Summary Minutes of the
U.S. Environmental Protection Agency (EPA)

Science Advisory Board (SAB)

Hypoxia Advisory Panel (HAP) - Subgroup Conference Call on
Characterization of Nutrient Sources, Fate, and Transport
November 21, 2006

Purpose: The purpose of this teleconference is for members of the Hypoxia Advisory
Panel's Subgroup #2 to discuss each panelist's progress toward addressing their
assignments related to the current understanding of nutrient sources, fate and transport
within the Mississippi River Basin and delivery to the Gulf of Mexico.

Attendees: Subgroup Leader:
HAP Members:

HAP Chair:
SAB Staff:

Dr. Judy Meyer

Dr. Walter Boynton
Dr. William Crumpton
Dr. Mark David
Dr. Robert Howarth
Dr. Richard Lowrance
Dr. Kyle Mankin
Dr. Kenneth Reckhow
Dr. Andrew Sharpley

Dr. Virginia Dale

Dr. Tony Maciorowski
Dr. Tom Armitage
Dr. Holly Stallworth
David Wangsness (USGS)

Others Present: James Baker, IA State University

Dean Lemke, IA Dept. of Ag. & Land Stewardship

Don Perish, American Farm Bureau

Dennis McKenna, IL Department of Agriculture

Meeting Summary: The discussion followed the issues and timing as listed in the
meeting agenda and is summarized below:

Overview of "Lessons Learned" at Mpls Fate/Transport Symposium:

Those who attended the "Science Symposium: Sources, Transport, and Fate of
Nutrients in the Mississippi and Atchafalaya River Basins" in Minneapolis, MN during
the period November 7-9, 2006 agreed that there were many updates that will be useful to
this review. Much of the discussion revolved around the new nutrient flux estimates

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provided by Bill Battaglin (USGS) and, particularly, the need for the panel to fully
understand the new procedure being used to estimate nutrient flux, and to fully
understand how much of the difference between the values used in the initial assessment
and current values are real changes or trends in nutrient flux, and how much is due to the
use of a new procedure to estimate flux. The USGS recently posted documentation of the
new procedure at: http://toxics.usgs.gov/hypoxia/ and will provide further information
during the HAP meeting in December. Bill Battaglin's presentation at the Minneapolis
meeting is also available on the Symposium web site at: http://www.tetratech-
ffx.com/nutrient fate symposium/agenda.htm. There was additional discussion of
information presented, such as results of current SPARROW modeling and the current
understanding of P as a limiting nutrient, that resulted in the formulation of several of the
questions discussed in greater detail later during the call, and are reflected in the attached
list of questions to invited speakers at the December meeting.

Discussion of Draft Outline Responses to the Charge:

Temporal Character of Loads/Fluxes (Part 2.A.D:

Prior to the call, there was little or no new information on point sources available
to the panel. During the call, Katie Flahive (EPA/OWOW) delivered the MART report
"Reassessment of Point Source Nutrient Mass Loadings to the Mississippi River Basin",
which was distributed to the panel for their review, and will be discussed further at the
December meeting.

A new model for estimations of atmospheric deposition suggests that N
deposition in the Ohio River basin is higher than previously estimated, by as much as
50%, but that atmospheric deposition still is not a significant source of N.

There were several questions/comments related to the USGS flux estimates that
are reflected in the attached list of questions and will be addressed further at the
December meeting.

It was pointed out that seasonal (May/June) N03 loads are directly related to
hypoxia but that P is released over a 1-2 year period on the shelf and, therefore, it is more
important to consider annual loads for P.

It also was pointed out that Battaglin presented information on trends that were
based on 5-year running averages, largely because the original assessment report set the
time period, but the group feels that they should look at trends based on flow-adjusted
annual loads.

It was clarified that "total load" to the Gulf of Mexico means the sum of the loads
from the Mississippi and Atchafalaya Rivers.

Mass Balance (Part 2.A.ii):

Dr. David is redoing the mass balance assessment from the initial assessment, but
will cover the period 1996-2005. He noted that it appears that fertilizer applications have
remained fairly constant while crop yields have increased recently, which should result in
a decreasing trend in nutrients. At this time, nutrient mass balance (N & P) is not well

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understood and requires further research and discussion - see questions for December
meeting.

Discharge from tile drains is poorly understood, yet much of the poorly-drained
glacial till in the Midwest is underlain by tile drains. Often as much as 50% of an area
(lowlands) can be drained by tiles, while much of the runoff from the uplands also enters
the drains when the water reaches the lowland areas.

Manure, as a source of nutrients, was not treated effectively in the first assessment
but needs to be addressed in this review. However, estimates that compare manure and
fertilizer as sources of N & P vary widely, and there appears to be very limited
information on application rates and timing of fertilizer at the watershed scale, and
similar information on manure is fairly unknown.

