An Introduction to Sedimentsheds: Sediment and its
Relationship to Chesapeake Bay Water Clarity

STAC Workshop Report
January 30-31
Annapolis, MD

STAC Publications 07-002


-------
About the Scientific and Technical Advisory Committee

The Scientific and Technical Advisory Committee (STAC) provides scientific and
technical guidance to the Chesapeake Bay Program on measures to restore and protect the
Chesapeake Bay. As an advisory committee, STAC reports periodically to the
Implementation Committee and annually to the Executive Council. Since it's creation in
December 1984, STAC has worked to enhance scientific communication and outreach
throughout the Chesapeake Bay watershed and beyond. STAC provides scientific and
technical advice in various ways, including (1) technical reports and papers, (2)
discussion groups, (3) assistance in organizing merit reviews of CBP programs and
projects, (4) technical conferences and workshops, and (5) service by STAC members on
CBP subcommittees and workgroups. In addition, STAC has the mechanisms in place
that will allow STAC to hold meetings, workshops, and reviews in rapid response to CBP
subcommittee and workgroup requests for scientific and technical input. This will allow
STAC to provide the CBP subcommittees and workgroups with information and support
needed as specific issues arise while working towards meeting the goals outlined in the
Chesapeake 2000 agreement. STAC also acts proactively to bring the most recent
scientific information to the Bay Program and its partners. For additional information
about STAC, please visit the STAC website atwww.chesapeake.org/stac.

Publication Date:

May 2007

Publication Number:

07-002

Cover photo of sediment plumes provided by Jeff Halka, Maryland Department of
Natural Resources.

Mention of trade names or commercial products does not constitute endorsement or
recommendation for use.

STAC Administrative Support Provided by:

Chesapeake Research Consortium, Inc.

645 Contees Wharf Road

Edgewater, MD 21037

Telephone: 410-798-1283; 301-261-4500

Fax: 410-798-0816

http://www.chesapeake.org

2


-------
Table of Contents

1)	Executive Summary	3

Goals	3

Conclusions	3

Recommendations	5

2)	Agenda	7

3)	Presentation Summaries	10

4)	Discussion Notes	12

5)	List of Attendees	23

3


-------
Executive Summary

On January 30-31, 2007 the Chesapeake Bay Program's (CBP) Sediment Workgroup and
the CBP's Science and Technical Advisory Committee convened a workshop titled: "An
Introduction to Sedimentsheds: Sediment and its Relationship to Chesapeake Bay Water
Clarity." Sedimentshed is a new concept, and is defined as the area that contributes the
sediment which directly influences water clarity in near-shore Submerged Aquatic
Vegetation (SAV) grow zones. For further explanation of sedimentshed, please see the
recently released report available at www.chesapeakebav.net/pubs/FinalSedshedsReport.
The twenty-six invited participants to the STAC workshop included technical experts in
sediment, submerged aquatic vegetation (SAV) and water clarity and policy experts in
state programs and total maximum daily load (TMDL) implementation.

Goals:

•	To provide a forum to share important insights from all invited experts on
sediment, its impacts on water clarity and SAV.

•	To review and comment on the Sediment Workgroup's draft report "An
Introduction to Sedimentsheds: Addressing Sediment and Its Relationship to
Chesapeake Bay Water Clarity."

•	To provide the Sediment Workgroup with focused guidance and next steps for
addressing sediment impacts to Bay water clarity.

Conclusions:

1.	Different types of sediment have different ecosystem effects, and should be
regulated accordingly.

a.	Sand is a prerequisite for the establishment of healthy SAV beds. Sources
of sand may need to be maintained rather than reduced.

b.	Silts are beneficial to marshes, though they also play a role in increasing
turbidity.

c.	The smallest clay-sized materials are the most readily suspended and are
the ones of most concern for water clarity. This type of sediment requires
the most regulatory attention. This so-called background, or
continuously suspended sediment is the least studied and least
understood aspect of sediment dynamics in the Bay.

2.	There appears to be a relationship between nutrient loading and the amount of
small material (clays, algae and microscopic remains of organisms) that remain
in suspension during the SAV growing season. This background suspended
sediment appears to settle more slowly in a eutrophic system, exacerbating
water clarity problems. Further reduction of nutrients coming into Bay waters
may assist in reducing the background suspended sediment concentrations and
increase water clarity.

3.	SAV recovery and/or restoration require many factors besides decreased
suspended sediments. Bottom sediment composition (especially sand content),

4


-------
low to moderate dissolved nutrients, minimum bed dimensions, adequate
recruitment, proper water temperature, and species appropriate to the local
environment are among these factors. Some rapid SAV recovery is occurring in
areas with high turbidity, which is not entirely understood.

4.	We need to understand what has changed historically in the Bay to help
determine appropriate management actions to improve water clarity to help
restore SAV. In particular, why was the Bay ecosystem healthier in the past in
spite of apparently equal or greater sediment loads from watershed sources?
Examination of historic information could also be used to ensure the appropriate
mechanistic processes have been included in the new 2007 CBP Water Quality
model.

5.	The 2007 CBP Water Quality model is much more advanced than the 2002
model. It is based on our current understanding of sediment transport and the
relationship to clarity and SAV. It will be a useful tool to provide insight into
sediment sources and transport processes in the Bay and help evaluate
management scenarios to improve water clarity. However, it is still under
development and will require significant verification, sensitivity testing, and
adjustment before its predictions may be considered reliable. Some of the
remaining questions for Sedimentshed delineation coincide with the testing
needs of the model and therefore may be pursued simultaneously. The model
should not be relied on exclusively; other research and management tools can
offer insights that the model cannot. Historical and paleoecology investigations
that correlate chronological onset of stressors and long-term trends of valued
living resources and water quality conditions may offer a means to prioritize
among these stressors.

