US. ENVIRONMENTAL PROTECTION AGENCY
ounriMf\i
NUTRIENT TRANSPORT AND ACCOUNTABILITY
IN THE
LOWER SUSQUEHANNA RIVER BASIN
October 1974
Technical Report 60
Annapolis Field Office
Region III
Environmental Protection Agency
MIDDLE ATLANTIC REGION-III 6th and Walnut Streets, Philadelphia, Pennsylvania 19106
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EPA-903/9-74-014
Annapolis Field Office
Region III
Environmental Protection Agency
SUMMARY AND CONCLUSIONS
NUTRIENT TRANSPORT AND ACCOUNTABILITY
IN THE
LOWER SUSQUEHANNA RIVER BASIN
Technical Report 60
October 1974
Leo J. Clark
Victor Guide
Thomas H. Pheiffer
Annapolis Field Office Staff
Maryann L. Bonning Si grid R. Kayser
Tangie L. Brown Donald W. Lear, Jr.
Gerard W. Crutchley Evelyn P. McPherson
Daniel K. Donnelly James W. Marks
Gerard R. Donovan, Jr. Margaret S. Mason
Bettina B. Fletcher Margaret B. Munro
Margaret E. Flohr Marria L. O'Malley
Norman E. Fritsche Susan K. Smith
George H. Houghton Earl C. Staton
Patricia A. Johnson William M. Thomas, Jr.
Ronald Jones Robert L. Vallandingfiam
Orterio Villa, Jr,
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This report has been reviewed by EPA and approved for
publication. Approval does not signify that the contents
necessarily reflect the views and policies of the Environmental
Protection Agency, nor does the mention of trade names or
commercial products constitute endorsement or recommendation
for use.
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ABSTRACT
Identification of the Susquehanna River as the primary
I contributor of nutrients to the upper Chesapeake Bay and recognition
of the need to develop a nutrient management program for their mutual
protection, prompted the Annapolis Field Office, EPA, to conduct a
* one-year comprehensive nutrient survey in the lower Susquehanna River
Basin between Northumberland, Pa. and Conowingo, Md. Three distinct
hydrologic seasons were represented during the study period which
provided the foundation for an in-depth evaluation of all water quality
data obtained during this survey. Its principal objectives were:
A (1) quantitative identification of average nitrogen and phosphorus
* loadings and determination of seasonal variations in nutrient loadings
from every major sub-basin (2) delineation of point source and
non-point source nutrient contributions to establish effectiveness of
jj controllability measures (3) seasonal mass balance of nutrient
« loadings in the main stem and (4) determination of the fate of nutrients
in impounded areas. The report enumerates the important findings
T and conclusions which evolved during the intensive data analysis and
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interpretation and presents recommendations for future studies.
Hopefully, the material presented in this report can assist in the
implementation of a workable nutrient management program.
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Introduction
Possibly the most serious pollution problem currently plaguing
the upper Chesapeake Bay is one of progressive eutrophication
stemming from the uncontrolled discharge of nitrogen and phosphorus
in both the tidal and non-tidal areas of the major tributary
watersheds. Consequently, during 1969 the Annapolis Field Office
(AFO) embarked on a one-year monitoring study to (1) delineate
significant nutrient inputs to the Chesapeake Bay, (2) quantify
nutrient loadings and establish their seasonal trends, and
(3) determine the relative importance of each watershed's nutrient
load in affecting current biological conditions in the Bay. The
obvious conclusion from this study was the primary significance of
the Susquehanna River as a contributor of nitrogen and phosphorus to
the Chesapeake Bay, accounting for 50, 60 and 66 percent of the total
phosphorus, TKN and nitrate loadings, respectively, entering the Bay
on an annual basis.
Recognizing the dramatic effect of the Susquehanna River on the
water quality of the upper Chesapeake Bay and the need to develop a
nutrient management program for their mutual protection, AFO
initiated a comprehensive nutrient study in the lower Susquehanna
Basin between Northumberland, Pa., and Conowingo, Md. The study
was limited to this particular area since preliminary data analysis
revealed this lower reach to be the significant nutrient contributor
to the Bay. This twelve month study (June 1971 - May 1972), which
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comprised weekly or bi-weekly sampling at 37 stream stations and
monthly sampling of 25 major sewage treatment plant effluents, had
the following principal objectives:
a) quantitative identification of average nitrogen and
phosphorus loadings from every significant sub-basin in the lower
Susquehanna,
b) determination of seasonal variations in nutrient
loadings for individual sub-basins and their dependency on stream
flow,
c) delineation of point source and non-point source
nutrient contributions and determination of typical loading rates
from agricultural, forested and urban areas, especially the urban
Harrisburg metro area, in order to establish the potential
controllability of nutrients on a seasonal basis,
d) seasonal mass balance of nutrient loadings in the
Susquehanna River from the West Branch confluence to Conowingo, Md., and
e) determination of the fate of nutrients in impounded
areas along the lower Susquehanna River.
This report contains an enumeration of the important findings
which evolved during the course of data analysis and interpretation.
In addition, the report contains the most important conclusions
which can be drawn from the information presented followed by a
framework of recommendations for future studies. Graphical
supportive material is included in the Appendix.
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p It should be noted that Item 28 of the Summary and Item 23 of
§the Conclusion Sections of the report state the need for point source
control of phosphorus to protect the upper Chesapeake Bay from
ft excessive eutrophication. Conclusion 24 questions the effectiveness
of nitrogen control at point sources in the lower Susquehanna River
Basin in the absence of an accompanying reduction of the existing
nitrogen load from agricultural runoff. These findings and conclusions
were specifically developed in AFO Technical Report 56. Utilizing
ft a mathematical model and the data from Technical Report 60, the
combined impact of nutrient loadings from the Susquehanna River and
Baltimore, Maryland on the eutrophic condition of the upper Chesapeake
^ Bay was evaluated. Technical Report 56, "Nutrient Enrichment and
W Control Requirements in the Upper Chesapeake Bay, Summary and
ft Conclusions", should be read jointly with this report.
Technical Report 56 concluded that phosphorus could be made the
rate limiting nutrient in the upper Chesapeake Bay to control
A eutrophication or, specifically, the level of algal standing crop as
P measured by chlorophyll a_. For Susquehanna River flows less than or
A equal to 30,000 cubic feet per second (cfs), a reduction of 70 percent
in the existing point source phosphorus load from both the lower
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Susquehanna River and the Baltimore Metropolitan Area is required. At
higher river flows the phosphorus reduction at point sources increases
substantially. Point source control of nitrogen may not be a viable
alternative to phosphorus control during any flow condition at this
time without a substantial reduction in non-point sources of nitrogen.