Transport. Transformations. Sources. & Sinks (Part 2.A.iii):

There was much discussion of denitrification and how it can be significant at
lower flows, but that the majority of the nutrient mass is transported during high flows
when in-stream processes can't keep up with the supply. Extending the retention times in
reservoirs, backwater areas, floodplains, wetlands, etc. will increase denitrification but, at
the same time, the production of N20 or N2 may be an important contribution to
greenhouse gases and, therefore, needs to be better understood as measures are
introduced to increase denitrification. Wetlands can control nitrogen losses if managed in
a way to allow for wet/dry cycles.

There appears to be little information on denitrification in large river systems.
What is available is mostly model derived, and ranges of values are quite large. For this
review, it is important to be able to set some upper and lower limits for nitrification and
denitrification to be able to evaluate the effects on the total mass balance.

Mark David will attend a workshop on denitrification during the week of
November 27.

There does not appear to be much net exchange (sorption/desorption) of P in the
river system, but desorption occurs as the plume becomes more salty (approximately 10%
of the load on the time scale of hours to days) and the remainder can desorb from the
sediments on the time scale of years.

There was further discussion of fertilizer and manure application rates, timing,
and form; the relation between the reduction of nutrients and the potential loss of soil
organic matter (will it result in a negative N balance); the effect of modifying cropping
systems; and the need to better understand the range of inputs at the watershed scale
rather than State averages - all of which helped to formulate questions to the technical
presenters at the December meeting (see below).

Predicting Nutrient Delivery to the Gulf (aPrt 2.B.i). and
Routing & Transport Processes from Source to Gulf (Part 2.B.ii):

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Information provided at the Minneapolis Symposium and presentations scheduled
for the December SAB meeting will contribute to the understanding of the ability of
current models to address these issues.

Discussion of Questions for Invited Experts at December 6-8 Meeting:

Discussion throughout the conference call, and additional input following the call,
evolved into the following questions to several of the technical experts scheduled to make
presentations related to their areas of expertise, and to participate in roundtable
discussions with the panel.

Questions/Comments to USGS Concerning New Load/Flux Estimates:

1.	Given that the large river nutrient concentrations change slowly, has
consideration been given to interpolating concentrations rather than model fitting? Would
interpolated values be a better representation of flux in a given year compared to model
fitting?

2.	The number of monitoring sites has decreased since the initial assessment.
Please provide a list and/or map of the changes.

3.	We understand that the Action Plan called for the estimation of 5-year moving
averages, but have you looked at decadal trends and/or annual trends, which may provide
a different picture than the 5-year moving average?

4.	What nutrient trends do the current analyses indicate, and what is the current
explanation?

Questions/Comments to USDA on CEAP:

1.	What are the most relevant and up-to-date reports on conservation activities
that would contribute to an understanding of nutrient sources, fate, and transport within
the Mississippi River system?

2.	We understand that summary reports are being prepared by each of the
benchmark watersheds within the MRB for review in early 2007. Are there early drafts
available that could provide some background on current conservation practices, their
numbers and locations, their effectiveness at reducing nutrient loads to surface and
ground water, and any preliminary mass balance calculations?

Questions/Comments to Modelers:

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1.	Please comment on the model's strengths and weaknesses for addressing HAP
charge-related questions at the MSB and Gulf of Mexico scale. At what scale is the
model most applicable? And what is your level of confidence if it is scaled up or down?

2.	What are the error estimates and uncertainties associated with the model?

3.	Some of the current models appear to have questionable accuracy in predicting,
at small and intermediate-scales, the potential nutrient (total N, total P, inorganic N,
inorganic P) transport/delivery to flowing streams and major tributaries. Dr. David Mulla
- at the recent Nutrient Source, Fate and Transport Symposium in Minneapolis, MN -
illustrated strengths and weaknesses and the possible benefits of identifying critical
source areas using appropriate small and intermediate-scale models. Dr. Mulla also
showed a slide which indicated that a 40 percent increase in precipitation had contributed
to a 245% increase in water discharge over a 50-year period. With these observations in
mind:

a.	Could/should the approach(es) illustrated by Dr. Mulla in his presentation in
Minneapolis, MN be used throughout the Mississippi River Basin to more
accurately identify critical "source" areas, to guide management changes to
reduce specific nutrient (N and/or P) loss, especially during critical discharge
periods (early spring: April-May) 	in targeted areas within the Basin?

b.	Considering the costs already associated with educational efforts, and costs
associated with some local and state nutrient regulation implementation, what
would the costs/benefits be of conducting such modeling before any further
national policy development or implementation?

4.	Comment on plans and/or opportunities for improvements in the model - and,
is the timing such that the outcomes will contribute to this review?

5.	We understand that SPARROW is being updated from 1992 to 2002
agricultural and land cover data for the calibration year. What are the limitations of fewer
monitoring data during 2002 for calibration? And, are denitrification estimates being
updated?

6.	Any information on the ability of SWAT to simulate conservation practice
effects on N and P transport would be helpful. More specifically, to what extent is SWAT
being used to address/simulate the effects of tile-drain management alternatives, drain
spacing, manure application as a nutrient source, and stream buffers?