6.	The Sediment Workgroup (SedWG) created the foundation required to develop
Sedimentsheds and advanced our understanding of sediment sources to the Bay.
Using advanced statistical techniques, it identified similar segments of the Bay
where excessive suspended sediments are causing water clarity impairment.
Delineation of Sedimentsheds is not currently feasible with the available data
sets, but it will be advanced through the use of the forthcoming CBP Sediment
Transport model and possibly by sediment tracer studies using biological and
geochemical sediment "fingerprints."

Recommendations:

Workshop recommendations are organized in five categories: recommendations for
further research, further analysis of existing data, 2007 Water Quality model, Sediment
Workgroup action, and sediment management techniques.

5


-------
1.	Recommendations for further research

a.	What controls the dynamics and abundance of the background suspended
sediment load most responsible for surface water turbidity in shallow water SAV grow
zones?

b.	What are the specific sources of suspended sediment affecting nearshore SAV
habitat in upper, middle and lower areas of the Bay? Consider targeted sediment tracer
studies.

c.	How do different shoreline stabilization techniques affect local SAV habitat
quality?

d.	When and where are other causes of SAV habitat degradation more important
than suspended sediment associated turbidity?

e.	Quantify the sediment trapping ability of the Estuarine Turbidity Maximum
(ETM) for both fine grained and coarse sediment. Consider seasonal characteristics,
especially the SAV growing season.

f.	Determine if tidal tributaries are a source or sink of fine grained sediment to the

Bay.

2.	Recommendations for further analysis of existing data

a.	Are there quantifiable trends in Bay surface water turbidity? Is there a seasonal
cycle in background turbidity, and how does background turbidity vary spatially? Are
long term trends quantifiable? If so, are the trends different in nearshore and offshore
waters? Are there clear correlations between turbidity trends and SAV coverage? Both
CBP monitoring data and historical data prior to initiation of regular CBP monitoring
should be explored.

b.	What is the relationship, if any, between nearshore turbidity and center-channel
turbidity? Does lateral transport of suspended sediments allow for close connections, or
are the two environments essentially independent, and under what conditions? Both the
CBP monitoring program databases and separately funded studies can be brought to bear
on this issue.

c.	Analyze recently acquired nearshore water clarity data for model verification.

3.	Recommendations for the new 2007 CBP Water Quality model related to
nearshore clarity and Sedimentshed delineation

A variety of exploratory analyses using the new Water Quality model with its improved
sediment transport representation will help to clarify questions of fundamental
importance for nearshore water clarity and the delineation of Sedimentsheds. Among
these are:

a.	Adjusting the settling speed of the slowest settling particle class to investigate
potential turbidity improvements due to nutrient reductions.

b.	Reducing different sediment sources separately to investigate changes in
nearshore turbidity. This should include changing the relative proportions of the different
sediment classes in the input loads to test model sensitivity to this relatively unknown
factor. As a corollary, ask whether planned reductions in watershed sediment sources

6


-------
due to phosphorus controls will achieve water clarity goals, or whether additional actions
will be required, or whether any watershed reductions will have a measurable affect on
nearshore water clarity downstream of the ETM.

c.	Decreasing the erodibility of fine sediments to represent biostabilisation by
oyster beds, SAV beds, benthic biofilms, etc. Also increasing erodibility in some areas to
represent the effects of increased bioturbation as benthic habitat quality improves.

d.	Further develop nearshore model cells to include increased wave forcing in
shallow water, sediment trapping in marshes, and improved time variability of shoreline
erosion.

4.	Recommendations for Sediment Workgroup Action

a.	Coordinate more with the Modeling Subcommittee in the near future.
Specifically, the SedWG can assist modeling staff with suspended sediment scenario
development and help verify sediment transport model predictions.

b.	Coordinate with on-going SAV recovery and restoration activities by
identifying nearshore sand sources in the Bay, and nearshore sediment distributions
conducive for SAV recovery and restoration.

c.	Coordinate with US ACE Shoreline Erosion Study regarding regional
determination of appropriate, environmentally-sensitive shoreline-stabilization measures
to use when shoreline hardening is to occur.

d.	Coordinate analysis of data on historic sediment load trends.

e.	Continue to identify research needs to help fill in knowledge gaps.

5.	Proposed sediment management techniques

•	Consider separate management techniques for fine and coarse sediments.

•	Develop better targeting of SAV plantings that take into consideration bottom
sediment characteristics for SAV restoration.

•	Examine site specific, environmentally-sensitive shoreline management activities
for SAV habitat improvement.

•	Evaluate the efficacy of sediment management through wetland
cr eati on/r e stor ati on.

•	Consider the beneficial placement of dredged material (particularly sandy dredged
material)

7


-------
Agenda

An Introduction to Sedimentsheds: Sediment and Its Relationship
to Chesapeake Bay Water Clarity
January 30-31, 2007
Doubletree Hotel, 210 Holiday Court, Annapolis
Calvert "C" Room

Objectives:

1.	To provide a forum to share important insights from all invited experts on
sediment and its consequent impacts on water clarity and submerged aquatic
vegetation.

2.	To review and comment on the Sediment Workgroup's efforts to date on sediment
and its relationship to Chesapeake Bay water clarity.

3.	To provide the Sediment Workgroup with focused guidance in determining
appropriate next steps for addressing sediment impacts to Bay water clarity as
necessitated by the 2010 reevaluation.

Tuesday, January 30th

8:15 Registration, coffee, continental breakfast available

9:00 Welcome, Introductions, Needs and Outcome of Workshop: Jeff Halka, MGS
and Keely Clifford, EPA

9:15 Overview of Major Sediment Sources - Jeff Halka

Draft Sediment Budget, "Good"vs. "Bad" Sediment

9:45 Water Quality/Clarity Criteria and Needs for 2010 Re-evaluation - Rich Batiuk,
EPA

How new state water clarity criteria/water quality regulations were developed and why.