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The Commonwealth of Pennsylvania has an adopted phosphorus
g policy for the lower Susquehanna Basin which requires at least 80
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percent removal of phosphorus from all new or modified wastewater
treatment facilities. Maryland places phosphorus limitations on
wastewater treatment facilities on a case by case basis in accordance
with receiving water characteristics. Even with the introduction of
point source phosphorus control in Maryland and Pennsylvania, the
impact from expected population growth in the study area will eventually
require serious consideration of non-point source control of nutrients
as a supplemental measure to high degrees of phosphorus and nitrogen
removal at point sources. Technological and cost considerations of
phosphorus removal and the relative magnitude of non-point source
nitrogen loads may make this consideration imperative. The delineation
and quantification of point source and non-point source nutrient
contributions for the lower Susquehanna Basin set forth in the
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report is substantial. It is hoped that management agencies will
utilize this body of data and expand upon it where necessary to develop
land-use management programs in conjunction with point source control
of nutrients to allow for the accomodation of future population
growth while at the same time maintaining permissable nutrient levels
in the lower Susquehanna Basin and the upper Chesapeake Bay.
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Summary
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1) The Susquehanna River between Sunbury, Pennsylvania
and Conowingo, Maryland, drains an area of approximately 9,000
square miles in south central Pennsylvania and contains a resident
population (1970 census) of approximately 875,000 (25% of the Basin's
total population).
2) In the lower Susquehanna River basin approximately 5%,
40%, 50% and 5% represents urban, agricultural, forested and other
areas, respectively.
3) Daily flows were monitored at Conowingo Dam during the
entire survey and ranged from about 4,200 cfs (Aug. 1971) to 319,000
cfs (Mar. 1972).
4) For purposes of data evaluation, the study period was
1
separated into three distinct seasons, each characterized by a
different but relatively uniform flow condition. The mean flows and
mean water temperatures for each season are shown in the table below:
Period
-
* June - Oct., 1971
Mean Flow
(cfs x 1000's)
11
37
88
Mean Water
Temperature
°C
23.5
3.6
12.5
Nov., 1971 - Feb., 1972
March - May, 1972
5) The average seasonal concentration of nutrients
measured near the mouths of the fourteen major tributaries of the
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lower Susquehanna River are presented as follows:
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The data shown in the preceeding tables indicate that Shamokin,
I Conoy, Codorus and Conestoga Creeks had the highest phosphorus
concentrations during each season. During low flow periods these
concentrations exceeded 1.0 mg/1 . Both total and inorganic
_ phosphorus concentrations usually decreased when stream flows
increased, indicating that excessive runoff was having a diluting
1| effect on point source discharges.
Maximum TKN concentrations (1.0 - 3.0 mg/1) were also measured
in Shamokin, Conoy, Codorus and Conestoga Creeks during the low
flow season and probably reflected the sizeable waste loadings
received by these streams. In general, TKN behaved similar to
phosphorus in that higher stream flows resulted in further dilution.
Oxidized inorganic nitrogen (N02 + N03) appeared to be the
most prevalent nutrient monitored. Because of the importance of
agricultural runoff, most streams did not experience the diluting
effect observed for other forms of nutrients during high flow
periods. Pequea Creek, a predominately agricultural watershed
having no significant point source discharges exhibited a high
NOp + NOg concentration but a relatively low TKN concentration for
each season. Stony Creek, a predominately forested watershed, on
the other hand, contained relatively low nutrient concentrations
regardless of season.
Except for Shamokin Creek, a highly acidic stream where
nitrification is probably inhibited, ammonia levels were quite low,
especially during the warmer periods when the nitrification reaction
should be most pronounced.
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6) The average seasonal nutrient concentrations measured
I at the ten main stem Susquehanna stations are presented in the tables
on the following pages.
| Since the volume of flow in the Susquehanna is extremely
M large in comparison to the tributary flows, the river was not very
responsive to a given nutrient input in terms of a concentration
increase. The considerable amount of dilution present is illustrated
in the comparatively low phosphorus and nitrogen concentrations
l| shown in the following tables. Phosphorus concentrations were
M generally higher during the low flow periods but did not exceed 0.3
* mg/1. Moreover, concentrations were consistently greater in the reach
4 from Harrisburg to Conowingo than they were in the upper reach,
probably the result of several large tributary inputs. The fairly high
phosphorus concentrations observed in the vicinity of Harrisburg during
the high flow period may be partially due to combined sewer overflows.
It is also important to recognize the dramatic decrease in phosphorus
during lower flow periods in the area of Conowingo and to a lesser extent
at Safe Harbor. These impoundments appeared to represent a significant
"sink" for phosphorus when detention times were long.
The maximum TKN and N09 + NOo concentrations (0.82 mg/1 and
2
1.3 mg/1, respectively) were measured in the Susquehanna River between
Safe Harbor and Conowingo Dams. While TKN was always greatest during
low flow periods because of minimal dilution of tributary inflows,
I NOo + NOg levels were greater during the higher flow-lower temperature
periods. This latter relationship reflected the effects of runoff
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from agricultural land and reduced biological utilization rates.
The Susquehanna River water appeared to be highly nitrified during
high temperature periods as evidenced by the extremely low NH~
concentrations. During low temperature periods, however, NFL was
generally more abundant because of reduced nitrification and
biological utilization rates.
7) In an attempt to establish statistically valid relation-
ships between both nutrient concentrations and nutrient loadings
versus stream flow, a series of regression analyses utilizing the
appropriate sampling data were performed at each station and for
each parameter. These regression analyses were made using both
linear and log transforms with the latter yielding the best correlation,
A summary of the regression data for nutrient concentrations
versus stream flow is presented in the following table. As can be
seen, numerous regressions resulted in poor correlation based upon
non-significant "t" statistics at the 5 percent level. However,
several interesting conclusions can be drawn from the remaining
data. In the case of total phosphorus, negative slopes ranging
from about 0.2 to 0.6 were detected excepting for Pequea Creek.
This would corroborate the previous discussion wherein a diluting
I effect was shown to occur at higher flow conditions. Moreover,
these negative slopes would imply that the majority of phosphorus
was contributed by wastewater discharges. Pequea Creek, on the
other hand, had a large positive slope (0.97) indicating that land
I
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runoff may be the primary source of phosphorus in that watershed.
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The relatively large negative slopes of the TKN regression
equations indicated that Shamokin, Codorus and Conestoga Creeks all
received major TKN loads from wastewater discharges. Shamokin
9 Creek, an acid stream receiving a considerable quantity of untreated
sewage, exhibited a particularly large negative slope (-0.92). At
the other end of the spectrum were streams having relatively minor
point source contributions, i.e. Pequea and Yellow Breeches Creeks,
which showed highly positive slopes (0.78 and 0.67). The remainder
of the streams appeared to be influenced by a combination of point
and non-point sources insofar as TKN was concerned.
