O.
3"
Si
!£
co
-4
to
co
CD
ro
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Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a, 1993b.
U'S-ERA Headquarters Library
.Ortrt Mail code 3201
1200 Pennsylvania Avenue NW
Washington DC 20460
-o
(D
Z>
a.
x"
CO
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991.
Kd (m-1)
Med Rqmt Over N
• « • 0
• i • o
• • « 0
• • • 0
• • « 0
2.4 2.0 0.4 35
2.9 2.0 0.9 71
2.4 2.0 0.4 105
2.9 2.0 0.9 82
2.4 2.0 0.4 124
2.9 2.0 0.9 2
• • • 0
• • • 0
• • • 0
2.4 2.0 0.4 27
2.4 2.0 0.4 48
2.4 2.0 0.4 55
2.4 2.0 0.4 49
2.9 2.0 0.9 62
2.4 2.0 0.4 80
2.4 2.0 0.4 74
2.1 2.0 . 0.1 78
CBP Segment TF
TSS (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • « 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
17.0 15 2.0 86
18.0 ,15 3.0 96
20.0 15 5.0 98
18.0 15 3.0 98
5 - Upper James Rive
CHL a (ng/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
5.0 15.0 • 22
4.5 15.0 • 39
10.0 15.0 • 100
7.8 15.0 • 95
6.2 15.0 • 126
• « • 0
• « « o
• • • 0
• • • 0
• • • o
16.8 15.0 1.8 45
14.9 15.0 • 70
14.0 15.0 • 63
28.8 15.0 13.8 85
5.8 15.0 • 97
9.6 15.0 • 98
10.8 15.0 • 98
r (Tidal Fresh)
DIN (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
0.6686 • • 16
0.5500 • • 14
0.7201 • • 39
0.6242 • • 56
0.5250 • • 42
• • • 0
• « • 0
• • • 0
• • • 0
0.4500 • • 20
0.5500 • • 64
0.6000 • • 69
0.4950 • • 64
0.6100 • • 82
0.5250 • • 96
0.4750 • • 98
0.2350 • • 98
DIP (mg/l)
Med Rqmt Over N
. t • 0
• • • 0
• • • 0
• • • 0
• • • 0
0.0400 0.0200 0.0200 29
0.1299 0.0200 0.1099 41
0.0744 0.0200 0.0544 18
0.0860 0.0200 0.0660 58
0.0499 0.02 0.0299 129
• • • 0
• • • 0
• • • o
• • • o
0.0550 0.0200 0.0350 38
0.0400 0.0200 0.0200 64
0.0350 0.0200 0.0150 64
0.0300 0.0200 0.0100 64
0.0500 0.0200 0.0300 85
0.0500 0.0200 0.0300 96
0.0300 0.0200 0.0100 98
0.0300 0.0200 0.0100 98
CD
3
0.
x'
CD
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a and 1993b.
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (nrv1)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
3.6 2.0 1.6 11
3.6 2.0 1.6 35
2.9 2.0 0.9 40
3.6 2.0 1.6 33
3.6 2.0 1.6 43
2.9 2.0 0.9 32
• • • 0
• t « o
• • • 0
1.9 2.0 • 13
2.1 2.0 0.1 25
2.2 2.0 0.2 26
2.7 2.0 0.7 20
2.9 2.0 0.9 23
2.9 2.0 0.9 26
2.4 2.0 0.4 27
2.4 2.0 0.4 28
CBP Segment RE"
TSS (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • « 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • • 0
• • • 0
• « • 0
• • • 0
« • • 0
• • • 0
• • • 0
• • • 0
• • • 0
18.0 15 3.0 21
22.0 15 7.0 28
20.5 15 5.5 28
20.5 15 5.5 28
T5 - Middle James Riv
CHL a (ng/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
6.7 15.0 • 6
3.6 15.0 • 22
4.7 15.0 • 39
3.6 15.0 • 35
3.5 15.0 • 43
• • • 0
• • • 0
• • • 0
• » • 0
• • • 0
12.7 15.0 • 18
15.3 15.0 0.3 28
10.5 15.0 • 26
21.2 15.0 6.2 24
22.2 15.0 7.2 28
13.7 15.0 • 28
17.7 15.0 2.7 28
er (Oligohaline)
DIN (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • *0
0.6352 • • 6
0.7243 • • 14
0.5562 • • 15
0.7429 • • 15
0.8900 • • 15
• • • 0
• • • 0
• • • 0
• • • 0
0.3000 • • 8
0.1700 • • 25
0.1750 • • 28
0.2100 • • 25
0.1500 • • 24
0.2900 • • 27
0.0900 • • 28
0.1400 • • 28
DIP (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • '0
• • • 0
• i • 0
0.0304 0.0200 0.0104 10
0.0301 0.0200 0.0101 23
0.0257 0.0200 0.0057 29
0.0220 0.0200 0.0020 20
0.0290 0.0200 0.0090 44
• * • 0
• • • 0
• • • 0
• • • 0
0.0200 0.0200 • 15
0.0100 0.0200 • 25
0.0100 0.0200 • 27
0.0200 0.0200 • 26
0.0100 0.0200 • 23
0.0200 0.0200 • 28
0.0200 0.0200 • 28
0.0150 0.0200 • 28
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a, 1993b.
-------
Year
j ^-^*\
I3/U
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (nr1)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
1.5 1.5 • 13
2.4 1.5 0.9 5
2.1 1.5 0.6 42
1.6 1.5 0.1 25
2.1 1.5 0.6 14
2.9 1.5 1.4 23
1.5 1.5 • 34
• • • 0
• • • 0
• • • 0
1.9 1.5 0.4 3
1.5 1.5 • 56
1.8 1.5 0.3 56
1.8 1.5 0.3 53
1.8 1.5 0.3 51
2.1 1.5 0.6 47
1.9 1.5 0.4 56
1.9 1.5 0.4 54
CBP Segment LE
TSS (mg/l)
Med Rqmt Over N
• • • u
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
« • • 0
• • • 0
• • • 0
• « « 0
8.7 15 • 9
• • • 0
• • • 0
• • • 0
9.0 15 • 1
12.0 15 • 7
23.0 15 8.0 5
12.0 15 • 3
16.0 15 1.0 39
14.0 15 • 52
23.5 15 8.5 56
16.0 15 1.0 55
5 - Lower James Rive
CHL a (ug/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • i 0
• • • 0
1.8 15.0 • 3
4.8 15.0 • 32
4.2 15.0 • 25
1.9 15.0 • 10
2.9 15.0 • 23
• • • 0
• • « 0
• • • o
• • • 0
• • « o
5.3 15.0 • 36
4.3 15.0, • 55
4.8 15.0 • 52
5.9 15.0 • 52
6.6 15.0 • 52
4.9 15.0 • 56
5.2 15.0 • 53
r (Mesohaline)
DIN (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
0.5935 0.1500 0.4435 7
0.2611 0.1500 0.1111 28
0.2150 0.1500 0.0650 8
0.4700 0.1500 0.3200 5
0.5600 0.1500 0.4100 6
0.0934 0.1500 • 6
• • • 0
• • • 0
• • • 0
0.2600 0.1500 0.1100 4
0.1800 0.1500 0.0300 56
0.1500 0.1500 • 52
0.3400 0.1500 0.1900 25
0.2150 0.1500 0.0650 44
0.3700 0.1500 0.2200 52
0.2200 0.1500 0.0700 56
0.2200 0.1500 0.0700 55
DIP (mg/l)
Med Rqmt Over N
• • • 0
« • • 0
• • • 0
• • • 0
« • • 0
0.0341 0.0100 0.0241 7
0.0508 0.0100 0.0408 32
0.0428 0.0100 0.0328 21
0.0346 0.0100 0.0246 10
0.0350 0.0100 0.0250 22
0.0231 0.0100 0.0131 9
• • • 0
• • • 0
• • • 0
0.0500 0.0100 0.0400 4
0.0200 0.0100 0.0100 53
0.0200 0.0100 0.0100 54
0.0200 0.0100 0.0100 50
0.0350 0.0100 0.0250 52
0.0400 0.0100 0.0300 51
0.0300 0.0100 0.0200 56
0.0400 0.0100 0.0300 55
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a and 1993b.