What the water clarity regulations are and how do we measure attainment?

What needs to happen with sediment during the next 3 years leading up to the 2010 Re-
evaluation?

10:15 Break

10:30 Factors Affecting Light Attenuation and Shallow Water Clarity Impairment -
Chuck Gallegos, Smithsonian Environmental Research Center

Discussion of Suspended sediment, light penetration and other light attenuation components

11:00 SAV Habitat Requirements Other Than Light - Evamaria Koch, UMCES

Geological and geochemical processes that affect SAV growth and survival

8


-------
11:30 Fine-Grained Sediment Transport Processes in Chesapeake Bay - Larry Sanford,
UMCES, and Carl Friedrichs, VIMS

Physical, geological, and biological processes that control suspended sediment concentrations
and transport patterns from sources to sinks in the estuary and its tidal tributaries

12:00 New Water Quality/Sediment Transport Model and Expected Outputs - Carl
Cerco, U.S. Army Corps of Engineers, ERDC

Expected improvements in suspended sediment predictions and identification of remaining
shortcomings; overview of how the model addresses components of light attenuation including
filter feeders; expected model outputs; expected uses

12:30 Lunch (provi ded)

1:30 What Sediment Workgroup Has Done So Far, plus discussion - Lee Curry, MDE
2:30 Overview of Break Out Sessions and Discussion of Topics - Keely Clifford

We will break into two groups for each of the three workshop breakout sessions; with assigned
facilitators and recorders for each group. Groups will brainstorm for 1 hour on assigned
questions then report major findings back to the entire group for plenary discussion. Suggested
topics are listed in Appendix 1; final topics and the order in which they will be addressed will be
decided during this discussion. Breakout rooms are the primary meeting room (Calvert C) and
the Talbot Room.

3:00 Break

3:15 Break Out Session 1

4:15 Breakout Group Reports and Plenary Discussion
5:00 Adjourn

6:00 Group dinner at Rams Head Tavern, 33 West Street, Annapolis (we reserved
the Tea Room)

Wednesday, January 31st, 2007

8:15	Continental breakfast

9:00	Summary of Day 1: JeffHalka

9:15	Break Out Session 2

10:15	Break

10:30	Break Out Session 3

11:30	Breakout Group Reports and Plenary Discussion for both morning sessions

9


-------
12:30 Lunch (provi ded)

1:30 Final Plenary Session

•	summary discussion of breakout results and workshop conclusions

•	recommendations for Sediment Workgroup to help determine next steps and
appropriate actions for addressing sediment impacts to Bay water clarity

2:30 Discussion of Workshop Report writing responsibilities. Participants without
writing responsibilities may leave.

3:00 Adjourn

Appendix 1 - Suggested Breakout Session Topics

Three questions are identified here with the idea that both breakout groups will address
the same question during each breakout session. The different perspectives will be
compared and unified during the subsequent plenary discussions. However, additional or
alternative topics may be identified and agreed upon by the workshop participants during
the 2:30 discussion on January 30, such that the total number of questions may range
between 3 and 6 and the order of the questions may change.

Question 1:

What aspects of suspended sediment variability are most important for water clarity?
Question 2:

Does sediment have the same impact on water clarity and SAV in all areas of the Bay?
Which areas of the Bay would most likely benefit from local sediment reductions?

Question 3: What is the appropriate scale and once decided, what is the optimum
approach to delineating sedimentsheds?

10


-------
Presentation Summaries

Please see full presentations at:

http://www.chesapeakebav.net/calendar.cfm?EventDetails=8176&DefaultView=2:

Needs and Outcome of Workshop - Keely Clifford, EPA/CBPO

•	Forum to share expert information on sediment, water clarity and SAV

•	Review and comment on SedWG work

•	Provide SedWG guidance for next steps

Overview of Major Sediment Sources - Jeff Halka, SedWG co-chair, MGS

•	Sediment comes from the watershed, tidal areas, ocean and internal processes;
Resuspension can contribute huge quantities to suspended particle loads

•	"Good" and "bad" sediment

•	Transport of "bad" fine-grained sediment is poorly understood

Primer for Chesapeake Bay Water Clarity Criteria, Shallow-Water Designated Use
and State's Water Quality Standards - Rich Batiuk, EPA/CBPO

•	MD, VA, DE, and DC have adopted the 185,000 acre shallow-water Bay grasses
restoration goal into their state water quality standard regulations.

•	These state water quality standards regulations have water clarity criteria, SAV
restoration acreages and detailed criteria attainment assessment procedures.

•	We are heading into a Baywide Total Maximum Daily Load (TMDL) by 2010.

SAV Habitat Requirements Other Than Light - Evamaria Koch, UMCES

•	SAV stabilize the sediments they colonize.

•	Sediment composition is a key parameter for SAV.

•	Breakwaters do not appear to benefit SAV in the long-term, only in the short-
term.

•	Loss of land can induce loss of SAV via:

o Increased wave exposure
o Increased current velocities
o Increased water depth and bottom scour
o A change in sediment composition

•	Loss of land and induce gain of SAV via:

o Ample supply of sand

o Creation of new shallow water habitat within photic zone
o Provision of sediment to maintain existing shallow water
habitat within photic zone

Factors Affecting Light Attenuation and Shallow Water Clarity Impairment -

Chuck Gallegos, SERC

•	Presented evidence that eutrophication leads to higher concentrations of inorganic
suspended solids.

11


-------
•	He thinks organic loading to the sediment may make it a fluff, which does not
readily settle.

•	Turbidity problem cannot be solved by limiting TSS loading alone.