All of the sub-basin sampling stations where statistical
validity was realized had a positive relationship between
N00 + NO, and stream flow. The slopes varied from about 0.2 to over
12 3
1.0. The consistency of this relationship indicated the significant
u overall effect of agricultural runoff as a contributor of nitrate
nitrogen especially during periods of intense runoff.
8) The main stem Susquehanna River sampling results should
theoretically reflect the accumulative effect of all tributary
| inputs. Regression data obtained for a nutrient concentration versus
stream flow relationship for the Susquehanna, which are summarized
in the following table, basically substantiated this contention.
flj In the case of phosphorus and TKN, the slope terms were very
similar for every station where statistically valid data were
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realized. The range for phosphorus (-0.20 to +0.12) was somewhat
lower than the values recorded for the tributary stations since the
effects of land runoff, including drainage along the river itself,
I were more pronounced in comparison to point source discharges. A
similar situation was indicated by the generally greater positive
relationship between nitrate nitrogen and stream flow for the
Susquehanna River. The range in slopes for TKN (-0.32 to -0.05)
suggested a net diluting effect when compared to all of the tributary
I data presented previously. The negative relationships for
phosphorus and TKN concentrations versus stream flow and the
I positive relationships for nitrate nitrogen versus stream flow
determined for the main stem Susquehanna River were essentially in
agreement with those reported for the Potomac River.*
I 9) Regression analyses proved much more statistically
reliable when nutrient loadings and stream flow relationships were
W investigated. The average nutrient loadings computed for the various
j tributaries to the Susquehanna River from regression data are presented
in the following tables for each of the three hydrologic seasons. It
should be noted that average stream flows for the entire season were
used, when available, rather than flows corresponding to individual
| sampling days.
The watersheds contributing the greatest phosphorus loads
regardless of season were Conestoga and Codorus Creeks and the Juniata
River. The major nitrogen contributing watersheds were Conestoga and
Swatara Creeks and the Juniata River. The Juniata River was a
* * Nutrients in the Upper Potomac River Basin, Jaworski , CTSL Technical
Report 15, August, 1969.
-------
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_
19
significant contributor of nutrients due to its relatively large
flow whereas the other streams contained considerably greater
I nutrient concentrations because of sizeable inputs from wastewater
effluents and land runoff.
10) Average seasonal nutrient loadings computed at each of
the main stem Susquehanna River stations from regression analysis and
average stream flow data are shown in the following tables. A
graphical mass balance analysis of these loadings will be presented
and discussed in a subsequent section of this report.
I Both nitrogen and phosphorus loadings throughout the lower
Susquehanna River varied drastically from one season to the next
because of differences in stream flow. The loadings also showed a
gradual but steady increase in the downstream direction which reflected
substantial inputs from several tributary watersheds. It is important
I to note that generally about 30-40 percent of the total phosphorus
M load was inorganic, regardless of spatial or temporal position. In-
organic nitrogen accounted for about 50, 65 and 80 percent of the
total nitrogen load during low, mean and high flow periods,
respectively. This upward shift was partly due to relatively greater
P increases in nitrate rather than organic nitrogen loadings from major
tributary watersheds during periods of excessive runoff.
The nitrogen-phosphorus ratio (by atoms) throughout the lower
B Susquehanna River averaged about 34:1 during the summer season, 46:1
in the winter and 43:1 in the spring. These values are considerably
greater than the elemental ratios comprising algal cellular material
_ (15-20:1) reported in the literature.
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11) The following table shows the average daily phosphorus
and nitrogen loads currently discharged by each of the major wastewater
I treatment facilities in the lower Susquehanna Basin. Also shown are
the average per capita loadings based upon the present population
| served. The three areas responsible for approximately one half of the
_ total measured phosphorus and nitrogen load from municipal point source
discharges were Harrisburg, Lancaster and York.
Utilizing the average per capita loadings (0.024 Ibs/day TPO, and
0.018 Ibs/day TKN) and the entire lower basin population served by
sewerage facilities (850,000), the estimated total phosphorus and
_ nitrogen contributions from wastewater effluents were computed to be
' 20,400 Ibs/day and 15,300 Ibs/day, respectively.
12) The average daily phosphorus and nitrogen loadings
discharged by the major water using industries in the lower Susquehanna
River Basin are presented following the municipal wastewater table.
These data were contained in the industries' NPDES permit applications
^ and reflect the best currently available information on loading rates.
While the list is probably not complete, it is believed that the
industries shown in the following table constitute the bulk of the
industrial nutrient contribution based upon a comprehensive compilation
of industrial discharges throughout the Susquehanna Basin.
As can be seen, the total phosphorus and nitrogen loads from
industrial point-source discharges were estimated to be 1,355 Ibs/day
and 4,800 Ibs/day, respectively. Of the total nitrogen load
approximately 40 percent was in the form of TKN and 80 percent was as
inorganic nitrogen (NH3 + N0? + NO-J.
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30
13) To assist in the annual nutrient budget evaluation, it
was necessary to ascertain a breakdown of land usage for the entire
lower Basin. Presented in the table on the following page is a
| delineation of land usage for the various tributary watersheds of the
Susquehanna River for the three major land use categories, namely
agricultural (cropland and pasture), forested and urban.
V 14) In order to estimate typical nutrient yields from the
two major land use areas within the Susquehanna River Basin (i.e.
I'
agricultural and forested), analyses of survey data from
_ representative watersheds were performed. Using the Pequea Creek water-
* shed as primarily agricultural and the Stony Creek watershed as
tf forested, the effect of land use on both nutrient concentrations and
loadings in these surface waters could be evaluated. These data were
then extrapolated to develop estimates of the nitrogen and phosphorus
yields (lbs/day/mi2) for application to other agricultural and
forested areas within the Susquehanna Basin.
Total phosphorus, total Kjeldahl nitrogen and nitrite-nitrate
nitrogen contributions measured in these selected watersheds during each
season are presented in the following tables. As can be seen, a
considerable difference existed between the concentration and loading
rates of all three parameters. Excepting for TKN, the agricultural
runoff rates were at least an order of magnitude greater than
corresponding rates for forested areas. The extremely high N0? + NCU
concentrations (4.0 - 5.7 mg/1) characterizing the Pequea Creek water-
shed revealed the high mobility of the N0q ion, especially during
I
w periods having excessive runoff.