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (nr1)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • o
2.5 2.0 0.5 3
3.0 2.0 1.0 4
2.9 2.0 0.9 4
2.0 2.0 • 3
• • • 0
3.9 2.0 1.9 1
• • • 0
• • • 0
• • • 0
• « • 0
4.8 2.0 2.8 1
3.6 2.0 1.6 7
3.6 2.0 1.6 7
2.9 2.0 0.9 7
3.6 2.0 1.6 7
2.9 2.0 0.9 7
3.6 2.0 1.6 7
CBP Segment I
TSS (mg/l)
Med Rqmt Over N
• « • 0
• • • 0
... o
• t » o
22.0 15 7.0 17
26.0 15 11.0 3
22.0 15 7.0 3
14.0 15 • 4
16.0 15 1.0 2
• • • 0
40.0 15 25.0 1
• • • 0
• t • o
• • • 0
• • • o
30.0 15 15.0 1
22.0 15 7.0 7
22.0 -15 7.0 7
28.0 15 13.0 7
16.0 15 1.0 7
22.0 15 7.0 7
24.0 15 9.0 7
ET1 - Northeast River
CHL a (^ig/l)
Med Rqmt Over N
• • • 0
76.0 15.0 61.0 23
« • • 0
• • • 0
60.0 15.0 45.0 19
52.5 15.0 37.5 19
37.5 15.0 22.5 3
33.0 15.0 18.0 4
27.9 15.0 12.9 3
• • • 0
61.8 15.0 46.8 1
• • • 0
• « • 0
• t • o
t • • o
43.7 15.0 28.7 1
26.7 15.0 11.7 7
34.4 15.0 19.4 7
52.0 15.0 37.0 7
46.4 15.0 31.4 7
31.4 15.0 16.4 7
41.9 15.0 26.9 7
Pligohaline)
DIN (mg/l)
Med Rqmt Over N
• • • • 0
0.1900 • • 23
• • • 0
• • • 0
0.4740 • • 19
0.2830 • -19
0.4510 • • 3
0.3750 • • 4
0.6985 • • 2
• • • 0
0.1370 • • 1
• • • 0
• • • 0
• • • 0
• • • 0
0.3100 • • 1
0.1280 • • 7
0.3580 • • 7
J>.1320 • • 7
0.3620 • • 7
0.5880 • • 7
0.0300 • • 6
DIP (mg/l)
Med Rqmt Over N
• • '0
0.0300 0.0200 0.0100 18
• • • 0
• • • 0
0.0300 0.0200 0.0100 19
0.0100 0.0200 • 19
0.0300 0.0200 0.0100 3
0.0300 0.0200 0.0100 4
0.0400 0.0200 0.0200 3
• • • 0
0.0100 0.0200 • 1
• • • 0
• • • 0
• • • 0
• • • 0
0.0100 0.0200 • 1
0.0040 0.0200 • 7
0.0060 0.0200 • 7
0.0040 0.0200 • 6
0.0040 0.0200 • 7
0.0040 0.0200 • 6
0.0040 0.0200 • 7
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a, 1993b.
-------
a
el-
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (nv1)
Med Rqmt Over N
• • • o
0
• • • 0
• • • 0
• • i 0
• • • 0
4.3 2.0 2.3 19
3.0 2.0 1.0 4
2.6 2.0 0.6 5
2.9 2.0 0.9 4
2.1 2.0 0.1 5
• • • 0
• • • 0
• • • 0
• « • 0
3.6 2.0 1.6 2
4.8 2.0 2.8 14
3.6 2.0 1.6 14
2.9 2.0 0.9 14
2.9 2.0 0.9 14
3.9 2.0 1.9 14
2.5 2.0 0.5 14
CBP Segment ET
TSS (mg/l)
Med Rqmt Over N
21.0 15 6.0 12
40.0 15 25.0 11
• • • 0
• • • 0
28.0 15 13.0 81
28.0 15 13.0 19
16.0 15 1.0 29
29.0 15 14.0 24
30.5 15 15.5 20
33.2 15 18.2 8
25.6 15 10.6 11
• • • 0
• • • 0
• • • 0
• • • 0
21.5 15 6.5 2
36.5 15 21.5 14
31.0 15 16.0 14
22.5 15 7.5 14
19.5 15 4.5 14
33.5 15 18.5 14
22.5 15 7.5 14
"2 - Elk/Bohemia River
CHL a (ng/l)
Med Rqmt Over N
31.6 15.0 16.6 14
57.0 15.0 42.0 63
• • • 0
• • • 0
31.5 15.0 16.5 89
25.8 15.0 10.8 30
36.0 15.0 21.0 52
18.8 15.0 3.8 24
17.4 15.0 2.4 23
20.5 15.0 5.5 8
17.0 15.0 2.0 7
• • • 0
• • • 0
• • • 0
• • • 0
37.6 15.0 22.6 2
20.1 15.0 5.1 14
14.3 15.0 • 14
17.9 15.0 2.9 14
17.0 15.0 2.0 ' 14
8.9 15.0 • 14
12.4 15.0 • 14
s (Oligohaline)
DIN (mg/l)
Med Rqmt Over N
• • • 0
0.4410 • • 52
• • • 0
• • • 0
0.8750 • • 89
1.1710 • • 30
0.6575 • • 52
0.6560 • • 25
1.5950 • • 15
• • • 0
2.4950 • • 3
• • « 0
• • • 0
• • • 0
• • • 0
0.5200 • • 2
0.5050 • -14
0.8350 • -14
0.6720 • • 14
1.0040 • • 14
0.9710 • • 14
0.4270 • • 14
DIP (mg/l)
Med Rqmt Over N
• t • 0
0.0400 0.0200 0.0200 38
• • • 0
• • • 0
0.0300 0.0200 0.0100 89
0.0400 0.0200 0.0200 30
0.0400 0.0200 0.0200 52
0.0300 0.0200 0.0100 25
0.0400 0.0200 0.0200 19
• • • 0
0.0300 0.0200 0.0100 3
• • • 0
• • • 0
• • • 0
• • • 0
0.0200 0.0200 • 2
0.0100 0.0200 • 14
0.0060 0.0200 • 14
0.0060 0.0200 • 11
0.0110 0.0200 • 14
0.0080 0.0200 • 11
0.0080 0.0200 • 14
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (m-1)
Med Rqmt Over N
• • • 0
• • • 0
• • • o
• • • 0
• « • 0 '
• • • 0
2.7 2.0 0.7 23
• • • 0
• • • o
• • • 0
• • • 0
• • • 0
• • • o
• • • o
• • • 0
3.6 2.0 1.6 1
3.6 2.0 1.6 7
4.8 2.0 2.8 7
4.8 2.0 2.8 7
4.8 2.0 2.8 7
4.8 2.0 2.8 7
4.8 2.0 2.8 7
CBP Segment E
TSS (mg/l)
Med Rqmt Over N
25.5 15 10.5 16
14.0 15 • 16
• • • 0
• • • 0
21.0 15 6.0 24
28.0 15 13.0 11
14.0 15 • 9
21.0 15 6.0 5
28.5 15 13.5 4
• • • 0
• • • 0
• • » o
• • • 0
• • • 0
• • • 0
24.0 15 9.0 1
20.0 15 5.0 7
27.0 15 12.0 7
20.0 15 5.0 7
18.0 15 3.0 7
20.0 15 5.0 7
25.0 15 10.0 7
ET3 - Sassafras River
CHL a (^g/l)
Med Rqmt Over N
42.0 15.0 27.0 20
54.0 15.0 39.0 48
• • » 0
• • « 0
45.0 15.0 30.0 26
30.0 15.0 15.0 11
42.8 15.0 27.8 32
79.5 15.0 64.5 5
69.2 15.0 54.2 4
• • • 0
• • • 0
• • • o
• • • 0
• • • o
• • • 0
61.4 15.0 46.4 1
41.1 15.0 26.1 7
62.8 15.0 47.8 7
66.3 15.0 51.3 6
79.7 15.0 64.7 7
73.1 15.0 58.1 6
62.1 15.0 47.1 7
[Oligohaline)
DIN (mg/l)
Med Rqmt Over N
• • « 0
0.0890 • • 31
• • • 0
• • • 0
0.3420 • • 26
0.7420 • -11
0.0915 • • 32
0.3890 • • 5
0.5980 • • 3
• • • 0
• • • 0
• • • 0
• • • 0
• • « 0
• • • 0
0.1200 • • 1
0.0360 • • 6
0.0660 • • 7
0.0540 • • 7
0.2200 • • 7
0.1120 • • 7
0.1320 • • 7
DIP (mg/l)
Med Rqmt . Over N
• • • 0
0.0300 0.0200 0.0100 24
• • • 0
• • • 0
0.0300 0.0200 0.0100 26
0.0600 0.0200 0.0400 11
0.0400 0.0200 0.0200 32
0.0300 0.0200 0.0100 5
0.0150 0.0200 • 4
• • • 0
* • • 0
• • • 0
• • • 0
• • • 0
• • • 0
0.0100 0.0200 • 1
0.0060 0.0200 • 6
0.0040 0.0200 • 7
0.0040 0.0200 • 7
0.0060 0.0200 • 7
0.0040 0.0200 • 6
0.0040 0.0200 • 7
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a, 1993b.