•	To solve the turbidity problem we need to solve the nutrient
loading problem.

Fine Grained Sediment Transport Processes in Chesapeake Bay - Larry Sanford,

UMCES & Carl Friedrichs, VIMS

•	There are at least two separate suspended sediment populations:

o Inorganic, rapidly settling sediment concentrated near bottom.

Sediment transport researchers have generally focused their work on
these sediments, however, these sediments are probably not causing
water clarity/light attenuation problems in the upper water column,
o "Background sediments," which are less aggregated, more organic and
slowly settling particles. There has been relatively less research on
these likely detrimental sediments which cause water clarity problems.

New Water Quality/Sediment Transport Model and Expected Outputs - Carl Cerco,

USACE, ERDC

•	The 2007 Water Quality model is much more advanced than the 2002 model

•	New model incorporates: mechanistic sediment transport including resuspension
by waves and currents, 3 solids classes (clay, silt and sand), advanced optical
model, revised expert estimates of bank sediment loads, and solids filtration by
living resources.

•	It will give outputs relating to load reductions.

What the SedWG has done so far - Lee Currey, MDE, Sediment Workgroup Co-Chair

•	The Sediment Workgroup created the foundation required to develop a
sedimentshed (area, including upland, nearshore and sub-aqueous, that contributes
the suspended sediment loads that directly influence water clarity in SAV grow
zones).

•	Using Bay monitoring data and cluster analysis with light attenuation, salinity,
and fixed suspended solids (FSS) as the input parameters, the Sediment
Workgroup clustered segments of the Bay where excessive FSS was causing
water clarity impairment.

12


-------
Discussion Notes:

** Notes on presentations capture discussion following the presentations, not the presentations
themselves. **

DAY ONE (January 30, 2007)

Workshop Goals and Objectives	Keely Clifford

1. No significant comments/discussion

Overview of Major Sediment Sources	Jeff Halka

Jeff Halka, MD Geological Survey, gave a presentation on the draft Chesapeake Bay
sediment budget.

Comments/Discussion Following Presentation:

•	Q: Is it appropriate to consider a holistic sediment budget if the concern is excess
suspended sediments that impair water clarity to the detriment of SAV?

o A: What is most needed is a suspended sediment budget.

•	Q: Does the Chesapeake Bay Sediment Budget table (Table 3-1 in the
sedimentsheds report) take into consideration major episodic or unusual events,
such as Agnes?

o A: If events are captured in the monitoring data, they will be included.
Agnes is not included in the budget, but more recent events, such as the
January 1996 flood and a few March flooding events that occurred in
recent years show up in the RIM data for the Susquehanna.

•	Q: What about sediments behind dams?

o A: This is something we are aware of, but we are not yet sure how to deal
with. It could be that more sediment is added to the system as dams fill up
and lose capacity to trap sediment.

•	Q: Is it going to be impossible to achieve our sediment goal when taking into
account unusual events and dams?

o A: 40+ dams across the watershed are built into the Phase 5 model.

•	It was pointed out that we cannot assume that hardening stops near-shore erosion.
Jeff said he did not assume this when developing the budget.

•	What point are you trying to make with this table? Where do we stand? Can you
even do an error analysis on the estimates? What studies need to be done to get
estimates?

•	Q: Do we actually need a well-constrained budget?

o A: We do need to have a sediment budget as we move into TMDLs.

•	Recommendations to improve the sediment budget table:

o Need to take a cut at error estimates as was recommended in the STAC

review of the Phase 5 model,
o Should try to fill in the table over this year with our best estimates,
o Need a sense of uncertainty and certainty,
o Would look like a gap analysis, which would be helpful,
o When you have a new number, you need to defend why it changed.

13


-------
•	Q: Should resuspension be included in the sediment budget?

o A: Perhaps resuspension should not be included in the budget because
resuspension is not really an external source. Since it is not new material,
it has already been accounted for.

o However, resuspension does have a huge impact on water clarity and
SAV.

o A line could be added to the budget for deposition to cancel out
resuspension.

o A sediment budget needs both sinks and sources, and the current table
only shows the sources. Maybe this is a table of sediment sources, and not
a sediment budget.

•	The budget's time scale should be clarified. (Are we talking about the growing
season? Winter? Etc.)

Water Quality/Clarity Criteria and Needs for 2010 Re-evaluation Rich Batiuk

Rich Batiuk, EPA, gave a presentation on the water quality/clarity criteria and needs for

the 2010 re-evaluation.

Comments/Discussion Following Presentation:

•	What about the no-grow zone? How is this accounted for? Should it be included
or not? This should be addressed as the states move to update their regulations.

•	Q: How do you create a pass/fail grid for turbidity?

o Take measurements in the shallows at calibration stations, set up tables to
compare turbidity measurements, and compare and calibrate to the Kd
measurement.

o Look at tributary levels.

o As more data comes in, calibration will be updated.

•	The SAV Workgroup is considering updating/revising the SAV goal. There are
very shallow areas and/or areas that have not had large growth previously that are
now being rewarded. How would data be included in the standards if improved
data for the new goal becomes available?

•	Q: Is it a problem that we are extrapolating the data from deeper areas into the
shallows? Is this an accurate picture?

o A: Yes, we acknowledge it, but we are not sure what else to do at this
point (Rich Batiuk).

o Suggestion: Could you make adjustments to the light requirements to
account for areas where you are not monitoring to make up for the use of
extrapolations from the deep water?

Factors Affecting Light Attenuation and Shallow Water	Chuck Gallegos

Clarity Impairment

Chuck Gallegos, Smithsonian Environmental Research Center, gave a presentation on

suspended sediment, light penetration, and other light attenuation components.

