Rank year Month — Flow cfs

1 1937 2 1,944,286
2 1973 5 1,850,129
3 1945 4 1,847,500
4 1950 2 1,796,357
5 1973 4 1,774,333
6 1983 5 1,623,290
7 1979 4 1,564,067
8 1975 4 1,561,167
9 1991 1 1,509,323
10 1949 2 1,500,250
ant 1945 3 1,494,129
12 1997 3 1,469,545
13 1984 5 1,457,645
14 1950 3 1,414,194
15 1944 5 1,391,710
16 1943 6 1,382,933
17 1974 2 1,379,893
18 1979 3 1,375,097
19 1962 4 1,368,000
20 1939 3 1,366,774
Page 30 The second paragraph suggests that the Gulf of Mexico is comparable to other

water bodies including the Kattegat, the Baltic and Adriatic Seas. This is further reinforced by
Figure 4.2, Comparative Evaluation of Fishery Eco-systems Response to Increasing Nutrient
Loading. As we pointed out in our August 9, 1999 comment letter on the six Topic Reports,
page 26, “What the authors failed to acknowledge is that the Gulf of Mexico is an open, highly
dynamic system compared to other water bodies such as the Black Sea and Baltic Sea.” This
section also seems to imply that hypoxia is strictly a man-made problem when there are
significant hypoxic areas in oceans as a result of natural conditions.

Pages 30 and 32 should include language that acknowledges the above and that notes the
reference Figure 4.2 is a theoretical possibility, not a forecast of what may actually happen in the
Gulf of Mexico. Please go back and reread the Topic 2 Report regarding the shrimp and fish
catch.

Concluding remarks:
Our hope would be that the integrated assessment would acknowledge that there is an extremely

limited knowledge base insofar as the cause and, therefore, the possible remedies to the hypoxic
zone in the Gulf of Mexico.



Recent data presented by US.G.S.3 show a very strong correlation (R? between 0.86 to 0.93)
between the size of the hypoxic zone and the flux of nitrate and streamflow during the May —
June time period of each year. While there are many factors involved in gulf hypoxia, this adds
further credence to the idea that experiments should be conducted on reducing the rate of
streamflow diversions of Mississippi River water into the Atchafalaya River in order to reduce
the amount of nutrients introduced into the area of the Gulf of Mexico that is most likely to foster
hypoxic conditions.

With the exception of June of 1943, the top 20 mean monthly flows of the Mississippi River at
Vicksburg between 1931 and 1997 have occurred in January through May. None of the floods of
1993 even make the top twenty in terms of average monthly flows. The levees protecting New
Orleans are designed to handle flows of 1.25 million cfs. The Bonnet Carre Diversion structure
above New Orleans can move 250,000 cfs into Lake Ponchartrain. From looking at the table
below, it would appear that since 1931, average monthly flow of the Mississippi River at
Vicksburg would have exceeded the average design flow of the Mississippi River below Baton
Rogue in only 10 of the 804 months. This means that unless some really extreme flow event
occurred, more that 98 percent of the time it would be physically possible to test the theory of
putting the entire flow of the Mississippi River up to 1.5 million cfs, out through the birdsfoot
delta below New Orleans (1.25 million cfs) and Lake Ponchartrain (250,000 cfs if necessary)
especially during Januray- June when the bulk of the nitrate flux occurs. (See Figure 1, Project
Design Flood. Please include in the Final Integrated Assessment report.)

While current law mandates that a significant portion of the Mississippi River flow be diverted
into the Atchafalaya River, it is physically possible to close the Old River Diversion and not
allow any water from the Mississippi River to reach the Atchafalaya River. It also will surprise
most people to know that under the design flood, 1.5 million cfs would be flowing out the
Atchafalaya River, but only 1.25 million cfs would being flowing out the Mississippi River past
New Orleans. Again, these facts need to be spelled out very clearly in the final IA so that
policymakers can consider all the options, otherwise both the CENR reports and the Integrated
Assessment will have failed to address the initial charge of P.L. 105-383 which calls for
examination of “...methods of reducing nutrient loads...” and its development of a plan of action
to reduce, mitigate and control hypoxia in the northern Gulf of Mexico.