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (nr1)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
1.6 1.5 0.1 66
1.4 1.5 • 8
1.3 1.5 • 5
• • • 0
1.6 1.5 0.1 96
1.3 1.5 • 3
• • • 0
• • • 0
0.7 1.5 • 1
2.1 1.5 0.6 9
2.1 1.5 0.6 27
1.5 1.5 • 26
1.8 1.5 0.3 27
3.9 1.5 2.4 28
2.7 1.5 1.2 26
2.7 1.5 1.2 26
CBP Segment
TSS (mg/l)
Med Rqm? Over N
50.0 15 35.0 13
54.0 15 39.0 94
• • • 0
• • « 0
34.0 15 19.0 17
34.0 15 19.0 17
14.0 15 • 34
46.0 15 31.0 18
35.0 15 20.0 13
73.0 15 58.0 4
25.0 15 10.0 87
33.0 15 18.0 3
• • • 0
• • « 0
9.0 15 • 1
42.0 15 27.0 25
28.0 15 13.0 28
31.5 15 16.5 28
23.5 15 8.5 28
13.0 15 • 28
26.0 15 11.0 28
31.5 15 16.5 28
ET4 - Chester River (f
CHL a (ug/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• ' • • 0
30.0 15.0 15.0 20
8.3 15.0 • 17
18.0 15.0 3.0 91
31.5 15.0 16.5 24
22.5 15.0 7.5 t1
50.3 15.0 35.3 4
1.8 15.0 • 89
5.1 15.0 • 3
• • • 0
• • • 0
44.9 15.0 29.9 3
31.4 15.0 16.4 25
18.2 15.0 3.2 28
43.3 15.0 28.3 28
27.4 15.0 12.4 27
16.3 15.0 1.3 25
25.4 15.0 10.4- 27
14.4 . 15.0 • 27
vlesohaline)
DIN (mg/l)
Med Rqmt Over N
• • «0
• • • 0
• • • 0
• • • 0
0.7140 0.1500 0.5640 20
0.5340 0.1500 0.3840 17
0.0920 0.1500 • 91
0.3163 0.1500 0.1663 24
0.7265 0.1500 0.5765 10
0.7775 0.1500 0.6275 4
0.0780 0.1500 • 71
0.2930 0.1500 0.1430 3
• • • 0
• • • 0
0.1160 0.1500 • 1
0.1500 0.1500 • 24
0.0740 0.1500 • 27
0.2140 0.1500 0.0640 27
0.2800 0.1500 0.1300 27
0.7580 0.1500 0.6080 27
0.7320 0.1500 0.5820 27
0.2560 0.1500 0.1060 27
DIP (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
> • • 0
0.0400 0.0100 0.0300 20
0.0500 0.0100 0.0400 17
0.0300 0.0100 0.0200 91
0.0400 0.0100 0.0300 23
0.0400 0.0100 0.0300 13
0.0750 0.0100 0.0650 4
0.0100 0.0100 • 71
0.0200 0.0100 0.0100 3
• • • 0
• • • 0
0.0100 0.0100 • 1
0.0100 0.0100 • 25
0.0120 0.0100 0.0020 26
0.0080 0.0100 • 27
0.0120 0.0100 0.0020 28
0.0150 0.0100 0.0050 26
0.0060 0.0100 • 27
0.0090 0.0100 • 28
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a and 1993b.
-------
SAY Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (l/m)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • t o
1.4 1.5 • 161
0.9 1.5 • 11
1.0 1.5 • 9
• • • 0
1.2 1.5 • 3
• • • 0
• • • o
• • • 0
0.6 1.5 • 1
1.0 1.5 • 5
0.8 1.5 • 14
0.7 1.5 • 14
0.7 1.5 • 14
1.0 1.5 • 14
1.0 1.5 • 14
1.1 1.5 • 14
CBP Segment
TSS (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
11.0 15 • 10
23.0 15 8.0 14
10.0 15 14
11.0 15 • 12
19.0 15 4.0 9
• • • 0
12.0 15 • 3
• • • 0
• • • 0
• • • 0
5.5 15 • 2
7.5 15 • 12
4.5 15 • 14
2.0 15 • 14
5.5 15 • 14
11.0 15 • 14
14.5 15 • 14
16.5 15 1.5 14
EE1 - Eastern Bay (IV
CHL a(ug/1)
Med Rqmt Over N
10.5 15.0 • 16
21.0 15.0 6.0 11
• • • 0
• • • 0
13.5 15.0 • 15
6.8 15.0 • 14
18.0 15.0 3.0 204
12.9 15.0 • 12
15.6 15.0 0.6 9
• • • 0
9.9 15.0 • 3
• • « 0
• • • 0
• • • 0
8.1 15.0 • 2
9.0 15.0 • 12
5.5 15.0 • 14
7.1 15.0 • 14
7.7 15.0 • 14
10.8 15.0 • 11
10.1 15.0 • 14
9.4 15.0 • 11
lesohaline)
DIN (mg/1)
Med Rqmt Over N
• • • 0
• • *0
• • "0
• • • 0
0.3030 0.1500 0.1530 15
0.3390 0.1500 0.1890 14
0.0520 0.1500 • 201
0.0815 0.1500 • 12
0.3960 0.1500 0.2460 6
• • • 0
0.0410 0.1500 • 3
• • • 0
• • • 0
• • • 0
0.1390 0.1500 • 2
0.0850 0.1500 • 12
0.1200 0.1500 • 13
0.1090 0.1500 • 14
0.0860 0.1500 • 14
0.2690 0.1500 0.1190 14
0.1810 0.1500 0.0310 14
0.1010 0.1500 • 14
DIP (mg/1)
Med Rqmt Over N
0.1427 0.0100 0.1327 52
0.0200 0.0100 0.0100 11
• • '0
• • • 0
0.0100 0.0100 • 15
0.0400 0.0100 0.0300 14
0.0300 0.0100 0.0200 204
0.0200 0.0100 0.0100 12
0.0400 0.0100 0.0300 9
• • • 0
0.0300 0.0100 0.0200 3
• t • 0
• • • 0
• • • 0
0.0150 0.0100 0.0050 2
0.0100 0.0100 • 11
0.0095 0.0100 • 14
0.0060 0.0100 • 14
0.0040 0.0100 • 14
0.0060 0.0100 • 13
0.0040 0.0100 • 14
0.0040 0.0100 • 14
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a, 1993b.
