Section 319
NONPOINT
RDGR2M SUCCESS STORY
Land Treatment and Education Efforts Result in Lower Atrazine
Concentrations
Watprhnrlv Imnrnx/pH High concentrations of atrazine measured in the primary
vv" J''v y ll!lrjl"'v-u inflow to Recharge Lake caused the Nebraska Department
of Environmental Quality (NEDEQ) to list the reservoir on the state's 1994 Clean Water Act
(CWA) section 303(d) list of impaired waters. The Upper Big Blue Natural Resources District
(UBBNRD) initiated a project to provide farmers with technical assistance on herbicide
application and help them to implement a series of agricultural best management practices
(BMPs). Those changes resulted in significantly reduced concentrations of atrazine,
prompting NEDEQ to remove the atrazine impairment for Recharge Lake from the 2010
CWA section 303(d) list.
Problem
Recharge Lake is a 55-acre reservoir in Nebraska's
Big Blue River Basin (Figure 1). The lake was con-
structed in 1990 as part of a five-year groundwater
recharge study in Nebraska's Bruce L. Anderson
Recreation Area. The lake now provides water-
based recreational opportunities.
Recharge Lake's 8,200-acre watershed supports
mainly corn, grain sorghum, and soybean fields.
Farmers use herbicides containing atrazine as the
primary form of chemical control for weeds in corn
and grain sorghum. An extensive amount of infor-
mation and data was collected from two parallel
studies coordinated by the University of Nebraska
Cooperative Extension in the early 1990s. Part of
the gathered information indicates that 100 per-
cent of the corn and grain sorghum acres received
applications of atrazine—or atrazine in combination
with another herbicide. The studies show that farm-
ers applied approximately 8,813 pounds of active
ingredient to crops in the watershed in 1992.
In the spring of 1992, high concentrations of
atrazine were measured in the primary inflow to
Recharge Lake. Follow-up monitoring conducted
in the reservoir during 1992 documented atrazine
concentrations as high as 93 micrograms per liter
(jUg/L)—well above Nebraska's chronic atrazine
standard of 1.0/jg/L in effect at the time. The
Figure 1. Nebraska's Recharge Lake supports recreational
uses.
chronic atrazine standard changed to 12.0/jg/L in
2000. On the basis of those data, Nebraska added
Recharge Lake to its 1994 CWA section 303(d) list
for impairment to the aquatic life designated use
because of atrazine levels. Recharge Lake remained
on the impaired list for atrazine during the 1996,
1998, 2006 and 2008 assessment cycles. In 2006
NEDEQ added nutrients to the list of impairments,
which carried over to the proposed 2010 CWA sec-
tion 303(d) list. NEDEQ will also list Recharge Lake
for mercury in fish tissue on the 2010 303(d) list.
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Project Highlights
In 1994 UBBNRD initiated a CWA section 319
project in the Recharge Lake watershed to work
with farmers to address atrazine concerns. The
U.S. Department of Agriculture (USDA) Natural
Resources Conservation Service identified 393
acres of highly erodible cropland that it consid-
ered to be the most critical areas for contributing
excessive atrazine. By March of 1995, farmers had
enrolled 257 acres of the critical area in USDA pro-
grams. Farmers also enrolled another 4,204 acres
outside the critical area in USDA programs.
Agriculture BMPs implemented in those areas
include nutrient and pesticide management, proper
management of animal waste, conservation cover
crops and rotation, and efficient management of
irrigation water. As part of the assistance provided
through the CWA section 319 grant, agricultural
technical staff worked one-on-one with all farm
operators in the watershed to provide informa-
tion and recommend practices that would reduce
surface runoff of pesticides and other pollutants.
Results
Follow-up monitoring indicates that the amount
of atrazine applied in the watershed decreased to
4,780 pounds, a reduction of 45 percent. From 1995
through 2009, only 4 of 42 samples (10 percent)
collected exceeded the chronic criteria (12.0/jg/L).
In 2009 none of the 22 samples exceeded the
criteria (Figure 2). The maximum concentration
detected was 1.15jug/L As a result, NEDEQ
removed Recharge Lake's atrazine impairment from
the state's 2010 CWA section 303(d) list. While
atrazine's use has decreased in many Nebraska
watersheds since the early 1990s, the adoption
of land management practices and the delivery of
educational programs have further reduced concen-
trations of atrazine in runoff.
Recharge Lake Atrazine Concentrations
70.
60'
Q.
a
T u
1992 1993 1994 1995 1995 1997 2002
2009
Figure 2. Atrazine concentrations fell over time. Boxplots
indicate the interquartile range (25th-75th percentile), median
and outliers of the date in each of the two periods. Pre-project
data consist of years 1992 through 1993, while post-project data
range from 1994 through 2009.
Partners and Funding
Several partners were involved in the overall
project. The UBBNRD sponsored the project,
contributing $78,456 along with $46,666 in CWA
section 319 funding for technical assistance to
operators and water quality monitoring. The USDA
provided $124,774 for technical assistance and cost
share/incentives to operators wanting to adopt land
management practices. The University of Nebraska
Cooperative Extension conducted pre-and post-
project landowner/operator surveys. Ciba-Geigy
also provided funding support.
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U.S. Environmental Protection Agency
Office of Water
Washington, DC
EPAEPA841-F-10-001K
May 2010
For additional information contact:
Paul Brakhage
Nebraska Department of Environmental Quality
402-471-4224 • paul.brakhage@ndeq.state.ne.us
Rodney DeBuhr
Upper Big Blue Natural Resources District
402-362-6601 • rdebuhr@upperbigblue.org
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