Mean Monthly Flow of Mississippi River at Vicksburg between 1931-1997:

3 Presentation by Don Goolsby, at Gulf Hypoxia Science Meeting, December 3, 1999 in St. Louis, MO.



As representatives of the farmers and ranchers who occupy and farm much of the land in the
MRB, we look forward to the opportunity to work with others on trying to resolve the many
issues involved with the hypoxia zone in the Gulf of Mexico. However, we are strongly of the
opinion that this needs to be a joint effort along with other parties that have also had an impact
on the hypoxic zone.

Sincerely,

2

Richard W. Newfher
Executive Director
Washington Office



Pa
AMERICAN FARM BUREAU FEDERATION’

226 TOUHY AVENUE * PARK RIDGE + ILLINOIS + 60068 + (847) 685-8600 + FAX (847) 685-8896
600 MARYLAND AVENUE S.W. + SUITE 800 + WASHINGTON, D.C. + 20024 + (202) 484-3600 + FAX (202) 484-3604
Internet: http://www.fb.com/

December 17, 1999

Gulf of Mexico Hypoxia Working Group

National Oceanic and Atmospheric Administration
National Centers for Coastal Ocean Science
Room 9127

11305 East-West Highway

Silver Spring, MD 20910

Re: | Comments on Integrated Assessments of Hypoxia in the Northern Gulf of Mexico

As we indicated in our previous comments on the six Topic reports, a significant number of the
American Farm Bureau Federation’s five million members live and farm within the Mississippi
River Basin. We appreciate the opportunity to respond to the Integrated Assessment by the
National Science and Technology Council’s Committee on Environment and Natural Resources
(CENR).

In looking at the draft Integrated Assessment report, we note that there have been a number of
changes from the original six Topic reports. We assume these changes were based on the
comments previously forwarded by AFBF and others about the six Topic reports. We are also
aware that there have been some meetings since the Integrated Assessment report was issued that
offered opportunity for input, the December 3rd meeting in St. Louis being one example.

While we appreciate the opportunity for the ongoing dialogue, we have a growing concern as this
process continues. It appears that the entire CENR evaluation has focused on nutrients as being
the cause of the hypoxic zone in the Gulf of Mexico from the beginning to the end of this
process. Specifically, the effort seems to be aimed at nitrogen fertilizer.

While nitrogen fertilizer may well be one of the causal factors involved in the hypoxia zone in
the Gulf of Mexico, the focus and emphasis on nitrogen may have been so narrowly defined that
other important factors have or will be overlooked. A couple of examples are:

1. The hydrology of the Mississippi River Basin (MRB) has changed enormously over the
past 122 years. When James Buchanan Eads built the first jetties to stabilize the channel
of the Mississippi River, he started one of the biggest changes in the hydrology of a large,
natural drainage body ever accomplished by mankind on the face of this earth. It has had
far-reaching repercussions; many of which would judge to be good and some would
argue to be less desirable, to the MRB and the land, people and economy involved.



While the integrated assessment does give some acknowledgement of these changes,
there are vast gaps of knowledge regarding how these changes might affect the hypoxia
zone in the Gulf of Mexico. While we will subsequently go into greater detail, one quick
example is the fact that currently, about 22% of the water in the Mississippi River is
diverted to the Atchafalaya River, routing these waters onto shallow coastal shores where
the hypoxia zone has subsequently developed on a regular basis.

2. Other factors such as the carbon issue have been discussed at some length. Although we
would concur that this may not be a major factor, our view is that waterflow and the
disbursement of the flow are probably the most important variable, the carbon issue still
needs more study.

While the integrated assessment attempts to draw a simple picture of the causes, consequences
and cures for hypoxia, a close reading reveals a more complicated scenario. In fact, there are
many factors that play a role in the incidence and extent of Gulf hypoxia. An action plan that
deals with one factor — nutrient enrichment — and that places the burden of reducing that factor
on one segment of the economy — agriculture is unlikely to significantly reduce Gulf hypoxia.

Following are our more specific/technical comments:
Page 8 of the draft integrated assessment clearly focuses on nutrients and states:

“reductions in total nitrogen flux of about 40 percent are necessary to return to loads
comparable to those before the large increases in 1950-1970.”