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (l/m)
Med Rqmt Over N
• • • 0
• o • 0
• • • o
• • • 0
• « • o
o e • 0
2.4 1.5 0.9 105
« • • 0
• • • 0
• • • 0
1.9 1.5 0.4 8
« • • 0
• • • o
• • • o
1.9 1.5 0.4 5
2.1 1.5 0.6 11
2.7 1.5 1.2 28
1.9 1.5 0.4 28
2.3 1.5 0.8 28
2.1 1.5 0.6 27
3.3 1.5 1.8 28
2.4 1.5 0.9 28
CBP Segment I
TSS (mg/l)
Med Rqmt Over N
36.5 15 21.5 62
26.0 15 11.0 50
10.5 15 ° 4
• • • 0
20.0 15 5.0 78
19.0 15 4.0 24
16.0 15 1.0 48
17.3 15 2.3 31
12.0 15 • 31
9.5 15 • 18
13.9 15 • 37
« • » 0
• « • 0
• « • 0
12.0 15 • 11
20.5 15 5.5 24
15.8 15 0.8 28
13.0 15 • 28
16.0 15 1.0 28
15.3 15 0.3 28
20.5 15 5.5 28
19.0 15 4.0 28
ET5 - Choptank River i
CHL a (ug/1)
Med Rqmt Over N
• » « 0
• • • 0
32.5 15.0 17.5 4
• • • 0
30.0 15.0 15.0 78
15.0 15.0 • 24
21.0 15.0 6.0 151
16.5 15.0 1.5 31
21.5 15.0 6.5 30
12.0 15.0 » 18
14.0 15.0 • 30
° • • 0
« « o 0
• • • o
25.5 15.0 10.5 9
16.2 15.0 1.2 24
12.0 15.0 • 27
15.6 15.0 0.6 27
12.8 15.0 .• 28
10.6 15.0 • 28
14.0 15.0 • 28
14.6 15.0 • 24
Mesohaline)
DIN (mg/1)
Med Rqmt Over N
• » « 0
« • • 0
i » • 0
« » « 0
0.5240 0.15QC5 0.3740 79
1.2675 0.1500 1.1175 24
0.0850 0.1500 • 153
0.6450 0.1500 0.4950 31
1.1300 0.1500 0.9800 28
0.9655 0.1500 0.8155 18
0.9355 0.1500 0.7855 20
• e • '0
• < • 0
• • • 0
0.1570 0.1500 0.0070 9
0.1150 0.1500 • 24
0.1320 0.1500 • 27
0.1810 0.1500 0.0310 28
0.2000 0.1500 0.0500 27
0.6955 0.1500 0.5455 28
0.4060 0.1500 0.2560 27
0.1540 0.1500 0.0040 24
DIP (mg/1)
Med Rqmt Over N
» 0 • 0
• • • 0
0.0400 0.0100 0.0300 4
« • • 0
0.0400 0.0100 0.0300 79
0.0700 0.0100 0.0600 23
0.0400 0.0100 0.0300 153
0.0400 0.0100 0.0300 31
0.0400 0.0100 0.0300 33
0.0600 0.0100 0.0500 17
0.0300 0.0100 0.0200 20
• • • 0
• • • 0
• • • 0
0.0400 0.0100 0.0300 11
0.0200 0.0100 0.0100 24
0.0260 0.0100 0.0160 27
0.0250 0.0100 0.0150 28
0.0210 0.0100 0.0110 28
0.0260 0.0100 0.0160 27
0.0140 0.0100 0.0040 25
0.0100 0.0100 • 23
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a and 1993b.
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (l/m)
Med Rqmt Over N
• • • 0
• • • 0
« « • 0
• • • 0
• • • 0
1.4 1.5 • 1
1.2 1.5 • 66
• • • 0
. « • o
• • « 0
1.2 1.5 • 10
• • • 0
• • i 0
• t • o
1.2 1.5 • 4
1.0 1.5 • 7
0.9 1.5 • 22
0.9 1.5 • 26
0.9 1.5 • 25
1.0 1.5 • 28
1.2 1.5 • 28
1.1 1.5 • 28
CBP Segment EE2
TSS (mg/l)
Med Rqmt Over N
6.5 15 • 8
16.5 15 1.5 8
• • • 0
• • • 0
16.0 15 1.0 40
20.0 15 5.0 7
12.5 15 • 2
• • • 0
• • • 0
• • • 0
8.6 15 • 20
• • • 0
• • • o
• • • 0
6.0 15 • 7
10.0 15 • 12
8.0 15 • 22
6.5 -15 26
6.0 15 • 25
12.0 15 • 28
15.5 15 0.5 28
11.5 15 • 28
- Lower Choptank Riv
CHL a (ug/1)
Med Rqmt Over N
• • • 0
• • • 0
33.8 15.0 18.8 2.
• • • 0
22.1 15.0 7.1 40
10.5 15.0 • 7
12.0 15.0 • 74
• • • 0
• • • 0
• • • 0
12.0 15.0 • 20
• • • 0
• • • 0
• • • o
8.3 15.0 • 6
5.3 15.0 • 12
5.3 15.0 • 22
9.3 15.0 • 26
7.6 15.0 • 24
11.0 15.0 • 28
10.2 15.0 • 28
6.9 15.0 • 25
er (Mesohaline)
DIN (mg/1)
Med Rqmt Over N
• • • 0
• • • 0
0.0400 0.1500 • 2
• • • 0
0.1740 0.1500 0.0240 40
0.3240 0.1500 0.1740 7
0.0425 0.1500 • 74
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
0.1600 0.1500 0.0100 5
0.1100 0.1500 • 11
0.1280 0.1500 • 21
0.0560 0.1500 • 25
0.1080 0.1500 • 25
0.2260 0.1500 0.0760 28
0.1250 0.1500 • 28
0.1040 0.1500 • 24
DIP (mg/1)
Med Rqmt Over N
• • • 0
• • • 0
0.0100 0.0100 • 2
• « '0
0.0100 0.0100 • 40
0.0600 0.0100 0.0500 7
0.0300 0.0100 0.0200 74
• • • 0
• • • 0
• t • 0
• • • 0
t t • 0
• • • 0
• • • 0
0.0200 0.0100 0.0100 7
0.0100 0.0100 • 11
0.0100 0.0100 • 21
0.0080 0.0100 • 25
0.0060 0.0100 • 25
0.0080 0.0100 • 26
0.0040 0.0100 • 28
0.0040 0.0100 • 26
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a, 1993b.
