Northern Prairie Wildlife Research Center
Effects of a Legal Drain Clean-Out on Wetlands and
Waterbirds: A Recent Case History
By:
Gary L. Krapu*
Abstract: Repairs to legal drains in the United States may be
regulated to protect adjacent wetlands under Section 404 of the Federal Water
Pollution Control Act, commonly known as the Clean Water Act (CWA). However,
few studies have examined effects of legal drain clean-outs on adjacent wetlands
and associated migratory waterbird populations. I compare water regimes, cover-to-open
water ratios, and waterbird use on Bruns, Big, Meszaros, and Kraft sloughs (BBMK)
in Sargent County, North Dakota before and after the clean-out of Crete-Cogswell
Drain No. 11, and relate wetland habitat loss to observed disease-related mortality
among staging waterfowl in fall 1990 and spring 1991. Water regimes of BBMK
were exceptionally stable, with few records of drawdowns before 1984 when the
clean-out began. After the clean-out (1987-90), BBM were dry by mid-summer in
all years and open area declined by 96% by 1990, whereas Kraft Slough (a control
area) had water throughout all years and percent open area did not change. Numerous
species of waterbirds nested in BBMK before the clean-out, and mean ranks of
waterbird density were similar. After the clean-out, waterbirds failed to breed
successfully in all years at BBM, and use as major waterfowl staging areas and
for waterfowl hunting also ended. At Kraft Slough, use by breeding and staging
waterbirds continued in all years, as did waterfowl hunting. Reduced access
to fresh water after the Drain No. 11 clean-out may have contributed to a dieoff
of 487 lesser snow geese (Chen caerulescens) from necrotic enteritis
in Kraft Slough in November 1990. Loss of three major staging areas in Sargent
County as a result of the drain clean-out has further concentrated migrant waterfowl,
particularly during drought periods, increasing the magnitude of risk when epizootics
occur in southeastern North Dakota. Ducks and geese banded in Sargent County
have been recovered from 34 and 14 states, 7 and 6 provinces of Canada, and
13 and 1 other countries, respectively, indicating waterfowl populations from
a wide area are potentially vulnerable to epizootics when crowded into limited
roosting habitat. Despite causing the loss of wetland habitat for thousands
of midcontinent waterfowl and other waterbirds, a Federal Court in North Dakota
ruled that the clean-out of Drain No. 11 met the criteria necessary to be considered
maintenance under Section 404 clause (f)(1)(c) and was not recaptured under
clause (f)(2). This outcome suggests current law does not protect wetland functions
needed to support migratory waterbird populations or associated recreational
values when sites have become naturally restored through lack of maintenance
of legal drains.
Key Words: Avian cholera, cumulative effects, diving ducks,
drain clean-outs, epizootics, geese, legal drains, necrotic enteritis, prairie
pothole region (PPR), Section 404, waterbirds, water/cover ratios, waterfowl,
wetland complexes, wetland functions
This resource is based on the following source (Northern Prairie Publication
0960):
Krapu, Gary L. 1996. Effects of a Legal Drain Clean-out on Wetlands
and Waterbirds: a Recent Case History. Wetlands 16(2):150-162.
This resource should be cited as:
Krapu, Gary L. 1996. Effects of a Legal Drain Clean-out on Wetlands
and Waterbirds: a Recent Case History. Wetlands 16(2):150-162.
Jamestown, ND: Northern Prairie Wildlife Research Center Online.
http://www.npwrc.usgs.gov/resource/wetlands/case/index.htm
(Version 17FEB2000).
Table of Contents
*National Biological Service, Northern Prairie Science Center, 8711 37th Street,
Jamestown, ND 58401-9736
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