Comments/Discussion Following Presentation:

•	Historically, SAV and oysters were high, sediments were high, and nutrients were
low.

14


-------
•	We need a better understanding and consideration of historical information.

•	We have areas where nutrients have decreased, but there were little changes in
light, and positive changes in SAV (such as the Patuxent River).

SAV Habitat Requirements Other Than Light	Evamaria Koch

Evamaria Koch, University of Maryland Center for Environmental Science, gave a
presentation on the geological and geochemical processes that affect SAV growth and
survival.

Comments/Discussion Following Presentation:

It was suggested that degradable fabric bags filled with sand be used as breakwaters in
front of SAV beds. These tubes would degrade over the years, releasing sand. However,
when they degrade, wave action over the SAV beds would increase. Would this destroy
the SAV? If the area has waves above the threshold for survival, yes. Also, once the
bags degrade, the supply of sand will eventually end.

•	Q: Is data available to determine sand sources and how far away they are from
SAV beds?

o A: That is currently being worked on.

•	It was suggested that we determine where the Bay's sand sources are and then try
to "protect" (i.e. allow them to erode making the sand available to the ecosystem)
those areas since, according to Evamaria's presentation, sand is needed for SAV
establishment/growth.

•	Issues and considerations in the upper Bay and freshwater systems are different
than what is presented here.

Fine-Grained Sediment Transport Processes Larry Sanford & Carl Friedrichs
in Chesapeake Bay

Larry Sanford, University of Maryland Center for Environmental Science, and Carl
Friedrichs, Virginia Institute of Marine Science, gave a presentation on the physical,
geological, and biological processes that control suspended sediment concentrations and
transport patterns from sources to sinks in the estuary and its tidal tributaries.
Comments/Discussion Following Presentation:

•	Need to look at the relationship between shoreline erosion and SAV growing
seasons.

•	Q: How does low-density floe fit into the model and to what do they correspond?

o A: In the model, they are being treated as clay. The model does not know

particle size and density, just settlement rates,
o What are the management implications? Different sediment categories
have different strategies.

•	Does the formation of sediment "blobs" (agglomerates) decrease clarity? Is there
a seasonal component? Would clarity increase by pulling sediment all together to
form "blobs"?

•	How does turbidity change in relation to concentrations of particles at various
sizes?

•	We should look into how different size and settling rate particles affect turbidity.

•	Q: How effective is the ETM as a sediment trap?

o A: Maybe more effective than we previously thought.

15


-------
•	How do the patterns occurring in the main-stem Bay affect the near-shore
SAV/water clarity?

•	What is the implication of the exchange, if any, between the background sediment
population and the resuspended sediment population for water clarity?

New Water Quality/Sediment Transport Model and Expected	Carl Cerco

Outputs

Carl Cerco, U.S. Army Corps of Engineers Engineer Research and Development Center,

gave a presentation on the new water quality/sediment transport model.

Comments/Discussion Following Presentation:

•	Q: Is the potential connection between nutrients and suspended solids dynamics
included in the model, or is there room to include it in the future?

o A: It is not there yet, but it might be able to be included in the future. The
relationship needs to be documented first to ensure that it is happening. It
needs to be studied and understood and then put into mathematics for
incorporation into the model.

•	Q: How do you account for SAV when the minimum model depth is 5 feet?

o A: An SAV sub-grid, which is divided into increments of 0.25 meters, is
incorporated into model littoral cells and can be used to look at things like
light.

•	Q: Can you resolve the resuspension issues in the shallows?

o A: The modeling team does not have information on light attenuation in
the shallows. Data needs to be provided to the modeling team in order to
validate it in the model.

•	Q: Can the model separate impact of clarity in shallow sources (upland, bank
loads, resuspension, etc.)?

o A: Yes, to the best that can be done right now.

•	Q: What are the management questions that the model can handle?

o A: It is oriented towards being able to respond to questions about load
reductions.

•	Q: Can the model run historic scenarios from times when watershed and shoreline
sediment loading were perhaps greater, but oysters were healthy, nutrient loading
lower, and SAV greater?

o A: The scenarios can be run but there is no guarantee the results will
agree with our conception of the past. Substantial effort is required to
assemble historic data sets and to develop appropriate model parameters.

What the Sediment Workgroup Has Done So Far	Lee Curry

Lee Currey, MD Department of the Environment, gave a presentation on what the

Sediment Workgroup has done so far regarding the sedimentsheds concept.

Comments/Discussion Following Presentation:

•	Are there simple rules to determine where sediment is coming from and can you
use the model to test these rules?

•	Q: Do we need to look at both natural sources and anthropogenic sources of
sediment?

16


-------
o A: Yes, we need to recognize both of these components, but also

recognize that in cases where natural sources are being delivered at natural
rates it is not clearly appropriate (and may not be practicable) to intervene
to alter this. For example, shoreline erosion generates suspended solids,
but it is a fundamental natural process of the Bay ecosystem.

Need to recognize what the problems are and reduce uncertainty before
developing management actions.

Q: Can the model forecast feedback from nutrient reductions? Can it help look at
the relationship between sediments and nutrients?

o A: Looking at the relationship between sediments and nutrients may not
make it into the model update for Phase 5, which is to be completed in
April.

Are the western tributaries beyond management for suspended solids?

Some participants were concerned about what would happen if we over-controlled
for sediment problems, which would result in the loss good sediment. Good
sediment is important for certain watershed components like wetlands. Rich
Batiuk said that he was not concerned about this at this time given current
sediment rates.

We are trying to achieve a reduction in suspended solids (sediment) in the water
column.

Ways that we know to reduce sediment include no-till, buffers, etc. However,
these are watershed fixes. Are there tidal water fixes?