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35
15) The City of Harrisburg has been reported to have over
20 combined sewer outfalls which discharge large quantities of sanitary
waste and street surface runoff directly to the Susquehanna River
during periods of heavy rainfall. The effects of these discharges
coupled with other urban runoff from the Harrisburg metro area were
estimated from an examination of the measured nutrient loads in the
Susquehanna River at both the Route 15 and the 1-83 Bridge stations.
As will be shown in a later section of this report (mass balance
analysis), considerable increases in the total phosphorus and
nitrogen loads were observed in the vicinity of Harrisburg during the
high flow season. Since the Susquehanna River received no major
wastewater effluents from the confluence of Conodoguinet Creek to the
1-83 Bridge it was assumed that these differences in loading could be
attributable to the collective effects of urban runoff (point source
and non-point source).
Allowing for the possibility of nutrient re-introduction into
the water column through the scouring of bottom sediment and the
innundation of shoreline weeds and other sources which are apparent
during the high flow periods, it appeared that approximately
6,000 Ibs/day of total phosphorus and 14,000 Ibs/day of total nitrogen
(approximately 2/3 of which was T.KN) were contributed by the entire
Harrisburg urban area during the maximum flow period of March-May 1972.
These figures completely overshadowed the average contributions from
the area's wastewater facilities.
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During the mean flow period (Nov. 1971 - Feb. 1972) respective
phosphorus and nitrogen contributions from the Harrisburg metro area
exclusive of wastewater effluents were estimated to be 800 Ibs/day
9 and 3,700 Ibs/day (approximately 2/3 of which was TKN). During the
A low flow period no measurable contribution was detected.
16) In view of the fact that nutrient loads in the
Susquehanna River above and below the Harrisburg area indicated an
extremely large urban input, the magnitude of which may be somewhat
questionable and probably not applicable to other urban areas in the
jg Basin, the decision was made to utilize relevant literature material
to provide independent estimates of typical area! nutrient loading
rates exclusive of untreated sanitary sewage contributions. These
estimated rates were intended to serve as a basis for developing a
total urban effect on the nutrient balance in the lower Susquehanna
« Basin.
A summary of the relevant literature data which was used as
I a basis for estimating the nutrient loading rates for the urban and
suburban portions of the Susquehanna River Basin are presented in
the following table.
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17) Based on a review of the aforementioned nutrient
data summary for storm water, the decision was made to use the
following loading rates applicable to city and suburban areas of
the Susquehanna Basin for the high flow season. It may be noted
that maximum importance was attached to the recent estimates of
urban contributions such as the data presented in EPA's "Water
Pollution Aspects of Street Surface Contaminants", and AFO's
Technical Report No. 35.
I
B Areal Nutrient Loads
_ Urban Runoff (Storm Water)
* (Ibs/mi2/day)
1 T.POu TKN N0.3
City 20 30 15
Suburbs 10 15 10
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40
Utilizing the above nutrient loading rates for the major
cities and suburban areas of the lower Susquehanna Basin, the
total non-point source urban runoff nutrient contributions to the
Susquehanna River for the high flow season were determined and
are contained in the table below:
Urban Runoff Contributions
Lower Susquehanna River Basin
(High Flow Season: Mar. 1972 - May 1972)
Urban
Location Land T.PO. TKN N02+N03
Area
(mi2) Ib/mi2/day Ib/day Ib/mi2/day Ib/day Ib/mi2/day
Harrisburg 7.6 20 152 30 228 15
Lancaster 7.2 20 144 30 216 15
Lebanon 4.6 20 92 30 138 15
York 5.3 20 106 30 159 15
Urban Area
exclusive
of Major
Cities 425.3 10 4253 15 6380 10
Total
Urban
Area 450 4750 7120
Applying the measured percentage increase in phosphorus and
nitrogen urban loadings between the Rt. 15 and Rt. 83 Bridge stations
during the middle and high flow periods (see statement #15), an
Ib/day
114
108
69
80
4253
4625
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41
estimated urban runoff nutrient contribution for the middle flow
period was determined.
The non-point source urban nutrient loadings (Ibs/day) and
average urban nutrient loading rates (Ibs/mi2/day) for the lower
Susquehanna River Basin during the middle flow season are presented
as follows:
Urban Runoff Contributions
Lower Susquehanna River Basin
(Middle Flow Period: November 1971 - February 1972)
Urban
Location Land Area T.P04 TKN N02 +
mi2 lb/day/mi2 Ib/day lb/day/mi2 Ib/day lb/day/mi2
Harrisburg 7.6 2.6 20 7.8 60 3.9
Lancaster 7.2 2.6 19 7.8 56 3.9
Lebanon 4.6 2.6 12 7.8 36 3.9
York 5.3 2.6 14 7.8 41 3.9
Urban Areas
exclusive
of Major
Cities 425.3 1.3 553 3.9 1659 2.6
Total 450 608 1852
It was assumed that urban runoff contributions for the low flow
season were negligible and consequently were not considered in the
mass balance analyses.
N03
Ib/day
30
28
18
21
1106
1203
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42
* 18) Utilizing the nutrient loading rates for urban runoff
flj presented in statement 16 and typical population densities for
large metropolitan areas in the Susquehanna Basin, i.e. Harrisburg,
| York and Lancaster, as well as outlying suburban areas (see table
H in Appendix), an attempt was made to estimate total nitrogen and
phosphorus contributions assuming various percentages of sanitary
I sewage overflows. The graphs in the Appendix depict these
contributions which should be applicable to a variety of situations
J where combined sewer overflows are a problem. The component
_ representing sanitary sewage (see table below) was derived from the
per capita loading rates presented in statement 11.
I Areal Nutrient Loads
Sanitary Sewage
(Ibs/mi2/day)
City 225 162 0
| Suburbs 75 54 0
« Unfortunately, the actual quantities of untreated sanitary
* sewage which are bypassed during different storm intensities have
not been defined for either Harrisburg, York or Lancaster. However,
based upon the measured increased in nitrogen and phosphorus loadings
p in the Susquehanna River at Harrisburg, it would appear that a
« relatively large fraction of the wastewater generated in the area is
* transported through the combined sewer system, especially during the
M high flow season.
I
T.P04 TKN
-------
-------
I
19) Applying the nutrient loading rates developed in
statement #14 for agricultural and forested land to the total
22
agricultural (3600 mi ) and forested (4500 mi ) areas of the lower
| Susquehanna River Basin, relative contributions of T.PO., TKN and
|N09 + N07 in pounds per day were determined. Inclusion of the total
2 6
urban nutrient contributions as developed in statement #17 results
fl in the following tables which show the estimated seasonal nutrient
loadings in the Susquehanna River Basin for every major land-use
J§ category.