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (l/m)
Med Rqmt Over N
• • • 0
• • • 0
• • • o
• • • 0
• • • 0
... o
2.8 1.5 1.3 50
• • • 0
• • • 0
• • • 0
• « • '0
• • • o
• • • o
• t • o
• • • o
• • • 0
3.3 1.5 1.8 14
2.9 1.5 1.4 14
3.6 1.5 2.1 14
3.6 1.5 2.1 14
4.2 1.5 2.7 14
3.6 1.5 2.1 14
CBP Segment E
TSS (mg/l)
Med Rqmt Over N
37.0 15 22.0 25
38.0 15 23.0 11
• • i o
8.0 15 • 1
24.0 15 9.0 61
28.0 15 13.0 15
20.0 15 5.0 18
29.3 15 14.3 15
22.0 15 7.0 15
• • • 0
• • • 0
• • • o
• • • 0
• • • o
• • t o
• • « o
23.0 15 8.0 13
24.0 15 9.0 14
29.5 15 14.5 14
23.5 15 8.5 14
28.5 15 13.5 14
28.0 15 13.0 13
:T6 - Nanticoke River
CHL a (ug/1)
Med Rqmt Over N
• • • 0
• • • 0
• « • 0
15.0 15.0 • 1
38.6 15.0 23.6 58
18.0 15.0 3.0 15
32.3 15.0 17.3 70
35.8 15.0 20.8 16
20.0 15.0 5.0 15
• • • 0
« • • 0
• • • 0
• « • o
• • • 0
• • • 0
• • • 0
16.1 15.0 1.1 13
14.7 15.0 • 13
19.4 15.0 4.4 14
13.2 15.0 • 14
19.7 15.0 4.7 14
16.2 15.0 1.2 12
^Mesohaline)
DIN (mg/1)
Med Rqmt Over N
0.0850 0.1500 • 21
0.2580 0.1500 0.1080 14
• • • 0
1.4080 0.1500 1.2580 1
0.4790 0.1500 0.3290 61
1.0280 0.1500 0.8780 15
0.0830 0.1500 • 70
0.1897 0.1500 0.0397 15
1.9230 0.1500 1.7730 9
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
0.3900 0.1500 0.2400 13
0.3140 0.1500 0.1640 14
0.3230 0.1500 0.1730 12
1.9920 0.1500 1.8420 12
0.6090 0.1500 0.4590 12
0.5920 0.1500 0.4420 12
DIP (mg/1)
Med Rqmt Over N
• • • 0
0.0450 0.0100 0.0350 7
• • • 0
0.0400 0.0100 0.0300 1
0.0300 0.0100 0.0200 61
0.0300 0.0100 0.0200 15
0.0300 0.0100 0.0200 62
0.0400 0.0100 0.0300 15
0.0400 0.0100 0.0300 15
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
0.0100 0.0100 • 13
0.0100 0.0100 • 14
0.0080 0.0100 • 12
0.0180 0.0100 0.0080 13
0.0060 0.0100 • 13
0.0070 0.0100 • 14
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a and 1993b.
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (l/m)
Med Rqmt Over N
• • • 0
• • • 0
• • • o
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• » • 0
• « • 0
• • • • 0
• • • 0
• • • 0
2.9 1.5 1.4 7
2.4 1.5 0.9 7
2.9 1.5 1.4 7
3.6 1.5 2.1 7
3.6 1.5 2.1 7
2.9 1.5 1.4 7
CBP Segment E
TSS (mg/l)
Med Rqmt Over N
31.0 15 16.0 40
36.0 15 21.0 30
• » • 0
• • • 0
27.0 15 12.0 74
26.0 15 11.0 12
26.0 15 11.0 18
24.0 15 9.0 15
26.0 15 11.0 15
• • • 0
• • • 0
• • • 0
« • • 0
• • • 0
• • • 0
• • • 0
20.0 15 5.0 7
17.0 15 2.0 7
25.0 15 10.0 7
29.0 15 14.0 7
38.0 15 23.0 7
29.0 15 14.0 7
ET7 - Wicomico River
CHL a (ug/1)
Med Rqmt Over N
« • • 0
• • • 0
« • • 0
• • • 0
60.0 15.0 45.0 74
15.0 15.0 • 19
54.0 15.0 39.0 18
52.5 15.0 37.5. 15
22.8 15.0 7.8 15
• • « 0
• • • 0
• • • o
• . • • 0
• • • 0
• • • 0
• • • 0
12.9 15.0 • 7
9.5 15.0 • 6
19.1 15.0 4.1 7
16.7 15.0 1.7 7
17.9 15.0 2.9 7
15.0 15.0 • 7
Mesohaline)
DIN (mg/1)
Med Rqmt Over N
0.9500 0.1500 0.8000 40
0.7500 0.1500 0.6000 40
• • • 0
• • • 0
0.8235 0.1500 0.6735 74
0.9980 0.1500 0.8480 19
0.4000 0.1500 0.2500 18
0.9670 0.1500 0.8170 15
1.5430 0.1500 1.3930 9
• • • 0
• • • 0
• « • 0
• « • 0
• » • 0
• • • 0
• • • 0
0.1500 0.1500 • 7
0.1300 0.1500 • 7
0.1400 0.1500 • 6
0.4860 0.1500 0.3360 7
0.0530 0.1500 • 6
0.1810 0.1500 0.0310 5
DIP (mg/1)
Med Rqmt Over N
t • • 0
0.1000 0.0100 0.0900 20
• • . • 0
• • • 0
0.0600 0.0100 0.0500 74
0.0400 0.0100 0.0300 19
0.0300 0.0100 0.0200 18
0.0500 0.0100 0.0400 15
0.0600 0.0100 0.0500 15
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • « 0
• • • 0
0.0160 0.0100 0.0060 7
0.0140 0.0100 0.0040 7
0.0140 0.0100 0.0040 6
0.0090 0.0100 • 6
0.0060 0.0100 • 7
0.0040 0.0100 • 6
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a, 1993b.
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1930
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (l/m)
Med Rqmt Over N
• « • 0
• • • 0
• • « 0
• • • 0
• • • 0
• • • o
2.4 1.5 0.9 3
• • • 0
• • « 0
• • « 0
• • « 0
• • « 0
• • • 0
• • • 0
• • • 0
• • • 0
2.4 1.5 0.9 7
2.1 1.5 0.6 7
2.9 1.5 1.4 7
2.1 1.5 0.6 7
2.9 1.5 1.4 7
2.1 1.5 0.6 7
CBP Segment
TSS (mg/l)
Med Rqmt Over N
• • « 0
• • • 0
• • • 0
• t • o
10.0 15 • 1
24.0 15 9.0 3
• • • 0
• « » 0
• • • o
• • • 0
• « • 0
• • • o
• • • 0
• « « o
• • • o
« • • 0
16.0 15 1.0 7
18.0 15 3.0 7
21.0 15 6.0 7
30.0 15 15.0 7
34.0 15 19.0 7
22.0 15 7.0 7
ET8 - Manokin River (
CHL a (ug/1)
Med Rqmt Over N
• • • 0
• ° • 0
• • • 0
• • • 0
12.0 15.0 • 1
12.0 15.0 • 3
20.1 15.0 5.1 6
• • « 0
• • • 0
• • • o
• • • 0
• * • o
• • • 0
• • • 0
• • • 0
• • • 0
12.7 15.0 • 7
11.1 15.0 • 7
12.6 15.0 • 7
13.2 15.0 • 7
14.5 15.0 • 7
10.0 15.0 • 4
Vlesohaline)
- DIN (mg/1)
Med Rqmt Over N
• • ' • 0
• • "0
« o * 0
• • • 0
0.0610 0.1500 • 1
0.3350 0.1500 0.1850 3
0.0320 0.1500 • 6
• • "0
• • ° 0
• • « 0
• « • 0
• » *0
• • • 0
• • • 0
• • • 0
• • • 0
0.0420 0.1500 • 7
0.0520 0.1500 • 7
0.0390 0.1500 • 6
0.0360 0.1500 • 7
0.0560 0.1500 • 6
0.0640 0.1500 • 6
DIP (mg/1)
Med Rqmt Over N
• • • 0
0 0 • 0
• • • 0
• • • 0
0.0300 0.0100 0.0200 1
0.0300 0.0100 0.0200 3
0.0500 0.0100 0.0400 6
• > • 0
e • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
0.0100 0.0100 • 7
0.0060 0.0100 • 7
0.0050 0.0100 • 6
0.0040 0.0100 • 7
0.0040 0.0100 • 7
0.0040 0.0100 • 7
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a and 1993b.