The relationship between load reductions and suspended sediment is not linear.
What reductions would you see over what timeframe and where? Can we make
certain reductions in certain areas and not see improvement in clarity or SAV?
We need to look at this as it will be important for management decisions/actions.
It is thought that sediment loading to the Bay from watershed sources was greater
during the late 19th and 20th centuries than at present. Yet, the Bay was
healthier. Additionally, shoreline erosion has been essentially stopped in many
urban waterways via stabilization measures; thus natural loading from shoreline
erosion is also reduced. Maybe we should explore this more.

SAV recovery is going to be very local. Since water quality monitoring data is
taken from the middle of the Bay, does it relate to the near-shore turbidity levels?
The battle will be won with SAV, not clarity, and there may or may not be a firm
relationship.

We should determine what sediment sources should be "protected" - free from
certain management practices. We also should look for areas that need protection
to keep sediments in place.

There is a possibility that we may not be able to do anything to reduce suspended
sediment levels in the mesohaline Bay if sediment is derived from resuspension
and near shore erosion. Greater historic SAV health in this area may be related to
former historic presence of massive oyster beds in middle Bay.

Julie Herman noted that there is a model for Northumberland County, VA that is
used to determine suitable living shorelines.

17


-------
• Q: Did historical large oyster reefs affect wave attenuation, thereby affecting
SAV? Do we need to consider this in the timeframe of the historical SAV data
used to determine the SAV goals?

o A: Maybe in Virginia where intertidal reefs historically occurred, but not
in Maryland. Maryland's historic oyster reefs were deeper and probably
largely below active wave depth.

DAY TWO (January 31, 2007)

Discussion	All

Greg Allen, EPA, and Kelly Shenk, EPA, facilitated a discussion on the second day of
the workshop. Questions to be addressed in the discussion included:

•	What questions can we ask the model?

•	What management questions can it not answer?

•	What is the added value of delineating sedimentsheds?

•	What information do we need to address tidal erosion?

QUESTION: What are the management questions that we feel are important to have
answers for? (Responses below are in no particular order.)

1)	It is anticipated that a substantial portion of the remaining Bay shoreline that is
not yet stabilized will ultimately be stabilized, since property owners have the
legal right to do this. What will the model show in terms of sediment reductions?
Would there be benefits to SAV by implementing living shoreline techniques
versus other less environmentally-sensitive techniques?

2)	If we implement living shorelines on X% of the possible shoreline, what will the
model show in terms of sediment reductions?

3)	What are the key factors affecting where SAV beds were historically? Is there a
way to target these factors based on historical information?

o The model could be used to guess at trends (shell reefs, deposition rates,
etc.).

4)	If we reduce watershed inputs, does it have a significant effect on near-shore
water clarity?

5)	Will controlling phosphorus in the watershed sufficiently address water clarity in
the Bay? Or are additional actions needed to control sediment?

6)	Where is deposition most likely to occur?

o The model can be used for this, although they haven't used it to answer
this question yet.

o Does the model agree with historic patterns of deposition? The model's
deposition predictions should be compared to literature deposition rates.

7)	Where does oceanic input go?

o Into the Bay and up the tributaries?

o A grain size profile would be useful.

8)	Why was the Chesapeake Bay clearer in the historic past and less clear now?
What role does sediment play in this? How many changes (oyster beds, SAV
beds, sediment loading rates from watershed and shoreline sources, sediment

18


-------
velocity, reduction in nutrient loading, etc.) have to occur and to what degree in
order to get the water as clear as it was 100 years ago?

o A better understanding of the historic trends is needed to better
predict/understand future conditions/predictions. We need a better
understanding of historical trends around resources of concern,
o Explore deposition rates, settling velocities, shell on bottom, and SAV.
o Conduct sensitivity analyses: (1) shut off watershed sediment inputs, (2)
shut off shoreline erosion inputs, and (3) increase net deposition/decrease
settling speeds,
o The model cannot address SAV burial.

9)	Extreme weather events, such as Agnes, should be simulated. Model input decks
would need to be generated in order to do this. Look at the affects Agnes had on
SAV.

10)	Is the ETM a significant sediment trap, or is it just a "toll plaza"?

11)	What dominates sediment loads in the upper, middle, and lower Bay and above
and below the ETM (tidal energies, legacy sediments, etc.)? How does this affect
management?

12)	Are tidal tributaries sources or sinks (particularly below the ETM)?

o Julie Herman looked at this on the York River,
o Use velocity from the hydrodynamic model with TSS data.

13)	Where are the sediments coming from (mouth of the Bay, head of the Bay, etc.)
that negatively affect near-shore water clarity?

o Answering this question will help prioritize the other questions listed in

this discussion and it will help direct management,
o Are legacy sediments significantly affecting water clarity? What is the

quality of the legacy sediment?
o Which watershed sources are having a more significant negative impact on

water clarity: upland sources or channel corridor sources?
o Are the watershed sources important? Stream bank sources? Ocean
sources?

o Are the internal processes dominant?

o Is there a relationship between the river input data for TSS and the down-

tide water clarity?
o Where is suspended sediment in SAV beds coming from?
o Suggestion: Fingerprint the suspended sediment affecting SAV in near-
shore areas.

14)	If a particular source of sediment is reduced by X%, what % improvement would
we see in water clarity and SAV?

o Lag time and timescales should be considered for management measures,
o What would the lag time be?

o Monitoring is needed to determine if (and by how much) a particular Best
Management Practice (BMP) actually reduces sediment and results in a
water clarity improvement,
o Monitoring data should be analyzed so that we better understand the
connection between water column concentrations and clarity.

19


-------
o Suggestion: Use a tracer at a source location to help understand sources,
patterns, transit time, lag time, etc.

¦	Tracers are only good on a small scale and they need to be
repeatedly released and tracked.