Although the total forested area exceeds the agricultural area
in the Basin, the latter represented the principal land use
contributor of T.PO., TKN and NO., (especially during the high flow
season). In addition, the urban contribution of nutrients is
£ significant during the high flow season in comparison with other
land uses even though the urban area comprises only about 5% of the
entire basin.
The key non-point source nutrient input to the lower
Susquehanna River Basin is definitely from agricultural runoff with
significant periodic augmentation by urban stormwater runoff and
^ combined sewer overflows from the major metropolitan areas.
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47
I 20) The average seasonal nutrient loadings attributed to
_ land runoff (non-point sources) and the average annual nutrient
loadings attributed to municipal and industrial wastewater
discharges (point sources) are summarized as follows:
I
NUTRIENT LOADINGS
I IN THE
LOWER SUSQUEHANNA RIVER BASIN
I
I
Point Source* , Non_Point source Contributions , Total (Point + Non-Point Sources
Contributions
(Municipal ; -
Parameter Wastewater & June 1971 Nov. 1971 Mar. 1971 June 1971 Nov. 1971 Mar. 1972
Industrial to to to to to to
Discharges) Oct. 1971 Feb. 1972 May 1972 Oct. 1971 Feb. 1972 May 1972
I Ibs/day j
i
- » -
IT.POij as
PO^ 21,800 8,400 20,000 31,300 30,000 42,000 53,000
JTKN as N 17,400 14,000 35,000 54,000 31,500 53,500 71,500
as N 20,100 106,000 198,000 264,000 126,000 218,000 284,000
I
I
* Average annual load applicable to each season
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48
a) Of tKe total phosphorus and nitrogen loadings from
the lower Susquehanna River Basin the percentages attributable
to point source and non-point source discharges are as follows:
1
Parameter
June 1971 - Oct. 1971
; Point Source Source"1
Nov. 1971 - Feb. 19
Point Source N°^
72 JMar. 1972 - May 1972
^nt:! Point Source |N^nt
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T.PO^ as
TKN as N
TN as N
PO
72
55
16
28
45
84
52
33
48
67
91
41
24
59
76
93
As can be seen, non-point source contributions of T.P04 and
TKN predominate when flows increase. Total nitrogen contributions
from non-point sources are most significant in every season. These
differences in percentage signify the increased importance of the
collective load from non-point sources when runoff rates are high.
During the high flow period (March - May 1972) approximately
93 percent of the estimated 284,000 Ibs/day of total nitrogen
(N02 + N03 and TKN) entering the surface waters of the lower basin
was from land runoff (non-point sources) with the remaining 7 percent
from municipal wastewater and industrial discharges (point sources).
-------
49
Of the 264,000 Ibs/day of total nitrogen from land runoff,
approximately 229,000 Ibs/day, or 87%, was from agricultural land
areas which comprise only 42% of the total drainage area in the
I lower basin.
b) The average annual yield, Ibs/day/sq. mile, for
each season based on 8,550 square miles in the lower Susquehanna
River Basin (3600 mi2 - agriculture, 4500 mi2 - forest and 450 mi2
B urban) is as follows:
I
m Average Annual Nutrient Yield
(Point + Non-Point Sources)
Ibs/day/sq. mile
Parameter ' June - Oct. 1971 ;Nov. 1971 - Feb. 1972 !Mar. 1972 - May 1972
T.PO,, as P04 3.5 | 4.9 6.2
TKN as N 3.7 6.3 : 8.4
N02N03 as N 11.1 19.3 24.9
TN as N 14.7 25.5 33.2
I
I =
Thus, the average annual yield was directly related to the
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runoff rates.
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I
21) An attempt was made to mass balance the average
I seasonal phosphorus and nitrogen loads (TPO., TKN and NCL+NO.,)
in each of the tributary basins. The method employed for this
H analysis was to compare measured loads with expected loads in
accordance with the following equation (Total Phosphorus):
50
I
Pt = Pw * Pa * Pf + Pu t Ps
Where:
P. = total measured phosphorus in watershed
P = phosphorus in wastewater discharges
P = phosphorus from agricultural land
a
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Pf = phosphorus from forested land
P = phosphorus from urban runoff
P = phosphorus lost or released in the stream channel
I through biological utilization, deposition, scouring, etc,
Of particular importance in this analysis is the magnitude and
I sign of the P term. The following tables, which delineate the
_ various components of the mass balance equations, permit several
conclusions to be drawn regarding P (or TKN and NO depending on
j o o
the parameter).
The negative signs shown for most of the P terms, regardless
of flow, indicate that phosphorus was being retained in the stream
channels, bound there by sediments and/or aquatic plants. The
apparent loss of nitrogen fractions which prevailed during the low
flow period might be temporary, however, as indicated by the
increased number of positive TKN and NO terms during flood flow
I
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51
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conditions when a considerable tonnage of sediment is known to be
I transported to the main stem of the Susquehanna River. An
explanation of why nitrogen and phosphorus recoverability differ so
greatly during periods of high streamflow and extensive scouring
within these tributary basins may be due to the high solubility of
nitrogen - especially the nitrate form.
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22) A seasonal mass balance analysis for the main stem
Susquehanna River between Northumberland, Pa., and Conowingo Dam,
Md. was performed based upon all of the regression data previously
presented. The graphs in the Appendix vividly depict the relative
effects of each tributary's load and the Harrisburg metro area on
the phosphorus and nitrogen balances in the river. In addition,
changes in mass between tributary confluences resulting from
m various physical, chemical and biological reactions occurring
within the stream channel are illustrated. The following
observations are noteworthy:
a) The impoundments along the lower Susquehanna,
especially Conowingo Dam, had a profound effect on the phosphorus
M load in the river during the low flow periods. As can be seen,
the load decreased from about 17,000 Ibs/day to 9,000 Ibs/day
between Columbia and Conowingo. During high flow-low temperature
periods this decrease diminished because of the reduced rates of
biological utilization and shorter retention times in the impoundments,
§b) During the high flow period a considerable increase
in phosphorus (20,000 Ibs/day) was detected between Penns Creek
V and the Juniata River. Since this area is primarily undeveloped
with the total phosphorus contribution from existing land usage
estimated to be less than 2,000 Ibs/day, it was assumed that scouring
of the bottom sediment and inundation of shoreline marsh and weeds
played an important role in the phosphorus balance. The Susquehanna
channel is very unique in that its width undergoes a much greater
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62
increase than its depth when flows rise. It is also a known fact
that aquatic weeds and other sources of nutrients are prevalent
along the river's shore.
