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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