¦	Allen Gellis told the group that there was an RFP submitted to the
Chesapeake Bay Program on sediment transit time, but the project
did not get funded. This project could have also quantified
whether sediment got through the ETM.

15)	Is water clarity different in the shallows compared to in the channel? Since water
quality monitoring data is taken from the middle of the Bay, does it relate to near-
shore turbidity levels?

o Suggestion: This needs to be in the model.

o Instead of looking at segment averages for clarity, could we focus on near-
shore clarity only, since that is the only area important for SAV?

16)	What is the background turbidity? Why is background turbidity higher in the
summer than in the winter?

17)	How do we manage for different species of SAV with different water clarity
requirements?

o Suggestion: Track changes in species of SAV overtime.

18)	Should we try to preferentially manage fine versus coarse sediment or encourage
continued delivery/availability of coarse sediment?

19)	Should we be managing for mid-Bay?

20)	What parameters need to be changed for the water to be clear?

o Decrease erodibility
o Increase fall velocity

o How much do these need to change to clear the water column?
o Classify by sediment grain size.

21)	Look at impacts of wetlands on sediment grain size and transport.

o Is there a mechanism in the model to remove fines as a result of wetland

removal, since wetlands trap fines?
o Does an increase in wetland acreage lead to increased water clarity?
(possibly test with the model)

22)	The hypothesis that nutrient reduction may result in more improvements in water
clarity than originally expected due to its connection with sediment settling is an
idea that merits further study.

QUESTION: What is important to SAV and water clarity?

What is important to water clarity and SAV?

Watershed	Shore	Oceanic	Internal

Stream Upland
Corridor

Near shore

Net Settling Biogenic
Deposition Speed

20


-------
•	Are current efforts to reduce phosphorus in the Watershed already reducing
sediment enough or is more needed?

•	What spatial scale should be used?

o Shoreline cells
o Above ETMs
o Below ETMs
o Upper, middle, and lower Bay
o Tributary

•	Model output should be analyzed at different scales to determine what scale is
meaningful and to look for relationships between sources and water clarity/SAV.
How are each of these stressing water clarity and SAV?

•	Spatial and temporal considerations.

•	Fine vs. coarse grains- anthropogenic changes.

QUESTION: What questions can we ask the model?

•	What model parameters can be changed to improve water clarity? To what
degree must the parameters change?

•	What is needed in the model to have increased water clarity with increased
sediment loads? (As was the case in the late 1800's to early 1900s)

QUESTION: Would it be helpful to examine historic trends and compare them to
current conditions? Is a historic model run critical and/or feasible?

•	Gaining a better understanding of why the water was historically clearer despite
the presence of increased sediment loads from watershed and shoreline sources
would help us better understand processes related to clarity.

•	Is it proven that there were higher sediment loads and increased water clarity
historically? May want to look for data to back up this statement.

o There is at least one paper from the 1950s that discusses water clarity in

the Chesapeake Bay.
o Some reservoir sedimentation surveys go pretty far back.

•	A historic model run may not be absolutely necessary. It would require a
significant amount of time and money.

•	It was suggested that historic data sets be analyzed independent of the model
using causal inference techniques. Look more closely at the relationship between
sediment loads and water clarity as far back as possible. Where should we look
for historic sediment load data?

•	It was also suggested that we use the model to do a more general model run in
order to see what it takes to have increased water clarity with increased sediment
loads. No 1950s input deck will be created at this time.

•	Can we look at cores for grain size distribution?

o Cores in headwater tributaries show substantial increases in sediment rates
following European settlement, and likely changes in grain-size. Cores in
the open bay shallow margins do not show increases in rates or grain-size
because physical processes (largely wave energy) have remained largely

21


-------
consistent, preventing excess deposition and maintaining consistent
bottom grain-size.

•	Throughout this process, keep in mind natural vs. anthropogenic sediment
processes.

•	Has grain-size changed? Today do we have more fines (bad sediments) than
sands (good sediments)?

o Is urban development transporting more fines to the system?
o It is important to manage fines over sands at this point.

QUESTION: What are suggested follow-ups for the Sediment Workgroup?

•	Determine what we need from the model now

o Historical

o Affected areas- What areas of the Bay are SAV and water clarity are
impacted and by what sources?

•	What do we need to put into the model?

o What data analyses need to be done
o Develop scenarios for model runs

•	What do we need to verify the model? Research studies to fill in gaps?

QUESTION: What can we do between now and when the model is available?

•	Assemble data sets needed to tweak the model to simulate historical conditions

o Focused on getting a historical output
o Look at relationship between loads and clarity

•	Critical to look at data independently of the model

o Data available from USGS, Marsha Olson, CBI/CBL

QUESTION: What are some management techniques that could be used to decrease
sediment loads in the tidal zone?

•	SAV plantings

o Have been largely unsuccessful except for in sandy areas,
o Is domain of Living Resources Subcommittee, but may be an inadequate
consideration of bottom sediment character and future bottom sediment
character as function of proximity to shoreline stabilization structures,
o More targeted and calculated restoration (spread sand first, sand-based

breakwaters, temporary breakwaters, etc.)
o Better targeting of where to plant

•	Continued efforts to increase populations of oysters/filter feeders.

o Target oyster restoration in geographic areas that would help SAV
restoration.

o Current research suggests that unless you have a huge amount of filter

feeders, clarity doesn't really change,
o Could oyster beds serve as a breakwater for SAV beds?

¦ Offshore oyster beds have shown essentially no impact on near-
shore water clarity and SAV beds.

•	Continue to tackle eutrophication issues and nutrient reductions.

22


-------
•	Target shoreline protection efforts where significant improvements in SAV beds
are most likely to be seen; however this would compromise natural shoreline
character fundamental to the Bay ecosystem, and might induce future SAV losses
via interruption of processes that create and maintain shallow water habitats.