Allowing for contributions from land runoff, it was estimated
that about 500 Ibs/day/mile of total phosphorus (as PO.) was
J introduced into this reach of the Susquehanna River during the
maximum flow period. During the mean flow period (Nov., 1971 -
Feb., 1972) this overall scouring rate was computed to be
approximately 70 Ibs/day/mile.
c) A comparison of wastewater effluents and other urban
9 contributions of phosphorus in the Harrisburg metro area revealed
the significance of the sewage treatment plants during low-flow
periods and the over-shadowing of this load by non-point source
loads during high flow periods.
d) Total nitrogen behaved much more conservatively in
y the Susquehanna River than phosphorus, particularly in the area
§of major impoundments. While the phosphorus load was reduced
radically through the impoundments, nitrogen remained essentially
V unchanged regardless of flow.
e) The relative importance of point source and non-
P point source contributions of total nitrogen from the Harrisburg
§area for various flow conditions closely paralleled the findings
presented in the above statement for phosphorus.
M f) Due to excessive stratification it was not possible
to adequately balance the summation of the North Branch and West
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63
Branch nitrogen load with the measured load at Sunbury. This
problem became especially acute during the high flow period when
about 25,000 Ibs/day of TKN could not be accounted f0r\
I g) The effects of scouring and inundation of shoreline
vegetation were not restricted to phosphorus. A review of the
nitrogen data between Penns Creek and the Juniata River indicated
a significant increase in load during high flow periods (60,000
Ibs/day) which corresponded closely to the phosphorus profile and
which could not be attributable to normal runoff from the area.
Deducting the appropriate agricultural and forested runoff loads
m from this observed increase yielded a scouring rate of 1,200
Ibs/day/mile. A rate of about 100 Ibs/day/mile was computed for
the mean flow condition. During low flow - high temperature periods
both nitrogen and phosphorus loadings were reduced in this stream
reach probably because of a physical deposition process.
| h) The mass balance analysis of the nitrogen fractions
H (TKN and NO.,) generally corroborated the pertinent findings for
total nitrogen. During the low flow period the ratio of TKN to NO.,
IT varied from about 2:1 in the extreme upper reach of the Susquehanna
River to about 1:1 near Conowingo. This increased abundance of nitrate
£ nitrogen may be partly due to nitrification and, more importantly,
I to the relatively greater nitrate loadings contributed by the
various sub-basins. A similar pattern was evidenced during the
I mean flow condition when nitrification was minimal.
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* 65
I
transported by the Susquehanna River, it has been estimated that
P only about 2 million tons actually enters the Chesapeake Bay
_ because much sediment is trapped behind the power dams along the
* lower Susquehanna.
25) A summary of annual sediment yields and computed
nutrient yields for a comparable time period are presented in the
following table for eight stations throughout the lower
Susquehanna River Basin. Except for Conestoga Creek, the data
revealed a definite relationship between the tons per square mile
of sediment yield and the phosphorus yield (lbs/mi2) on an annual
basis. The annual TKN yield also appeared to be strongly influenced
by sediment load. The leaching and general mobility characteristics
of the NCu ion in soil are such that a reliable correlation between
I
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26) Regression analyses performed separately with 1969
(Chesapeake Bay Nutrient Input Study, TR #47) and
nitrogen and phosphorus data at the Conowingo Dam
distinct increases in loading for both parameters
year period. A comparison of these Susquehanna 1
follows:
Flow Total Phosphorus
(cfs) (Ibs/day)
1969 1971
10,000 6,500 8,500 75
50,000 60,000 75,000 370
100,000 150,000 190,000 750
27) The data presented in the following
1971 total
station revealed
during the two
oadings is as
Total Nitrogen
(Ibs/day)
1969 1971
,000 82,000
,000 420,000
,000 850,000
table, which were
derived from a mass balance analysis, depict the effects of
different reductions at all continuous point source discharges on
the river loadings at Conowingo Dam and reveal the extent of
nitrogen and phosphorus controllability during di
and flow conditions.
fferent seasons
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64
i) As the flows increased, differences in the TKN and
NCL loadings became less pronounced. Moreover, at times of excessive
stream flow these loadings approached their maximum level much
farther upstream.
23) The effects of sediments on the concentration of
nutrients in surface waters as summarized by Jaworski in AFO
Technical Report #15 are as follows: (1) sediments contain nutrients
and act as transport mechanisms (2) due to the adsorption phenomena
sediments when deposited in the stream channel also trap nutrients
(3) more than 99% of the soluble nitrogen is in the form of nitrates
m which leach at a more rapid rate than the other forms of nitrogen, and
tt (4) in contrast to the high mobility of nitrate nitrogen, phosphorus
compounds react vigorously with soil and have a very low mobility.
24) Sediment yields calculated by USGS at over 40 sites
throughout the Susquehanna Basin generally indicated that the
seasonal distribution of sediment discharge is quite similar to that
of water discharge. Moreover, the long-term data showed the annual
sediment discharge rates to the extremely variable but strongly
related to a particular year's hydrograph. On the average, the
Susquehanna River transports approximately 3 million tons of
sediment annually which equates to 110 tons per square mile. Extreme
sediment yields vary from 20 tons per square mile in established
forest land to 800 tons per square mile in denuded areas and areas
disturbed by strip mining. Of the three million tons of sediment
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69
28) In order to protect the upper Chesapeake Bay from
excessive eutrophication, a combination of mathematical modeling
I studies and mass balance analyses have indicated that during
relatively low-flow conditions (<_ 30,000 cfs), 70-75 percent of
I the total phosphorus load from point source discharges in the lower
_ Susquehanna Basin must be eliminated. For a river flow of 50,000
cfs, a 90 percent reduction of the point source contribution must
be realized.
29) Based on the extensive body of data previously
presented in this report nitrogen is largely uncontrollable in the
Susquehanna Basin, especially during periods when flows and runoff
V rates are high. In order for the management of nitrogen to be a
viable alternative during extremely low-flow periods (_< 10,000 cfs)
about 90 percent of the point source loading will have to be
fl eliminated. In view of the importance of agricultural runoff as
a contributor of nitrogen, and to a lesser extent phosphorus, it
is recommended that methods be devised and seriously considered to
maximize control of this once regarded non-controllable source of
nutrients.
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70
Conclusions
1) The tributary streams of the lower Susquehanna River
which had the highest phosphorus concentrations on both an annual
and seasonal basis were:
Shamokin Creek
Conoy Creek
V Codorus Creek
Conestoga Creek
g 2) The greatest total nitrogen concentrations both seasonally
_ and annually, were measured in the following tributaries:
* Conoy Creek
fl Chickies Creek
Conestoga Creek
Pequea Creek
3) Maximum nitrogen and phosphorus concentrations in the
M tributary streams occurred during the low flow period with the
m exception of oxidized inorganic nitrogen, the most abundant nutrient
fraction in the study area. Higher stream flows appeared to have
ff a "diluting" effect on the TKN and phosphorus concentrations but
not on the oxidized nitrogen fraction.
