Section 319
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NPNP3INT SOIJRSE PIPJUAM Sl'EEESS
Implementing Best Management Practices and Targeting Technical
Assistance Restores Lake
\A/ t h H I H Agricultural activities contributed excess nutrients and sediment to
Wai DOy I 3Ve< North Dakota's Lake LaMoure, resulting in a hypereutrophic (high
nutrient concentrations and poor water clarity) state. As a result, North Dakota added the lake to its
2002 Clean Water Act (CWA) section 303(d) list of impaired waters as threatened for its recreation and
aquatic life designated uses. Implementing agricultural best management practices (BMPs) reduced
the amount of nonpoint source pollution entering the lake. As a result, lake clarity has increased and
chlorophyll a levels have decreased, allowing Lake LaMoure to return to a mesotrophic (lower nutrient
concentrations and greater water clarity) state. On the basis of those data, North Dakota removed Lake
LaMoure from the CWA section 303(d) list in 2010.
Problem
Lake LaMoure is a 409-acre reservoir on
Cottonwood Creek in southeastern North Dakota.
The lake provides recreational opportunities
such as swimming, boating and fishing (Figure 1).
Agriculture (crop and livestock production) is the pri-
mary land use in the lake's 160,000-acre watershed.
In the 1990s, local residents became concerned as
frequent algae blooms plagued the lake in mid- to
late-summer, and the fish community became
increasingly dominated by less desirable fish such
as carp and bullheads. In response, in 1995 the
LaMoure County Soil Conservation District (SCO)
began evaluating the relationship between land
management and degrading water quality in the
Lake LaMoure/Cottonwood Creek watershed. The
SCO measured water quality and quantity and
inventoried the land use practices in the watershed.
The 1995 assessment revealed that Lake LaMoure
received approximately 72,712 pounds (Ibs) of nitro-
gen and 11,987 Ibs of phosphorus—roughly equal
to a fertilization rate of 147 Ibs/acre nitrogen and
24 Ibs/acre phosphorus. Models also indicated that
the lake generated an additional internal loading
amount equal to a fertilization rate of 13.8 Ibs/acre
nitrogen and 11.4 Ibs/acre phosphorus.
The SCO's assessment identified that recreational
use impairments in Lake LaMoure were primarily
caused by nonpoint source pollutants from agri-
cultural lands, including nutrients (nitrogen and
phosphorus) and suspended sediments. Potential
nonpoint pollutant sources included excessively
tilled croplands, overgrazed rangeland and livestock
winter feeding areas. The assessment also identified
Figure 1. Lake LaMoure is in southeast North Dakota.
the lake's carp population as possibly contributing
to resuspension of sediments and nutrients through
rooting and foraging activities on the lake bottom.
The SCO's assessment determined that in-lake
phosphorus concentrations needed to be reduced to
a mean annual concentration of 0.19 milligrams per
liter (mg/L) to change the lake's trophic state from
hypereutrophic to mesotrophic. Trophic State Index
(TSI) values are calculated according to seasonal
means of total phosphorus, chlorophyll a (the pho-
tosynthetic pigment that causes the green color in
algae and plants), and Secchi disc transparency (indi-
cating water clarity). TSI values are often grouped
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into trophic state classifications: oligotrophy, or low
productivity (values of 0-40); mesotrophy, or moder-
ate productivity (values of 40-50); and eutrophy, or
high productivity (values of 50 or more). TSI values
can assess changes in a lake's productivity over time
and compare the productivity of lakes in the same
region.
Project Highlights
The SCO developed a watershed project implemen-
tation plan that identified beneficial use improve-
ment and nonpoint source pollutant-reduction goals,
specific activities for accomplishing the goals and
a method for evaluating progress. The SCO began
targeting conservation planning assistance along
with voluntary implementation of BMPs in 1997.
With help from the SCO and other federal, state and
local partners, landowners applied BMPs to 56,950
acres, including implementing conservation tillage
(22,010 acres) and no-till (1,816 acres), converting
cropland to hayland (1,149 acres), establishing ripar-
ian easements (41 acres), stabilizing streambanks
(1,915 linear feet), and installing exclusion fencing
(2,610 linear feet). In addition, landowners adopted
prescribed grazing management on 319 acres, strat-
egies for better managing livestock waste nutrients
(on 17,472 acres), and improved crop residue man-
agement (on 2,246 acres). The SCO worked with
landowners to implement 10 manure management
systems and install fencing to exclude livestock
from riparian areas. After the watershed project
had ended, one additional system was installed
with funding from Natural Resources Conservation
Service's Environmental Quality Incentive Program.
Results
Implementing BMPs reduced water pollution and
improved the lake's water quality. Analysis of
chlorophyll a data and Secchi disk transparency
yields TSI scores that show that Lake LaMoure
has improved from a hypereutrophic to a meso-
trophic state (Figure 2). When analyzed for trends
using a Seasonal Kendall Test, the chlorophyll a
data showed a significant decline (slope of -0.810,
p < 0.1). The Secchi disk transparency readings
showed a significant increase (slope of 0.124,
p < 0.05). Water quality improved, and recre-
ation and aquatic life designated uses have been
restored. On the basis of those data, North Dakota
removed Lake LaMoure from the state's CWA sec-
tion 303(d) list of impaired waters in 2010.
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03/07/94 08/03/96
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Figure 2. TSI scores for Lake LaMoure from 1994 through 2008.
Partners and Funding
The LaMoure County SCO led the watershed
assessment and development of the Lake LaMoure/
Cottonwood Creek Watershed Project. The SCO
hired staff to work with watershed landowners to
develop contracts and deliver technical assistance
for implementing BMPs. SCO project staff worked
closely with federal, state and local partners, includ-
ing the North Dakota Wetlands Trust (renamed
the Natural Resources Trust), Natural Resources
Conservation Service, U.S. Fish and Wildlife
Service, U.S. Environmental Protection Agency,
and the Nonpoint Source BMP Team—a CWA
section 319-funded engineering program through
the Sheyenne James Resource Conservation and
Development program.
In addition, the North Dakota Department of Health
provided oversight for project management, devel-
oped the quality assurance project plan, conducted
training for proper water quality sample collection,
and helped to develop and implement outreach
and education activities. The North Dakota Game
and Fish Department provided financial assistance
for establishing riparian easements and restoration
practices. Partners have encouraged and main-
tained public involvement by holding workshops,
distributing newsletters and offering presentations
to community groups.
The project received $1,753,668 in CWA section
319 funding that was matched by $1,169,112 in local
funds (cash and in-kind services) from landowners.
I
o
U.S. Environmental Protection Agency
Office of Water
Washington, DC
EPA841-F-11-001J
February 2011
For additional information contact:
Bob Flath, LaMoure County Soil Conservation District
701-883-5344 • Robert.Flath@nd.nacdnet.net
Greg Sandness, North Dakota Department of Health
701-328-5232 • gsandnes@nd.gov
Eric Steinhaus, U.S. Environmental Protection Agency Region !
303-312-6837 • steinhaus.eric@epa.gov
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