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (l/m)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • o
2.3 1.5 0.8 6
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
1.5 1.5 ' • 7
1.3 .1.5 • 7
1.5 1.5 • • 7
1.5 1.5 • 7
1.8 1.5 0.3 7
1.8 1.5 0.3 7
CBP Segment E
TSS (mg/l)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
5.0 15 • 2
• • • 0
• • • 0
• • • 0
• • • 0
• • t o
• • • 0
• • • 0
• • • 0
13.0 15 • 7
10.0 15 • 7
17.0 15 2.0 7
21.0 15 6.0 7
25.0 15 10.0 7
22.0 15 7.0 7
T9 - Big Annemessex
CHL a (ug/1)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• « • 0
• • • 0
• • • 0
14.9 15.0 • 8
31.5 15.0 16.5 2
• • • 0
• • • 0
• • • 0
• • • o
« • • 0
• • • 0
« • • 0
• • • o
6.4 15.0 • 7
8.2 15.0 • 7
11.4 15.0 • 7
9.6 15.0 • 7
10.2 15.0 • 7
10.9 15.0 • 4
(Mesoha.line)
DIN (mg/1)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
0.0210 0.1500 • 8
0.0820 0.1500 • 2
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
« • • 0
• • « 0
• « • 0
0.0400 0.1500 • 7
0.0480 0.1500 • 7
0.0360 0.1500 • 6
0.0320 0.1500 • 7
0.0660 0.1500 • 6
0.0710 0.1500 • 6
DIP (mg/1)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
t • ' » 0
• • • 0
0.0400 0.0100 0.0300 8
0.0100 0.0100 • 2
• • • • 0
• • • 0
• • • 0
• • • 0
• • • 0
t t • 0
• • • 0
• • • 0
0.0100 0.0100 • 7
0.0040 0.0100 • 7
0.0040 0.0100 • 7
0.0060 0.0100 • 7
0.0040 0.0100 • 7
0.0040 0.0100 • 7
CO
cr
CD
(3
CD
d.
co
S.
o' O
§5
CO D>
Q>
01
=i
3.
cr
5. Si.
$3
8
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a, 1993b.
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1935
1986
1987
1988
1989
1990
1991
Kd (!/m)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
2.9 1.5 1.4 30
• • • 0
• • • o
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
2.7 1.5 1.2 6
3.6 1.5 2.1 7
2.9 1.5 1.4 7
4.8 1.5 3.3 7
7.3 1.5 5.8 7
3.6 1.5 2.1 7
CBP Segment E"
TSS (mg/l)
Med Rqmt Over N
• • • 0
22.0 15 7.0 59
• • • 0
• • • 0
16.0 15 1.0 107
15.0 15 • 16
18.0 15 3.0 25
15.0 15 • 19
16.0 15 1.0 14
6.0 15 • 3
10.0 '15 • 4
• • • 0
• « • 0
t • • 0
• • • 0
• • • 0
23.5 15 8.5 7
16.0 15 1.0 7
10.0 15 • 7
12.0 15 • 7
13.0 15 • 7
16.0 15 1.0 7
no - Pocomoke River
CHL a (ug/1)
Med Rqmt Over N
• • • 0
... 0
• • • 0
• • • 0
28.5 15.0 13.5 107
15.0 15.0 • 15
21.0 15.0 6.0 64
18.8 15.0 3.8 20
10.1 15.0 • 18
5.4 15.0 • 3
• • t o
• • » 0
• • • 0
• • • 0
• • • 0
« • • 0
9.6 15.0 • 7
7.5 15.0 • 7
9.6 15.0 • 7
3.0 15.0 • 5
2.7 15.0 • 7
10.3 15.0 • 6
(Mesohaline)
DIN (mg/1)
Med Rqmt Over N
• • • 0
0.8795 0.1500 0.7295 76
• • • 0
• • • 0
0.4675 0.1500 0.3175 106
0.8500 0.1500 0.7000 16
0.2220 0.1500 0.0720 62
0.3302 0.1500 0.1802 20
0.9360 0.1500 0.7860 12
1.1240 0.1500 0.9740 3
0.8360 0.1500 0.6860 3
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
0.3420 0.1500 0.1920 7
0.5720 0.1500 0.4220 7
0.7010 0.1500 0.5510 6
1.0520 0.1500 0.9020 7
0.8310 0.1500 0.6810 6
0.6610 0.1500 0.5110 6
DIP (mg/1)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• t • 0
0.0500 0.0100 0.0400 107
0.0750 0.0100 0.0650 16
0.0550 0.0100 0.0450 62
0.0433 0.0100 0.0333 20
0.1000 0.0100 0.0900 19
0.0800 0.0100 0.0700 3
0.1200 0.0100 0.1100 3
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
0.0400 0.0100 0.0300 7
0.0380 0.0100 0.0280 7
0.0430 0.0100 0.0330 6
0.0740 0.0100 0.0640 7
0.0460 0.0100 0.0360 7
0.0380 0.0100 0.0280 7
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a and 1993b.
-------
SAV Growing Season Water Quality Medians By Segment (1970 to 1991)
Year
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Kd (l/m)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • o
• • • o
• • • 0
2.2 1.5 0.7 17
• • • 0
• • • 0
• • • 0
• • • 0
• • • o
• « • o
• • • 0
• • • 0
• • • 0
0.9 1.5 • 12
1.1 1.5 • 13
1.0 1.5 • 14
0.9 1.5 • 14
1.0 1.5 • 14
1.2 1.5 • 14
CBP Segment
TSS (mg/l)
Med Rqmt Over N
22.0 15 7.0 5
24.0 15 9.0 5
• • • • 0
• • • 0
22.0 15 7.0 51
26.0 15 11.0 20
29.0 15 14.0 12
21.0 15 6.0 11
40.0 15 25.0 9
• • • 0
25.2 15 10.2 16
• • • 0
• • • 0
• • • 0
• • • 0
• • • o
6.5 15 • 12
9.0 -15 -13
11.0 15 • 14
15.5 15 0.5 14
20.5 15 5.5 14
20.5 15 5.5 14
EE3 - Tangier Sound (
CHL a (ug/1)
Med Rqmt Over N
• • • 0
• • • 0
• • • o
• • • 0
25.5 15.0 10.5 51
16.3 15.0 1.3 20
16.8 15.0 1.8 35
17.5 15.0 2.5 12
7.5 15.0 • 9
• • • 0
• • • 0
• • • o
• • • 0
• • • 0
• • • 0
• • • o
4.8 15.0 • 12
7.5 15.0 • 13
8.7 15.0 • 14
7.8 15.0 • 12
6.9 15.0 • 13
7.8 15.0 • 11
Mesohaline)
DIN (mg/1)
Med Rqmt Over N
• • « 0
0.0210 0.1500 • 5
• • • 0
• • • 0
0.1950 0.1500 0.0450 51
0.3435 0.1500 0.1935 20
0.0330 0.1500 • 36
0.0982 0.1500 • 12
0.3480 0.1500 0.1980 6
• • • 0
0.0652 0.1500 • 16
• • • 0
• • • 0
• • • 0
• • • 0
• • • 0
0.1290 0.1500 • 12
0.0720 0.1500 • 13
0.0640 0.1500 • 13
0.0910 0.1500 • 14
0.0890 0.1500 • 14
0.1040 0.1500 • 13
DIP (mg/1)
Med Rqmt Over N
• • • 0
• • • 0
• • • 0
• • • 0
0.0200 0.0100 0.0100 51
0.0300 0.0100 0.0200 18
0.0300 0.0100 0.0200 36
0.0300 0.0100 0.0200 12
0.0500 0.0100 0.0400 10
• • • 0
0.0157 0.0100 0.0057 16
• • • 0
• • • 0
• • • 0
• • • • 0
• • • 0
0.0100 0.0100 • 12
0.0060 0.0100 • 13
0.0060 0.0100 • 14
0.0070 0.0100 • 14
0.0040 0.0100 • 14
0.0040 0.0100 • 14
Med = Median Value for Growing Season
Rqmt = Habitat Requirement
Over = Amount the Median Exceeds Requirement
N = Number of Observations
Sources: Chesapeake Bay Program, 1993a, 1993b.