In the final IA, this particular sentence needs to read as follows:

“reductions in total nitrogen flux of about 40 percent are necessary to return to loads
comparable to those between 1955-63 before the large increases in 1963-1983.”

The need for this sentence to be clarified is contained in Figure 2.4 of the draft Integrated
Assessment. The chart in Figure 2.4 shows that data on nitrate flux does not start until 1955 and
information on organic nitrogen does not start until 1973. The same chart also shows that the low
point in nitrate flux occurred in 1963 and increased to a peak in 1983 before declining.

It appears from the sentence, as quoted in the Draft IA, that the 40% reduction is being compared
to total nitrogen loads in the 1940s- for which there is no data. That same sentence also states
that the large increases in total nitrogen flux occurred in 1950-1970 which the graph in Figure
2.4 of the IA clearly contradicts by showing that the large increase in nitrate flux occurred
between 1963 and 1983.

Page 8 of the draft-integrated assessment also continues by stating:
“Model simulations indicate that nutrient load reductions of 20-30% would result in a 15

to 50% increase in bottom water dissolved oxygen concentrations and a 5 to 15 %
decrease in surface chlorophyll concentrations. Such increases in oxygen are significant



in that they represent an over all average for the hypoxic zone and that any increase
about the 2 mgf threshold will have a significant effect on marine life.”

Our comment about this section is that, in fact, the quickest way to test the nutrient enrichment
theory is to suspend all diversion of Mississippi River flow into the Atchafalaya River, which
consequently goes directly into the center of the hypoxic zone. That will immediately reduce the
flux of both nitrate and total nitrogen that moves into the hypoxic zone from the Mississippi
River by 33.9 percent.',? This fact needs to be included in the integrated assessment so that

policymakers can consider all the options.

Current_MS River Flow is Split 22% to Atchafalaya River and 78% Through New Orleans

TOTAL
TotalNto |TotalNto [Nitrogen to
Hypoxic Other Parts |Gulf from
Zone of Gulf MS R Basin
(Mition — (Million ‘| (Million
Metric Tons) |Metric Tons) |Metric Tons)
MS R. Total N to Deep Water (1.6 x 78% x50%) 0.624)
MS R. Total N_ to Non-Hypoxic Zone (1.6x 78% x 50 % x 40%) 0.2496)
MS R. Total N to Hypoxic Zone ((1.6 x 78% x 50% x 60%) 0.3744
Total N to Hypoxic Zone from MS R. to Atchafalya R. (1.6 x 22%) 0.352
Subtotals 0.7264 0.8736
TOTAL 1.6]
Assume 100% of MS River Flow goes through New Orleans and None is Diverted to Atchafalya River
MS R. Total N to Deep Water (1.6 x 50%) 0.8
MS R. Total N_ to Non-Hypoxic Zone (1.6 x 50%x 40%) 0.32)
MS R. Total N to Hypoxic Zone (1.6 x 50% x 60%) 0.48 _.!
Subtotals 0,48 1,12}
TOTAL 1.6]

The benefit to the hypoxic zone of keeping 100% of the flow of the Mississippi River in the

Mississippi River channel and routing it through New Orleans and out the birdsfoot delta into
deep water is that it would reduce the amount of total nitrogen moving into the hypoxic zone

from the Mississippi River by 33.9% (0.0.7264- 0.48)/0.7264* 100)

' 50% of MS River flow and nitrogen is lost to deep water in the Gulf of Mexico and 40% of
the remaining 50% of the flow and nitrogen of Mississippi River exiting out of birdsfoot delta
south of New Orleans never make it to the hypoxic zone. Based on unpublished paper dated
November 29, 1999, prepared by Donald F. Boesch, University of Maryland Center for

Environmental Science for Gulf Hypoxia Science Meeting.

? Diversion of Mississippi River flow into the Atchafalaya River is based on the formula: Flow
diverted from MS River = (30% x(Flow in Red River + Flow in Mississippi River)) - Flow in

Red River. Currently, based on this formula, about 22% of the Mississippi River flow gets
diverted into the Atchafalaya River. Personal communication with Chuck Shadie, Corps of

Engineers, New Orleans District.