•	Wetland creation/restoration.

•	Beneficial placement of dredged material (particularly sandy dredged material).

QUESTION: What is the added value of delineating sedimentsheds? What does this
concept provide that we do not already have?

•	It may be particularly important to delineate sedimentsheds in areas where SAV is
not doing well, such as in the Mid Bay. Surprisingly, SAV is doing well (meeting
recovery goals) in many areas above the ETMs that receive the greatest delivery
of watershed sediments.

•	If ETM crosses sedimentsheds - divide sedimentsheds above and below ETM.
Controlling sediment above and below the ETM may require very different
approaches.

•	Currently, the Sediment Workgroup is just laying the groundwork for
sedimentsheds. There is not yet enough information to delineate sedimentsheds.

•	This question will naturally be addressed through the process that we discussed
earlier (see above flow chart). It does not need to be decided now.

•	Establishing sediment sources should be added to priority research list.

QUESTION: What information do we need to address tidal erosion?

•	Shoreline erosion is a fundamental natural process. Is there a need from an SAV
management perspective to promote measures that stabilize shorelines if it
compromises overall ecosystem health and may cause long-term problems for the
SAV resource (via interfering with processes that create and maintain shallow
water habitats)

•	Natural shoreline extent is utilized as an indicator of ecosystem health in
Maryland's coastal bay tributaries. Should a comparable indicator be applied to
the Bay's tributaries?

•	Look at good vs. bad sediment, natural processes, man-made effects

•	Consequences of hardened shorelines and how to reverse

•	The feasibility of applying tracer techniques to determine sources of suspended
material in shallow water.

o Geochemical tracers to track background vs. suspended vs. on ground
sediments, as well as upper vs. lower Bay sediments.

•	Leave "natural" erosion processes alone that produce "good" sediment.

•	How do offshore breakwaters work to promote SAV growth and what are the best
designs?

o Maryland Regulatory "order of preference" favors non-structural

alternatives, environmentally sensitive erosion control techniques, living
shorelines where/when feasible during permitting process.

o Better guidance needed for regulators in making permit decisions

23


-------
The workshop proceedings and a summary of workshop highlights will be sent to all
participants for comments to ensure that everyone can and will support the
recommendations that come out of these discussions.

24


-------
List of Attendees

DAY ONE

Greg Allen
Rich Batiuk
Peter Bergstrom
Sally Bradley
Carl Cerco
Keely Clifford
Lee Currey
Rich Eskin
Melissa Fagan
Nina Fisher
Carl Friedrichs
Jack Frye
Chuck Gallegos
Allen Gellis
Jeff Halka
Julie Herman
Michael Kemp
Evamaria Koch
Doug Levin
Shah Nawaz
Mike Naylor
Cindy Palinkas
Sara Pan-
Nancy Rybicki
Larry Sanford
Kelly Shenk
Chris Spaur
Becky Thur
Liz Van Dolah
Jennifer Volk
Ping Wang

U.S. Environmental Protection Agency- Chesapeake Bay Program
U.S. Environmental Protection Agency- Chesapeake Bay Program
National Oceanic and Atmospheric Administration
Chesapeake Research Consortium
U.S. Army Corps of Engineers

U.S. Environmental Protection Agency- Chesapeake Bay Program

Maryland Department of the Environment

Maryland Department of the Environment

Chesapeake Research Consortium

Freelance Technical Writer

Virginia Institute of Marine Science

Virginia Department of Conservation and Recreation

Smithsonian Environmental Research Center

U.S. Geological Survey

Maryland Geological Survey

Virginia Institute of Marine Science

University of Maryland Center for Environmental Science

University of Maryland Center for Environmental Science

National Oceanic and Atmospheric Administration

DC Department of Health

Maryland Department of Natural Resources

University of Maryland Center for Environmental Science

Chesapeake Research Consortium

U.S. Geological Survey

University of Maryland Center for Environmental Science

U.S. Environmental Protection Agency- Chesapeake Bay Program

U.S. Army Corps of Engineers

Chesapeake Research Consortium

Chesapeake Research Consortium

DE Department of Natural Resources and Environmental Control
University of Maryland Center for Environmental Science

25


-------
DAY TWO

Greg Allen
Rich Batiuk
Peter Bergstrom
Sally Bradley
Carl Cerco
Keely Clifford
Lee Currey
Rich Eskin
Melissa Fagan
Nina Fisher
Carl Friedrichs
Jack Frye
Chuck Gallegos
Jeff Halka
Julie Herman
Doug Levin
Shah Nawaz
Cindy Palinkas
Sara Pan-
Larry Sanford
Kelly Shenk
Chris Spaur
Liz Van Dolah
Jennifer Volk
Ping Wang

U.S. Environmental Protection Agency- Chesapeake Bay Program
U.S. Environmental Protection Agency- Chesapeake Bay Program
National Oceanic and Atmospheric Administration
Chesapeake Research Consortium
U.S. Army Corps of Engineers

U.S. Environmental Protection Agency- Chesapeake Bay Program

Maryland Department of the Environment

Maryland Department of the Environment

Chesapeake Research Consortium

Freelance Technical Writer

Virginia Institute of Marine Science

Virginia Department of Conservation and Recreation

Smithsonian Environmental Research Center

Maryland Geological Survey

Virginia Institute of Marine Science

National Oceanic and Atmospheric Administration

DC Department of Health

University of Maryland Center for Environmental Science
Chesapeake Research Consortium

University of Maryland Center for Environmental Science
U.S. Environmental Protection Agency- Chesapeake Bay Program
U.S. Army Corps of Engineers
Chesapeake Research Consortium

DE Department of Natural Resources and Environmental Control
University of Maryland Center for Environmental Science

26


-------