NONPOINT SOURCE SUCCESS STORY
Restoration Reduces Algae and Restores Fishery in Viking Lake
Waterbody Improved
Runoff from private farmland, gully erosion from state park land,
and failing septic systems contributed excessive sediment,
nutrients and bacteria to Iowa's Viking Lake. As a result of these pollutants, Viking Lake was placed
on the Clean Water Act (CWA) section 303(d) list of impaired waters in 2004 for excessive algae and
in 2006 for bacteria. Between 2005 and 2008, the Montgomery Soil and Water Conservation District
(SWCD) worked with federal and state partners to install erosion control structures on private and
state land, upgrade failing septic systems and complete in-lake improvements, including shoreline
stabilization and fish habitat structures. As a result of these projects, lake algae levels decreased and
the fish populations increased, leading to the removal of Viking Lake's algae impairment in 2014.
Problem
Viking Lake, a 137-acre constructed lake in Viking Lake
State Park, drains a 2,181-acre watershed in southwest
Iowa's Nodaway River basin (Figure 1). Viking Lake State
Park is one of southwest Iowa's most popular outdoor
recreation destinations due to its proximity to the
Omaha-Council Bluffs metropolitan area and the sheer
beauty of the area.
In the early 2000s Viking Lake experienced declining
water quality caused by dense algal blooms. Routine
annual lake monitoring by the Iowa Department of
Natural Resources (DNR), beginning in 2000, showed
that Viking Lake ranked 19th highest of the 131 Iowa
lakes tested for chlorophyll a concentrations (indicat-
ing high algae levels). Dense algal blooms at the lake
shaded out rooted aquatic plants, an important habitat
for fish. This degraded habitat led to poor fish growth
and high juvenile fish mortality, which in turn caused an
unbalanced fishery with few quality fish for anglers.
Viking Lake (Waterbody: IA 05-NOD-00930-L _ 0) was
first listed on Iowa's CWA section 303(d) list of impaired
waters in 2004 for not supporting its primary contact
recreation use due to aesthetically objectionable condi-
tions caused by excessive algae, which was fueled by
phosphorus in the lake. The algae impairment was based
on data collected between 2000 and 2002 showing a
chlorophyll a Trophic State Index (TSI) of 68, which is
above Iowa's TSI impairment threshold of 65. TSIs pro-
vide a method for quantifying the productivity and water
quality of lakes as evidenced by phosphorus, chlorophyll
a, and Secchi depth (a measure of water clarity). High
TSIs indicate more productive (eutrophic) lakes, whereas
lower TSIs indicate less productive (mesotrophic or oligo-
trophic) lakes. Viking Lake was also listed as impaired for
high indicator bacteria levels (Escherichia co/i) in 2006.
Figure 1. Numerous best management practices
were implemented in southwest Iowa's Viking
Lake watershed.
Project Highlights
In 2005 the local SWCD and U.S. Department of
Agriculture (USDA) Natural Resources Conservation
Service (NRCS) staff conducted a detailed watershed
assessment that indicated approximately 4,653 tons
of sediment per year was being delivered from the
watershed to the lake. Phosphorus adsorbed to this
sediment contributed to the eutrophication impairment
of Viking Lake. Estimated phosphorus delivery to the
lake from sheet and rill erosion was 1,077 tons per year.
Sediment delivery from gully erosion was estimated at
3,576 tons per year.
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Figure 2. Water clarity before (left) and after (right) completion
of restoration projects.
To address the sediment and nutrient sources, an
Iowa Department of Agriculture and Land Stewardship
(IDALS) project coordinator (based out of the
Montgomery SWCD) worked with landowners to install
erosion control practices, including five grade stabi-
lization structures, 4,400 feet of terraces, seven water
and sediment control basins, two sediment basins, and a
livestock heavy use protection area on private land in the
watershed. To address sediment sources in the state
park (including 22 gully erosion sites), project partners
installed 32 restoration practices, including grade
stabilization structures, water and sediment control
basins, wetlands, and a gabion basket drop con-trol
structure (Figure 1). Additionally, the Montgomery
County Conservation Board (CCB) installed one grade
stabilization structure and the Iowa Department of
Transportation (DOT) stabilized four road culverts.
The Page 1 Rural Water District (now Southwest
Regional Water) secured grant funds from the Iowa
Watershed Improvement Review Board and a loan
from USDA Rural Development to install and operate a
community sand filter system to treat wastewater from
all of Viking Village, a neighborhood that previously had
numerous individual failing onsite wastewater systems.
Finally, to complete shoreline and in-lake improvements,
DNR stabilized 7,927 feet of shoreline with rip rap,
drained the lake to eliminate nuisance fish species (yel-
low bass), repaired the dam gate and installed new fish
reefs, jetties and spawning beds to improve the fishery
and angler access. The project also included completion
of a 5.5-mile hiking trail around the park, using the tops
of the dams of the newly constructed grade stabilization
structures to provide hiking access to portions of the
park previously blocked by eroding gullies.
Results
Viking Lake Chlorophyll a TSI Levels: 2004-2014
67
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2004 2006 2008 2010 2012
Clean Water Act 305b Reporting Cycle Year
2014
Figure 3. Data showed that Viking Lake attained TSI standards
beginning in 2012.
year (51 percent). Post-project water quality monitor-
ing showed various improvements, including improved
Secchi depth (water clarity), reduced turbidity, reduced
phosphorus and reduced chlorophyll a levels (Figure 2).
In addition, algae blooms have declined, allowing ben-
eficial rooted aquatic vegetation to flourish in the clearer
water. Stocked fish species, including largemouth bass,
bluegill, crappie and channel catfish, are now growing
well and populations are healthy and balanced. The
improvements to water quality have helped make Viking
Lake once again a popular destination for anglers seek-
ing to catch quality fish.
On the basis of reduced chlorophyll a levels (TSI of
60 in 2014) and Secchi depths below the impairment
threshold (Figure 3), DNR removed Viking Lake's algae
impairment from Iowa's 2014 impaired waters list. The
lake remains listed as impaired for bacteria. Viking Lake
is therefore considered partially restored.
Partners and Funding
The restoration projects reduced sediment delivery to
the lake by an estimated 2,373 tons per year (51 percent)
and phosphorus by an estimated 3,086 pounds per
Project partners included the Montgomery SWCD, Iowa
DNR (Parks, Fisheries, Engineering and Watershed
Improvement sections), IDALS Division of Soil
Conservation, NRCS, Montgomery CCB, Page 1 Rural
Water District, Iowa DOT and private landowners.
Project funding from all sources totaled $1,078,513.
This total included funding from EPA CWA section 319
($224,469), DNR Lake Restoration Program ($312,880),
Iowa Publicly Owned Lakes Program ($69,714), federal
Sports Fish Restoration Fund ($42,471), Iowa Fish and
Wildlife Trust Fund ($41,412), Iowa Watershed Protection
Fund ($39,747), Iowa Watershed Improvement Review
Board ($58,500), USDA Rural Development ($49,500),
Iowa DOT ($1,779), USDA PL-566 ($37,631), USDA
NRCS ($88,160), and private landowners ($82,250).
yss
Ill
o
U.S. Environmental Protection Agency
Office of Water
Washington, DC
EPA841-F-15-001NN
September 2015
For additional information contact:
Daniel Case, Project Coordinator
Iowa Department of Agriculture and Land Stewardship
Daniel.Case@ia.nacdnet.net • 712-623-9680
Rachel Glaza, Project Officer
Iowa Department of Natural Resources
Rachel.Glaza@iowadnr.gov • 515-725-8388
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