7.	How would you recommend we resolve any scale issues regarding basin-wide
assessments, which are based on using your model at an inappropriate scale for which it
was developed?

8.	Is there any way of using SWAT to spatially link processes / losses occurring in
different parts of the Basin, but which influence Gulf inputs?

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9. The new load estimates for the Mississippi River basin differ from earlier
estimates, primarily because of a new procedure being used to calculate the loads. What
are the implications of this for the hypoxia models that have been run to data?

Questions on N & P Management Approaches:

1.	Please be prepared to discuss the effectiveness, applicability, and potential
impact of current and emerging management practices including drainage management,
cropping systems (cover crops, perennials, living mulches, relay crops, etc.), and infield
nutrient management (timing, application rate, etc.).

2.	Please provide your perspective on the watershed study published in JEQ in
2004 where the authors showed that changing from fall NH3 application to use of the late
spring nitrate test (LSNT) led to changes in nitrate loads from the treated watershed
compared to the control watersheds. What is the magnitude of the potential changes if
this approach is widely used?

3.	Across the cornbelt, it appears that fertilizer application rates have been
relatively constant and crop yields have dramatically increased in recent years, leading to
small N balances. River nitrate concentrations should be declining now or soon,
depending on system lags. Can you comment on these recent changes and the potential
for stream nitrate concentrations in the upper Midwest to decline in response?

4.	Fertilizer use is based on averages of state sales data, and manure application
rates are fairly unknown. At the watershed scale, most information is from surveys, and
these data are generally very limited spatially. What would you suggest as sources of
information on fertilizer and manure application rates, timing, and locations at a
watershed scale? Given that surveys can't be done everywhere, what is the best way to
make reasonable estimates of both?

5.	How well do we understand the source distribution, timing and, therefore, the
nutrient mass balance associated with manure?

6.	What is new in manure management over the past several years, and are there
any data suggesting that manure management has resulted in any related improvements in
water quality?

7.	What is the current understanding of the effects of modifying cropping systems
to reduce nutrient loss as opposed to further reducing fertilizer/manure application rates?

8.	What is known about the consequences of potential reductions in fertilizer
application rates to soil resource sustainability? Given the high yields of the past five
years and steady fertilization rates, is it likely we are reducing soil organic N pools in the
cornbelt? If so, what are the biophysical mechanisms that would cause this?

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9.	Please comment on drainage management in general, the use of denitrification
reactors around and at the end of tile drain lines, and other options being considered that
would alter drainage management to improve water quality while maintaining drainage.

10.	What is known about the potential for drainage management in the Des
Moines lobe?

11.	If P mainly drives Nutrient Management Planning (NMP) in the upper basin
where there is a concentration of livestock operations and local water quality issues are
freshwater driven, while N drives NMP as one gets closer to the Gulf, are there any
efforts to coordinate management of N & P within the Basin as a whole? This may be an
issue as P-driven management could have little or no effect on N loss reduction (may
even increase N loss) and vise-versa. In other words, is there a plan to marry short-term
NMP strategies with long-term goals and impacts?

12.	As market forces impact the construction of ethanol and biodiesel production
facilities, and as farmers change their cropping systems to take advantage of these
energy-based crop markets, what is the potential impact of these market forces on
nitrogen and phosphorus use in the Mississippi River Basin? Is nutrient ( N and/or P)
discharge to the Mississippi River (and to the Gulf of Mexico) likely to change as a result
of these market forces, and if so how much for each nutrient?

13.	In some states, farmers are required to prepare and submit nutrient
management plans before the application of manure nutrient resources to individual farm
fields (e.g Regulation 5 in Arkansas for liquid manures). In other states, before nutrients
from fertilizer, manure, and/or biosolids can be applied to farm fields, approved nutrient
management plans are required (e.g. Neuse River and Tar-Pamlico River Basins in North
Carolina).

a.	Would mandatory nutrient management plans for all farm fields in the
Mississippi River basin be a cost-effective means to significantly reduce nutrient (N
and/or P) discharge to local water resources, the Mississippi River and, ultimately, the
Gulf of Mexico?

b.	Are agricultural policies in place, or could/should practical and straightforward
policies be developed, to provide economic incentives to farmers to prepare AND
implement nutrient management plans in the entire Mississippi River basin?

All questions have been forwarded to the respective speakers with a request that
they consider them while preparing their presentations, but also be aware that additional
questions will likely develop during the roundtable discussions.

Review of Action Items & Assignments:

Dr Meyer and Dave Wangsness agreed to draft a list of questions for the
December meeting and circulate it to the subgroup for additions and comments. That
process resulted in the above list.

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Dr. Meyer requested that each subgroup member provide her with a few bullets
describing their work to date by December 1 so that she can incorporate them into a brief
overview of Subgroup 2's progress report for the December meeting.

Respectfully Submitted:	Certified as True:

/Signed/	/Signed/

David J. Wangsness	Dr. Judith Meyer, Leader

Designated Federal Officer	Hypoxia Advisory Panel — Subgroup

on Nutrient Sources, Fate, and
Transport

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