19910326 Ver 1_More Info Received_19940601

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i S IM., -UWIT TES.°ENVIRONMENTAL PROTECTION AGENCY
PROAt016 R E G ION I V
345 COURTLAND STREET. N.E.
JUN 1 1994 ATLANTA, GEORGIA 30365
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WATEF' MAY 2 4
MAY 81 1994
WilminyW'h District, Corps'of Engineers
P.O.` Box 1890 DIV. Of 1 NV1RG%MEWA!- + fwd :
Wilmington, NC 28402-1890 DMECToRs.oFF CE
ATTN= Mr. Charles Wilson
Subject: Environmental Assessment (EA) for the Aquatic Plant
Management Program in Lake Gaston, NC/VA
Dear Colonel Cajigal:
21
Pursuant to Section 309 of the Cle Act, EPA, Region IV
has reviewed the subject document which uates the
environmental consequences of the Wilmington District's aquatic
plant.contr Gaston. These measures are a
sponse to expanded coverage of y illa and its anticipated
colonization of other Corps of Engineers-impoundments such as
John H. Kerr Reservoir. In addition to the problems with the
Hydrilla, populations of other non-native species, viz.,
Watermilfoil and Brazilian elodea, have the potential to
increase to problem levels. In the absence of control measures
experience demonstrates that navigation, recreation, and water
supply uses can be adversely affected by the robust growth of
these plants.
A number of control alternatives applied singly and in
combination are presented in the document, i.e., water-level
manipulations, herbicide application, and assorted
biological-mechanical-physical measures. The no-action option
is also included.as a basis of comparison. While all control
categories have some merit in specific situations, the judicious
manipulation ofwater levels is our option of choice. On the
other hand, use of EPA registered herbicides (diquat, endothall,
fluridone, and copper formulations) continues to be deemed the
most cost-effective management tool by most reservoir managers.
The use of innovative measures which do not involve
herbicides also appears to have promise. Although EPA
encourages pursuit of such methods, caution is necessary
regarding the employment of exotic herbivores/pathogens to
reduce weed species to insure that unanticipated problems are
not created. Additional assessment will be necessary before any
definitive determination can be made regarding more wide-spread
use of these inventive techniques to control undesirable
aquatics.
The major area of EPA's concern regarding the "balanced
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A
control program" discussed in the EA focuses on its use of
herbicides in the aquatic environment. In this regard a
relatively comprehensive examination of previous research on the
significant consequences of aquatic herbicide use was provided
in a recent environmental impact statement (EIS) prepared by the
Tennessee Valley Authority (TVA). We have not investigated the
original studies and/or the basis of the assumptions made
therein; however, we acknowledge that the data cited in the EIS
suggest that registered herbicides appropriately applied do not
cause unacceptable consequences to either public health or the
natural environment.
This notwithstanding, TVA's experience over the last twenty
years in its reservoirs has lead to development of integrated
control techniques. This has become the industry standard and
relies less on routine, maximum permissible herbicide spraying
to a more measured approach which takes into account individual
circumstances of the target site. Namely, the factors which
influence the growth/extent of aquatic vascular plants are
assessed and control techniques applied accordingly.
EPA believes that herbicide applications should be
proscribed to those situations in which there are no other
practicable alternative(s). However, we have reservations to
the aerial application of herbicides using _he i.copter mounted
equipment. Even when this is an approves app ica ion que
specified on the label and not restricted by the involved state
regulatory agencies, there is still concern on our part that
non-target wetland species would be exposed. Low-drift nozzles
are available to focus application, but we continue to have some
misgivings about this technique. Future documents should
provide observations regarding collateral damage to non-target
species from all application methods. These data would provide
a basis of comparison to make a more reasoned judgment of
expected similar actions and could be a part of the overall
monitoring program implemented to determine potential water
quality impacts from herbicide use.
Given the long-term unknowns associated with herbicide use,
we suggest that the Wilmington District continue to
evaluate/ f-?fficacy and impacts associated with all
noted_ eradication-options. The resu conclusion therefrom
c uld provide a more quantitative appraisal of their impact(s)
as the program undergoes future revision.
While beyond the scope/analysis of this particular document,
the increasing amount of nutrients entering piedmont lakes via
non-point source runoff (NPSR) is a major element in fostering
the growth of aquatic vegetation.__ In future documentation we
suggest that the Corps provide an assessment of this nutrient
influence together-w-ith--en-appraisa o how effective
stringently applied NPSR control measures would be in reducing
exotic plant infestation and attdndant herbicide use.
Thank you for the opportunity to comment. If we can be of
further assistance, Dr. Gerald Miller (404-347-3776) will serve
as initial point of contact.
Sincerely,
,L- -a"
Heinz J. Mueller, Chief
Environmental Policy Section
Federal Activities Branch