-------
Table C-l. Chesapeake Bay SAV Distribution and Abundance by State in Hectares
Year Maryland Virginia District of Columbia Delaware Baywide
1971
1974
1978
1979
1980
1981
1984
1985
1986
1987
1989
1990
1991
Tier I Goal
Tier III Target
•
•
8,367
(2)
23
371
5,488
9,638
8,371
9,417
10,278
9,523
9,343
24,211
130,272
490 11
3,302'
8,530
(2)
6,411
7,682
9,940
10,262
10,969
10,750
13,881
14,774
16,265
21,702
116,799
•
•
0
*
•
•
5
74
85
67
88
97
119
112
486
•
e
0
•
•
•
0
0
0
0
0
0
0
0
102
(1)
(1)
16,897
(2)
6,434
8,053
15,433
19,974
19,425
20,234
24,247
24,394
25,727
46,025
247,659
(•) = No aerial survey data available for that year.
(1) = Partial aerial survey of Virginia's Chesapeake Bay shoreline; no baywide average data available.
(2) = Aerial photography acquired in 1979 for sections of Maryland and Virginia with only selected areas (4,955 hectares in Maryland and 71
hectares in Virginia) of the survey photography interpreted and mapped.
Sources: Anderson and Macomber, 1980; Batiuk et al., 1992; Chesapeake Bay Program, unpublished data a, b; Orth et al., 1979, 1985, 1986, 1987,
1989, 1991, and 1992; Orth and Gordon, 1975; Orth and Nowak ,1990.
-------
Table C-2. Maryland SAV Distribution and Abundance in Hectares
Density
Year Not Recorded Density 1 Density 2 Density 3 Density 4 Total
1971
1974
1978
1979
1980
1981
1984
1985
1986
1987
1989
1990
1991
•
•
8,360
(1)
•
•
•
•
•
•
•
•
•
•
•
•
•
•
10
2,191
2,375
2,513
2,593
2,306
2,220
2,010
•
•
5
•
13
41
658
1,895
1,444
817
1,803
2,015
1,274
•
•
2
•
7
307
1,122
2,869
1,723
1,541
1,430
2,119
2,273
•
•
•
•
2
12
1,517
2,499
2,690
4,466
4,737
3,169
3,786
•
•
8,367
(1)
22
370
5,488
9,638
8,370
9,417
10,276
9,523
9,343
cr
CD
CO
CD
Q.
11
s1
fO
o' O
si
§1
il
Si.
CO
-J
CO
co
(•) = No aerial survey data available for that year or density category.
(1) = Aerial photography was acquired in 1979 for sections of Maryland with only selected areas (4,955 hectares) of the survey photography were
interpreted and mapped.
Sources: Anderson and Macomber, 1980; Chesapeake Bay Program, unpublished data a; Orth et al., 1985, 1986, 1987, 1989, 1991, and 1992; Orth
and Nowak, 1990.
-------
Table C-3. Virginia SAV Distribution and Abundance in Hectares
Density
Year Not Recorded Density 1 Density 2 Density 3 Density 4 Total
1971
1974
1978
1979
1980
1981
1984
1985
1986
1987
1989
1990
1991
4,901'
3,302'
•
(2)
•
•
•
•
•
•
•
•
•
•
•
911
•
365
155
596
829
1,269
1,045
1,023
1,340
1,189
*
*
2,382
•
1,932
1,207
2,199
2,182
2,131
2,478
2,545
3,585
3,568
•
•
4,227
•
2,631
3,694
2,732
3,619
2,023
2,044
2,299
1,867
2,452
•
•
1,011
•
1,483
2,626
4,413
3,633
5,547
5,182
8,013
7,981
9,056
4,901
3,302
8,531
(2)
6,411
7,682
9,940
10,263
10,970
10,749
13,880
14,773
16,265
CO
CT
CD
(O
(D
Q.
.
"
a
3 OJ
3' =.
§1
(0 O
-
CD D>
*•< ^
» -
as
5o
CT C.
C 0>
(O
CO
(•) = No aerial survey data available for that year or density category.
(1) = Partial aerial survey of Virginia's Chesapeake Bay shoreline; does not include Eastern Shore shoreline.
(2) = Aerial photography was acquired in 1979 for sections of Virginia with only selected areas (71 hectares) of the survey photography interpreted
and mapped. ;
Sources: Chesapeake Bay Program, unpublished data a, b; Orth et al., 1979, 1985, 1986, 1987, 1989, 1991, and 1992; Orth and Gordon, 1975; Orth
and Nowak, 1990.
-------
Table C-4. District of Columbia SAV Distribution and Abundance in Hectares
Density
Year Not Recorded Density 1 Density 2 Density 3 Density 4 Total
i r>*7 i
17/1
1974
1978
1979
1980
1981
1984
1985
1986
1987
1989
1990
1991
*
•
•
•
*
•
•
•
•
*
*
*
•
•
•
«
•
•
•
0
24
3
1
1
0
0
«
•
•
•
•
•
3
34
20
1
2
3
9
o
•
•
•
•
•
0
13
16
0
0
3
5
•
•
*
*
•
•
1
3
46
64
85
90
104
•
•
•
•
•
•
4
74
85
66
88
96
118
CO
"
0>
CO
o.
>
CD 3
8
"
M
S! 9,
(•) = No aerial survey data available for that year or density category.
Sources: Orth et al., 1985, 1986, 1987, 1989, 1991, and 1992; Orth and Nowak, 1990.
-------
Appendix D. Maryland Department of Natural Resources SAV Ground Survey Percent Stations Vegetated Data by Chesapeake Bay
Program Segment: 1971 to 1990
YEAR
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
YEAR
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
CB1
0
0
0
17
13
10
13
3
7
0
3
17
7
0
4
17
13
7
-
-
6
LE2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
-
50
60
-
-
0
CB2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
wn
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
-
CB3
0
0
4
0
14
8
0
12
8
15
8
0
5
0
17
8
0
0
22
0
0
WT2
0
0
0
0
0
0
25
0
25
50
25
25
25
0
25
0
0
0
0
0
0
CB4
0
0
2
0
0
0
0
2
0
0
0
0
0
0
0
0
0
0
0
0
WT3
0
0
14
14 •
14
14
29
0
14
L29
14
0
57
43
43
20
57
0
0
0
0
CBS
0
100
10
8
6
8
4
0
0
4
8
4
4
0
4
4
4
0
8
15
3
WT4
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
EE1
0
-
37
40
24
46
31
29
14
38
5
4
20
7
19
10
47
-
0
2
9
WT5
0
0
5
10
-
10
14
14
10
0
10
0
5
0
0
0
0
0
0
0
0
EE2
0
-
17
22
2
42
28
29
24
21
2
7
5
2
18
5
7
45
18
12
4
WT6
0
-
29
29
-
29
43
14
29
29
14
0
0
0
29
0
0
0
-
-
8
EE3
100
0
10
17
11
12
8
5
2
6
9
3
5
4
7
8
18
38
16
14
17
WT7
0
-
33
33
-
50
25
33
25
25
8
0
8
0
0
0
0
0
0
0
0
ET1
0
0
0
0
0
0
0
0
14
0
0
0
0
14
0
0
0 .