J| 4) In general, all seasonal concentrations of every nitrogen
_ and phosphorus fraction in the Susquehanna River were dramatically
higher in the reach from Harrisburg to Conowingo Dam than in the
reach upstream of Harrisburg.
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71
0 5) The major impoundments along the lower Susquehanna River,
M i.e. Conowingo and Safe Harbor, represented a significant "sink"
for phosphorus, particularly during low flow periods when
detention times were long.
6) Phosphorus concentrations in the Susquehanna River were
not significantly influenced by variations in stream flow as were
the nitrogen fractions. While TKN concentrations throughout the
I Susquehanna River were at a maximum during the low flow - high
temperature season, NOp+NO^ levels increased during higher flow -
lower temperature periods due to amplified effects of agricultural
I runoff and reduced biological activity.
7) The major phosphorus contributing streams, in terms of
| daily loads to the Susquehanna River, were as follows:
Conestoga Creek
Codorus Creek
Juniata River
8) Streams providing the major daily loads of nitrogen were
I as follows:
Conestoga Creek
0 Swatara Creek
Juniata River
9) Nitrogen-phosphorus ratios (by atoms) in the lower
I Susquehanna River varied from about 34:1 to 46:1. Approximately
30-40 percent of the total phosphorus load represented the inorganic
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72
fraction, whereas approximately 50-80 percent of the total nitrogen
load represented the inorganic fraction.
10) The total nitrogen and phosphorus contributions from
municipal wastewater effluents were estimated to be about 15,000
I Ibs/day (5 to 25 percent of the maximum measured load in the
Susquehanna River) and 20,000 Ibs/day (40 to 200 percent of the
maximum measured load in the river), respectively.
11) Approximately 50 percent of the total measured phosphorus
and nitrogen load from municipal wastewater effluents was contributed
from three areas - Harrisburg, Lancaster and York.
12) The total nitrogen and phosphorus contributions from major
| industrial dischargers in the lower Susquehanna River Basin were
' estimated to be approximately 4800 Ibs/day (30% of the municipal
wastewater load) and 1350 Ibs/day (7% of the municipal wastewater
load), respectively.
13) Runoff from agricultural land (42 percent of the study
area), accounted for 75-85 percent of the non-point source phosphorus
contribution, 60-70 percent of the TKN contribution, and more than
90 percent of the nitrate nitrogen contribution from all non-point
jl sources.
14) Runoff from forested land (53 percent of the study area),
I accounted for 10-15 percent of the non-point source phosphorus
load, 25-30 percent of the TKN load, and about 5 percent of the
nitrate nitrogen load from all non-point sources.
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73
15) During the high flow period, it has been estimated that
urban storm water from a 450 square mile area accounted for about
15 percent of the non-point source phosphorus load, 13 percent of
the TKN load, and a negligible percentage of the nitrate nitrogen
load from all non-point sources.
| 16) Although the nutrient contribution from the numerous combined
_ sewer outfalls in Harrisburg was not accurately quantified, it
appeared, from a comparison of sampling data obtained above and
below the majority of these sewers, that this source was quite
significant, actually surpassing the measured nitrogen and
I phosphorus load from the Harrisburg S.T.P. during the peak flow
season.
17) During the low flow season, wastewater effluents alone
accounted for 16 and 72 percent of the total nitrogen and
phosphorus contribution from both point and non-point sources,
I respectively. During the high flow condition, these percentages
decreased to about 7 and 40 percent, respectively.
18) A mass balance analysis of the data collected in the
tributary watersheds indicated that a significant quantity of
phosphorus was retained in the stream channels through a deposition
or biological utilization process during every flow season. While
nitrogen showed similar loses during the low flow season, its
recoverability during the higher flow periods, when scouring of
the bottom sediment prevails, appeared to be greater and more
widespread than phosphorus.
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19) A mass balance analysis of the main stem Susquehanna River
data, besides underscoring the importance of major impoundments as a
sink for phosphorus, depicted a substantial introduction of both
because of scouring of the bottom sediments and innundation of
shoreline vegetation. Any apparent difference in scouring characteristics
of the main stem Susquehanna River and the tributary streams as related
to phosphorus may be the result of higher stream velocities in the river,
longer duration of high flows, sediment content and its adsorption
potential, or some other complex physical behavior. During the low
flow period deposition of nutrients and biological utilization by
aquatic plants were significant in-stream processes implied by mass
balance data.
2
20) The areal yields of phosphorus and TKN (Ibs/mi ) appeared
2
to be markedly influenced by sediment yields (tons/mi ) based upon
nitrogen and phosphorus into the water column during high flow periods
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average annual data collected by USGS at eight stations in the lower
I Susquehanna Basin. Such a relationship could not be established for NO.,.
21) A regression analysis utilizing 1969 and 1971 nutrient data
| collected at Conowingo Dam revealed that distinct increases in both
_ phosphorus and nitrogen loadings for comparable stream-flows have
occurred during this two year period.
22) Phosphorus is considerably more manageable than nitrogen in
the lower Susquehanna River Basin during all flow conditions.
23) In order to protect the biological integrity of the upper
Chesapeake Bay, a sizeable reduction (70-90 percent) in the existing
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point source contribution of phosphorus must be realized.
I 24) The effectiveness of nitrogen control at point sources is
questionable unless attention is given towards reducing the existing
load from agricultural runoff.
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RECOMMENDED FUTURE STUDIES
1. Select a primarily agricultural watershed to study fertilizer
application practices. This study should include but not be limited
to the following: determination of the present rate of application
(Ibs/acre) and types of fertilizer applied (quick vs. slow release);
quantification of seasonal application practices (fall, summer and
spring); identification of the state of the plant growth that
fertilizers are applied. Study results would be compared to recommended
Federal and State fertilizer application programs to determine if the
existing practices of the farmers within the watershed are sound, both
in terms of conservation and economics. Should it be found that
excessive amounts of fertilizer are being applied, economic
considerations should dictate reassessment of current practices.
Subsequent to the implementation of any modified fertilization program
water quality monitoring of the watershed would allow for data
comparison with previous studies (Technical Report 60) to show possible
nutrient reductions in the watershed.
