Section 319
NONPOINT SOORGE PROGRAM SOGGESS STORY
Implementing Agricultural Best Management Practices Decreases
Turbidity in Wildhorse Creek
Waterbody Improved Hig'turbidity' dL;e 'n.part to.Practices associatedth catt,e
production, resulted in impairment of Wildhorse Creek and
placement on Oklahoma's Clean Water Act (CWA) section 303(d) list of impaired waters
in 2008. Implementation of best management practices (BMPs) to promote better quality
grazing land and cropland decreased sediment loading into the creek. As a result, an
11-mile-long segment of Wildhorse Creek was removed from Oklahoma's 2012 CWA
section 303(d) list for turbidity impairment. This segment of Wildhorse Creek is now in full
attainment of its fish and wildlife propagation (FWP) designated use.
Problem
Wildhorse Creek is located in Stephens County
in southwestern Oklahoma (Figure 1). Land use in
the 22,870-acre watershed is primarily pasture for
cattle production, with some wheat cropland. Poor
grazing land and cropland management contributed
to excess sedimentation in the creek. In the 2008
water quality assessment, monitoring showed that
23 percent of Wildhorse Creek's seasonal base flow
water samples exceeded 50 nephelometric turbid-
ity units (NTU). A stream is considered impaired by
turbidity if more than 10 percent of the seasonal
base flow water samples exceed 50 NTU (based
on 5 years of data before the assessment year). On
the basis of these assessment results, Oklahoma
added an 11-mile-long segment of Wildhorse
Creek (OK310810040140 _ 00) to the 2008 and
subsequent CWA section 303(d) lists for nonattain-
ment of the FWP designated use due to turbidity
impairment.
• Monitoring Site
• Wildhorse Creek Watershed
Project Highlights
Landowners implemented BMPs with assistance
from Oklahoma's locally led cost-share program and
through the local U.S. Department of Agriculture's
Natural Resources Conservation Service (NRCS)
Environmental Quality Incentives Program (EQIP),
general conservation technical assistance program,
and Conservation Stewardship Program (CSP).
From 2008 to 2011, landowners in the watershed
reduced the potential for erosion from grazing lands
by implementing prescribed grazing on 2,271 acres
and proper nutrient management on 2,434 acres
Figure 1. The Wildhorse Creek watershed is in southwestern
Oklahoma.
and by installing 14 diversions (diverting water flow
to less erosion-prone areas) and 29 grade stabiliza-
tion structures. Over 800 acres of range and pasture
received supplemental vegetative planting in
erosive areas, and 2,272 acres of pest (weed) man-
agement helped to improve the quality of grazing
lands. Installation of cross-fencing and alternative
water supplies optimized usage of grazing lands.
Conservation cover crop rotations and conservation
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tillage methods instituted on more than 3,000 acres
helped to address erosion from cropland.
Additional BMPs implemented in 2012 include
cross-fencing, 28 ponds, eight diversions, another
grade stabilization structure, forage/biomass plant-
ing in critical areas and pastures, and additional
nutrient management.
Results
The Oklahoma Conservation Commission's (OCC's)
Rotating Basin Monitoring Program, a statewide
nonpoint source ambient monitoring program,
documented improved water quality in Wildhorse
Creek due to landowner implementation of BMPs
(Figure 2). BMPs designed to improve pasture and
rangeland result in denser vegetation and fewer
bare spots, which equates to less potential runoff
of soil into waterbodies. In the 2008 assessment,
23 percent of seasonal base flow water samples
exceeded the turbidity criteria of 50 NTU. This
exceedance was reduced to zero percent in the
2012 assessment (Figure 3). Accordingly, Wildhorse
Creek has been removed from Oklahoma's 2012
CWA section 303(d) list for turbidity impairment
and is now in full attainment of the FWP desig-
nated use.
Partners and Funding
The Rotating Basin Monitoring Program is sup-
ported by U.S. Environmental Protection Agency
CWA section 319 funds at an average annual cost
of $1 million. Monitoring costs include personnel,
supplies, and lab analyses for 18 parameters from
samples collected every 5 weeks at about 100 sites.
In-stream habitat, fish, and macroinvertebrate sam-
ples are also collected. Approximately $600,000 in
CWA section 319 funding supports statewide edu-
cation, outreach, and monitoring efforts through the
OCC's Blue Thumb program. The Oklahoma cost-
share program provided $11,719 in state funding
for BMPs in this watershed through the Stephens
County Conservation District, and landowners
contributed $8,035 through this program. The NRCS
spent approximately $1,250,000 for implementa-
tion of BMPs in the watershed from 2008 to 2011
through NRCS EQIP, CSP, and general technical
Figure 2. Wildhorse Creek following the implementation
of best management practices.
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Wildhorse Creek
23% exceedance 0% exceedance
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2008 2012
Assessment Year
Figure 3. Monitoring data show that turbidity levels in
Wildhorse Creek have declined.
assistance funds. An additional $193,000 was spent
in 2012. Landowners provided a significant percent-
age toward BMP implementation in these programs
as well.
UJ
O
U.S. Environmental Protection Agency
Office of Water
Washington, DC
EPA841-F-14-001AA
April 2014
For additional information contact:
Shanon Phillips
Oklahoma Conservation Commission
405-522-4500 • shanon.phillips@conservation.ok.gov
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