0
0
0
0
WT8
0
0
0
0
0
14
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
ET2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
RET1
0
0
0
0
0
0
0
11
0
0
0
7
0
-
-
•
0
0
-
-
0
ET3
0
-
0
10
0
0
0
0
0
0
10
0
10
0
0
11
0
-
11
20
10
RET2
0
0
0
0
0
0
0
0
0
0
0
0
0
-
-
-
.
100
-
-
17
ET4
0
-
29
31
25
26
46
46
36
36
14
0
11
25
14
11
50
-
11
0
8
TF1
0
0
0
L 0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0.
0
ET5
0
-
6
18
0
11
6
6
6
17
0
0
0
0
0
0
0
0
0
0
0
TF2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
71
-
0
17
ET6
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
'
ET7
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
i
•
ET8
0
0
0
27
9
9
27
0
0
0
9
9
0
9
18
18
100
-
18
20
13
,
,
<-•
ET9
0
-
42
9
33
25
18
0
0
0
8
0
17
13
25
8
25
-
0
20
,, „ ,
'
LE1
0
-
7
25
4
3
0
4
0
0
0
0
0
0
0
4
7
•
0
0
l""'l 1
-•
Source: Chesapeake Bay Program, unpublished data c.
-------
Appendix E
Table E-l. Quartiles of Average Daily Susquehanna River Flow per Month (1950 to 1991)
YEAR
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
JAN
4
4
4
4
1
3
1
3
3
3
3
1
3
2
3
1
1
2
1
2
1
2
3
4
4
4
3
1
4
5
2
1
2
1
1
2
3
2
2
2
3
4
FEB
3
4
3
3
3
2
3
2
1
2
3
4
1
1
1
2
3
1
2
1
4
4
2
4
3
4
5
1
2
2
1
5
3
2
2
2
4
1
3
1
4
3
MAR
3
3
3
3
2
4
4
2
3
2
1
3
3
4
4
1
3
3
2
1
1
4
4
2
2
3
2
4
4
4
2
1
3
1
1
1
4
2
1
1
1
2
APR
4
3
3
2
2
1
4
4
4
3
4
4
4
1
3
2
1
2
1
2
4
2
3
3
3
1
1
3
3
2
4
1
3
4
2
1
2
3
1
2
1
1
MAY
2
1
4
4
4
1
3
2
4
2
4
3
1
2
3
1
3
4
3
2
2
3
4
3
2
3
2
1
4
2
2
2
1
4
3
1
1
1
3
5
3
1
JUN
3
3
2
4
2
1
3
1
3
1
4
3
1
2
1
1
2
2
4
2
2
2
5
4
2
4
4
1
3
3
2
3
5
3
4
1
3
1
1
5
3
1
JUL
2
3
2
2
1
1
4
1
4
1
3
2
1
1
1
1
1
2
3
2
4
1
5
3
4
3
4
3
2
2
2
3
3
3
4
2
3
3
2
5
4
1
AUG
3
2
2
2
1
4
4
1
3
1
2
3
1
1
1
1
1
4
1
4
3
3
3
3
3
2
4
3
4
3
2
2
2
2
4
2
4
1
2
3
4
1
SEP
4
2
3
1
2
2
4
1
3
2
4
2
1
1
1
1
1
3
3
2
2
3
2
3
4
5
3
5
3
4
1
2
1
1
2
3
2
4
3
3
4
1
OCT
4
1
1
1
3
5
3
1
3
3
2
1
3
1
1
2
2
4
2
1
3
2
2
3
3
5
5
5
2
5
1
4
1
2
2
3
3
3
2
4
5
1
NOV
•. 4
2"
2
1
2
4
3
1
2
4
1
1
3
1
1
1
1
3
3
3
4
2
4
3
2
3
3
4
2
4
1
3
1
2
2
4
4
2
3
3
4
1
DEC
4
3
3.
2
3
1
4
3
1
4
1 •
1
1
1
1
1
2
3
2
2
3
4
5
4
3
2
2
4
2
3
1
2
2
4
3
3
4
3
1
1
4
2
Note: Mean monthly flows were categorized according to the quartiles for that month, with a fifth category for extremely
high flows. 1 + first quartile (0-25%), 2 = second (25-50% or median), 3 = third (50-75%), 4 = fourth (75%-category), 5 =
exceeded 75% +1.5 times interquartile range (75th percentile - 25th percentile). Data from Conowingo were used.
Trends in the Distribution, Abundance, and Habitat Quality of
Submerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
E-1
-------
Appendix E
Table E-2. Quartiles of Average Daily Potomac River Flow per Month (1950 to 1991).
YEAR
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
' 1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
JAN
2
r
O1
L
i*
•
;)
i
!>
!3~^
1
3
1
2
2
4
3
1
2
3
1
3
4
2
3
4
3
4
1
4
5
4
1
2
1
2
1
1
2
3
2
3
5
FEB
4
4
3
3
1
2
3
3
1
1
2
4
2
1
2
3
2
1
3
1
3
4
4
4
1
3
2
1
1
4
1
2
4
3
4
3
4
2
2
1
3
2
MAR
2
2
3
4
2
4
2
1
3
1
2
4
4
4
4
3
1
4
3
1
1
2
3
2
1
3
1
3
4
4
2
1
3
3
4
1
3
2
1
2
1
3
APR
1
3
4
3
1
2
3
3
4
2
4
4
3
1
3
3
1
1
1
1
4
1
3
4
3
2
2
3
2
3
4
2
2
4
4
1
2
4
1
1
2
2
MAY
3
2
4
3
2
1
1
1
4
2
4
3
2
1
3
1
3
3
2
1
2
3
4
3
2
3
1
1
4
3
4
2
1
4
4
2
1
3
5
5
2
1
JUN
3
4
2
3
1
3
2
1
2
3
4
2
2
2
1
1
1
1
3
1
2
4
5
4
4
3
2
1
2
4
3
4
5
3
1
3
1
1
2
4
3,
•
JUL
3
3
3
2
1
2
4
1
4
1
2
2
2
1
1
1
1
3
2
1
4
2
5
3
3
4
2
1
4
3
3
3
4
2
4
2
1
3
1
5
4
•
AUG
2
2
3
2
2
5
4
1
4
2
3
2
1
1
1
1
1
4
2
4
3
4
4
3
2
3
2
1
5
3
3
1
3
2
5
3
1
1
1
4
3
•
SEP
5
2
4
2
2
4
3
1
2
1
3
2
1
1
1
1
4
3
2
4
1
4
3
3
3
5
2
1
3 ^
5
1
3
2
1
3
2
1
4
2
4
3
•
OCT
4
1
2
1
4
3
3
2
1
3
2
3
1
1
2
1
4
3
1
2
2
5
4
3
2
5
5
2
1
5
1
2
2
3
3
3
1
3
1
4
5
•
NOV
4
1
4
1
3
2
3
1
1
2
1
2
3
1
1
1
2
2
3
2
4
3
5
3
1
4
4
4
1
5
2
2
1
4
3
5
2
3
2
3
3
•
DEC
4
2
3
1
3
1
3
3
1
2
1
2
1
2
2
1
2
4
1
2
4
4
5
4
4
2
2
4
3
3
1
1
2
4
3
4
3
3
1
1
3
•
Note: Mean mo ithly flows were categorized according to the quartiles for that month, with a fifth category for extremely
high flows. 1 + first quartile (0-25%), 2 = second (25-50% or median), 3 = third (50-75%), 4 = fourth (75%-category), 5 =
exceeded 75% + 1.5 times interquartile range (75th percentile - 25th percentile). Data from Little Falls were used.
E-2
Trends in the Distribution, Abundance, and Habit-, duality of
Sutr-nerged Aquatic Vegetation in Chesapeake Bay and its Tidal Tributaries: 1971 to 1991
-------
Chesapeake Bay Program
------- |