2. Technical Report 60 concluded that the area! yields of
2
phosphorus and TKN (Ibs/mi ) appeared to be markedly influenced by
2
sediment yields (tons/mi ) based upon average annual data collected by
the USGS at eight stations in the lower Susquehanna Basin. Actual
nutrient loadings associated with sediment yields, however, were
not determined. It is recommended that a study be undertaken to
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contrast a watershed farmed with a high degree of conservation measures
g employed versus a watershed in which conservation practices are
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minimal. Area! sediment yields from the two watersheds would be
determined on a seasonal basis. The phosphorus content of the
sediment would be determined in order to establish the relative
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contribution of phosphorus from the erosion of farmland under the two
contrasting situations. The selection of phosphorus for this study
seems appropriate because of its correlation with sediment yields
(Technical Report 60) and its known adsorption to sediment particles.
In addition, reduction of non-point source phosphorus input by erosion
control measures in conjunction with direct point source control of
phosphorus should enhance the possibilities of making phosphorus the
rate limiting nutrient to control eutrophication in impoundments in
J the lower Susquehanna Basin and the upper Chesapeake Bay.
_ 3. The significance of the construction industry as a non-point
source of pollutants in the lower Susquehanna Basin should be examined.
The scope of Technical Report 60 did not include the assessment of
nutrient contributions from specific land uses. The impact of sediment
loading from activities including, but not limited to, housing
construction, commercial building, road construction, and water
I resources projects should be evaluated for the purpose of developing
guidelines for erosion and sediment control for use by the various
management agencies.
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4. Although the nutrient contribution from the numerous combined
sewer outfalls in the City of Harrisburg was not accurately quantified
in Technical Report 60, the significance of the combined sewer system as
a major source of nitrogen and phosphorus was established. Studies
should be carried out to determine the sources of nitrogen and
phosphorus in the urban runoff. The relative contribution from
diffuse sources such as street debris, rainfall, snow melt, lawn
fertilizer, vegetative decay, and fallout from particulate matter
should be included in a study of this nature. The object of the
study would be to develop guidelines for reducing the water quality
impact of urban runoff.
5. Major impoundments exert considerable influence in regulating
phosphorus and, to a lesser extent, nitrogen in the lower Susquehanna
River. In addition, these impoundments are highly susceptable to the
proliferation of aquatic plant growths because of their quiescent
nature and reduced silt content. It is therefore suggested that a
detailed study be undertaken in at least one of these impoundments
to address the following key areas: the lateral, longitudinal and
vertical distribution of nutrients on a seasonal basis; exchange
rates at the mud-water interface including characterization of the
bottom sediment; existing algal growth conditions and species
diversity; growth potential through a series of bioassay analyses;
and development of nutrient-algal relationships for inclusion in a
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predictive model. The literature is abundant in material dealing
with lake eutrophi cation and it is quite conceivable that much of
79
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it would be applicable to and assist in the design of such an
impoundment study.
-------
80
Acknowledgements
The authors wish to acknowledge and express their gratitude to
the following governmental and institutional agencies for having
extended the assistance and cooperation that facilitated the collection,
analysis and evaluation of the data presented in this report:
Pennsylvania Department of Environmental
Resources
Susquehanna River Basin Commission
City of Harrisburg
City of York
City of Lancaster
City of Lebanon
Borough of Selinsgrove
City of Sunbury
Township of East Pennsboro
Borough of Mechanicsburg
Borough of Shippensburg
Borough of Carlisle
Township of Lower Allen
Borough of New Cumberland
Borough of Camp Hill
Borough of Middletown
Borough of Palmyra
Hershey Sewage Company
Borough of Hanover
Borough of Elizabeth
Borough of Red Lion
Township of Penn
Borough of Manheim
Borough of Lemoyne
Borough of Lititz
Borough of Ephrata
Borough of Columbia
U. S. Geological Survey, Department of Interior
Philadelphia Power & Light Company
Pennsylvania Power & Light Company
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APPENDIX
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-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
SUSQUEHANNA RIVER NUTRIENT SURVEY
SAMPLING NETWORK
-------
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
Ibs /day /m
8
2
ro
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ro
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2 o
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33
tn
m
m
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a>
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o
CO
m
>
co
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I
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I
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ro
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WEST BRANCH
SHAMOKIN CREEK
PENNS CREEK
JUNIATA RIVER
CONODQGUINET CREEK
HARRISBURG E & W SHORE
YELLOW BREECHES
SWATARA CREEK
CONEWAGO CREEK
CODORUS CREEK
CHICKIES CREEK
TPO4 Ibs/day
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PEQUEA CREEK
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WEST BRANCH
SHAMOKIN CREEK
PENNS CREEK
JUNIATA RIVER
. CONODOGUINET CREEK
V, HARRISBURG E & W SHORE
YELLOW BREECHES
SWATARA CREEK
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CHICKIES CREEK
CONESTOGA CREEK
PEQUEA CREEK
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c
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-------
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TN Ibs/day
TPO4 Ibs/day
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NO3 Ibs/day
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SHAMOKIN CREEK
PENNS CREEK
JUNIATA RIVER
CONODOGUINET CREEK
HARRISBURG E & W SHORE
YELLOW BREECHES
SWATARA CREEK
CONOWAGO CREEK
CODORUS CREEK
CHICKIES CREEK
CONESTOGA CREEK
PEQUEA CREEK
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z c g
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CD
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YELLOW BREECHES
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2 c O
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CONOWAGO CREEK
CODORUS CREEK
CHICKIES CREEK
CONESTOGA CREEK
PEQUEA CREEK
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ro m
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>
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to
O
m
-------
-------
1
I Land area figures (acres and square miles) were determined for
Ithe following sub-divisions within the lower Susquehanna River Basin:
SUB-DIVISION
1
I Major cities of
greater than
125,000 inhibitants
AREA
Harrisburg
Lancaster
Lebanon
York
LAND AREA
mi
7.6
7.2
4.6
5.3
2 acres
4,864
4,608
2,944
3,392
POPULATION
67,880
57,589
28,572
50,335
POPULATION
pop/mi2
8,931
7,998
6,211
9,497
DENSITY
pop/acre
13.45
12.50
9.70
14.84
Major Urbanized
Areas
1
1
1
Counties
1
1
1
Harrisburg
Lancaster
York
Adams
Cumberland
Dauphin
Juniata
Lancaster
Lebanon
Northumberland
Perry
Snyder
York
78
39
37
526
555
518
386
946
363
453
551
327
909
49,920
24,960
23,680
336,640
355,200
331,520
247,040
605,440
232,320
289,920
352,640
209,280
581,760
240,751
117,097
123,106
56,937
158,177
223,834
16,712
319,693
99,665
99,190
28,615
29,269
272,603
3,086
3,002
3,327
108
285
432
43
338
275
219
52
90
300
4.82
4.69
5.20
0.17
0.45
0.68
0.07
0.53
0.43
0.34
0.08
0.14
0.47
^H
1
1
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