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I NONPOINT SOURCE SUCCESS STURY
Watershed Improvements Restore and Maintain Water Quality at West
Lake Corning ("City Reservoir")
Wfltprbodv Imnroved Waterquality in West LakeCornins(known iocal|yasthe "Citv
ii"' ^ ' J Reservoir") declined following land use changes in the watershed
in the 1980s and early 1990s, as farmers and landowners converted pasture and grasslands to row
crop production. The land use changes accelerated sheet and rill erosion in the watershed and
the delivery of sediment and nutrients to the lake, which degraded the lake's fishery. As a result,
the lake was placed on Iowa's first Clean Water Act (CWA) section 303(d) list of impaired waters
in 1998 with a siltation impairment. Through the Three Lakes Water Quality Project, farmers and
landowners implemented a series of best management practices (BMPs) in targeted areas of the
watershed, which reduced sediment delivery to the lake and improved water quality. Following the
project, West Lake Corning was removed from Iowa's impaired waters list in the 2006 listing cycle.
Problem
Built In 1915, West Lake Corning is a 13-acre lake
within a 418-acre watershed in southwest Iowa
(Figure 1). Along with Lake Icaria and Binder Lake, it
serves as a public drinking water supply for the city of
Corning, and for regional water supplies in the area.
The three lakes also serve as important regional hubs
for outdoor recreation in southwest Iowa, primarily for
fishing and boating. West Lake Corning is the smallest
of the three lakes.
The Iowa Department of Natural Resources (DNR)
determined through a 1996 CWA 305(b) water qual-
ity assessment that excessive sediment from the
watershed was harming the aquatic life in West Lake
Corning. As a result, the lake was placed on Iowa's
1998 CWA list of impaired waters for not supporting
its aquatic life designated use (using narrative criteria),
based upon the best professional judgement of DNR
Fisheries biologists.
A total maximum daily load (TMDL) analysis for West
Lake Corning was completed by DNR in 2001, funded
through a U.S. Environmental Protection Agency (EPA)
CWA section 319 grant. Using land use data provided
by the Adams Soil and Water Conservation District
(SWCD), sediment loading to the lake was estimated at
579 tons per year.
Implemented BMPs
| Grade Stabilization Structures
Terraces
West Lake Corning
(City Reservoir) Watershed
City of Corning, Adams County. Iowa
Implemented BMPs
Figure % Landowners implemented targeted erosion-
control BMPs throughout the West Lake Corning (City
Reservoir) watershed.
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Table 1. Pre-project and post-project erosion in the
watershed and sediment delivery* to the lake
Before
Project
After
Project
Change
Average sheet and rill
erosion per acre per year
5.79 tons
2.73 tons
-53%
Total sheet and rill erosion
per year
2,565 tons
1,211
tons
-53%
Average sediment delivery
to the lake per acre per year
1.31 tons
0.53 tons
-60%
Total sediment delivery to
the lake per year
579 tons
236 tons
-59%
Figure 2. West Lake Corning now fully supports its
designated uses.
* Estimates based on Predicting Rainfall Erosion Losses, The Revised
Universal Soil Loss Equation, Section I (NRCS 2000) and Erosion and
Sediment Delivery Procedure¦, Section I (NRCS 1998)
Project Highlights
The Three Lakes Project, administered by the Adams
SWCD in Corning, was created in 1996 to implement
BMPs in the West Lake Corning watershed, as well
as in the Lake Icaria and Lake Binder watersheds. It
received primary financial support from the Iowa
Department of Agriculture and Land Stewardship-
Division of Soil Conservation (IDALS-DSC) through
the Water Protection Fund and Watershed Protection
Fund (WPF/WSPF) and from the DNR through EPA CWA
section 319 funding. The project employed a full time
watershed project coordinator to help landowners
implement BMPs in all three watersheds.
With the assistance of the project coordinator,
landowners and farm operators installed five sediment
and water control structures at key locations in the
West Lake Corning watershed, enrolled approximately
40 acres of targeted cropland directly above the
lake in the U.S. Department of Agriculture's (USDA's)
Conservation Reserve Program (CRP) and planted it
in perennial vegetation, built terraces on cropland on
the east side of the lake, and implemented rotational
grazing practices to improve pastureland and reduce
runoff in the watershed.
Results
The BMPs implemented through the project reduced
estimated sheet and fill erosion in the watershed
and sediment delivery to West Lake Corning by more
than 50 percent (Table 1). The reduction In sediment
delivered to the lake improved the lake's water
quality, which in turn improved the fish populations in
the lake. Based on monitoring by DNR Fisheries after
2004, the fish populations were no longer negatively
impacted by siltation and the lake met its aquatic life
designated use. As a result, the lake was removed from
the impaired waters list in the 2006 listing cycle, and
still fully supports its designated uses (Figure 2).
The West Lake Corning fishery has improved since
2008. There has been an increase in the number of
bluegills over 8 inches in length and large bass over
18 inches, according to DNR Fisheries data. In addi-
tion to improvements made in the watershed through
the Three Lakes Project, DNR Fisheries staff added
cedar tree brushpiles to the lake during the winter of
2014-2015 to increase the fish habitat in the lake and
improve angler fishing success. As an example of the
increased number of large bass in West Lake Corning,
DNR Fisheries staff captured a 21-inch largemouth bass
during electrofish sampling in 2015.
Partners and Funding
Project partners providing funding and technical
assistance for the Three Lakes Water Quality Project
included the Adams SWCD, the city of Corning, IDALS,
USDA Natural Resources Conservation Service (NRCS)
and Farm Service Agency, Iowa DNR and private land-
owners. Project funding from public sources totaled
$1,431,790: $813,110 from IDALS WPF/WSPF, $80,036
from IDALS Genera! Fund, $245,281 from EPA CWA sec-
tion 319 (via Iowa DNR), $259,005 from Iowa Publicly
Owned Lakes Program, and $34,358 from USDA NRCS
Environmental Quality Incentives Program. (The total
contribution from private landowners is not available).
* ^ '
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*1 PRO"^
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U.S. Environmental Protection Agency
Office of Water
Washington, DC
EPA 841-F-16-001T
September 2016
For additional information contact:
Bob Waters, Regional Basin Coordinator
Iowa Dept. of Agriculture and Land Stewardship
712-336-3782 • Bob.Waters@iowaagriculture.gov
Steve Hopkins, Nonpoint Source Coordinator
Iowa Dept. of Natural Resources
515-725-8390 • Stephen,Hopkins@dnr.iowa.gov
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