Section 319
NDNPDINT SBIHE* PROGRAM SUCCESS STDRY
Best Management Practices Result in Turbidity Delistings in Two Streams
\A/ t h H I H
Wa rOOdy I IprOVeO
Excess turbidity due in part to practices associated with cattle and crop
productionimpaired Dirty Creek and one of its tributaries, Elk Creek. As
a result, Oklahoma added both streams to the state's 2006 Clean Water Act (CWA) section 303(d) list of
impaired waters for turbidity. Implementing best management practices (BMPs) helped reduce erosion
from grazing lands and croplands, and turbidity levels decreased. As a result, Dirty and Elk creeks have
been nominated for removal from the state's CWA section 303(d) list for turbidity in 2010.
Problem
Elk Creek is in Mclntosh County in the central
eastern part of Oklahoma. It is a tributary of Dirty
Creek, located in Muskogee and Mclntosh counties
(Figure 1). Land use in the watershed is primarily
cattle and poultry production in addition to cropland
(mainly wheat and corn). Sediment from eroding
grazing lands and croplands contributed to elevated
turbidity in both Elk and Dirty creeks.
Monitoring showed that seasonal base flow water
samples exceeded 50 nephelometric turbidity units
(NTU) in 2006 by 17 percent in Elk Creek and by
31 percent in Dirty Creek. A stream is considered
impaired by turbidity if 10 percent or more of the
seasonal base flow water samples exceed 50 NTUs
(based on no more than five years of data prior to the
assessment year). The high turbidity levels prompted
Oklahoma to add the 44-mile-long Dirty Creek and
the 14-mile-long Elk Creek to the 2006 CWA section
303(d) list of impaired waters as not attaining the fish
and wildlife propagation designated use.
Dirty Creek
Elk Creek
Dirty Creek Watershed
Figure 1. Elk Creek is a tributary within the Dirty
Creek watershed.
Project Highlights
Landowners implemented numerous BMPs with
support from Oklahoma's locally led cost-share
program and Natural Resources Conservation
Service (NRCS) programs such as the Environmental
Quality Incentives Program (EQIP), Grazing Land
Conservation Program (GLC), and general technical
assistance programs. From 2004 to 2007, landown-
ers implemented prescribed (managed) grazing on
6,605 acres, which included installing 59,653 linear
feet of cross-fencing, constructing 106 ponds, and
providing 7 alternative water supply tanks. To further
improve grazing land quality and reduce erosion,
cooperators managed brush on 141 acres, removed
invasive weeds from 3,690 acres, and planted
supplemental forage on 3,042 acres.
Elk Creek
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— 100-
1—
X
•a
5 50-
,2
0-
Dirty Creek Turbidity Levels
31% 0%
exceedance exceedance
•
•
. . •
f. > :
n •
2006 2010
Assessment Year
Elk Creek Turbidity Levels
200-
3
£ 150.
X
2 100.
£
t-
50.
0.
17% 8%
exceedance exceedance
.
* *
*..••*" •"!•/"
2006 2010
Assessment Year
Figures 2 and 3. Less than 10 percent of samples in Dirty and Elk creeks exceeded the turbidity standard.
Landowners also adopted several cropland BMPs,
including converting 480 acres of land from conven-
tional to conservation tillage (mulch-till or no-till),
implementing conservation/cover crop rotation on
447 acres, constructing one grade stabilization struc-
ture, and building 5,000 feet of terraces. Nutrient
management plans were written for 3,270 acres,
and one waste storage facility and two composting
facilities were constructed. Landowners managed
55 acres for wetland wildlife habitat and 1,228 acres
for upland wildlife habitat.
Landowners implemented additional BMPs from
2008 through 2010 that expanded the initial grazing
and cropland improvements. Recent BMPs included
an additional 10,240 acres of prescribed grazing,
with 75,353 linear feet of cross-fencing, 25 additional
ponds, and 6 alternative water supply tanks. Another
1,149 acres were managed for brush, 395 acres
received supplemental forage/hay planting, and
4,102 acres had weed management. Cooperators
converted 283 acres of conventional tillage cropland
to mulch tillage, and conservation crop rotations
were implemented on 55 acres. Nutrient manage-
ment occurred on 3,824 acres, and three waste
storage facilities were constructed. Finally, 919 acres
were managed for upland wildlife habitat and
183 acres of forest were improved.
Results
Monitoring and data analysis was performed by the
Oklahoma Conservation Commission (OCC) as part
of the state's Rotating Basin Monitoring Program
(RBMP). As a result of the implemented practices,
turbidity has decreased in both the Dirty Creek and
Elk Creek watersheds (Figures 2 and 3). In the 2006
and 2008 assessments, 17 percent of Elk Creek
seasonal base flow water samples exceeded the tur-
bidity criterion of 50 NTU, while 31 percent of Dirty
Creek samples exceeded. In the 2010 assessment,
none of the Dirty Creek base flow values exceeded
the criterion, and only 8 percent of the Elk Creek val-
ues exceeded the criterion. Both Elk and Dirty creeks
have been nominated for removal from Oklahoma's
CWA section 303(d) list for turbidity impairment in
2010. Both creeks are now in partial attainment of
the fish and wildlife propagation designated use.
Partners and Funding
The improvement in water quality in Dirty and Elk
creeks was documented by the OCC's statewide
nonpoint source ambient monitoring program. The
RBMP, which now includes a probabilistic compo-
nent, is funded through the EPA CWA section 319
program at an average annual cost of $1 million.
Monitoring costs include personnel, supplies, and
lab analysis for 19 parameters from samples col-
lected every five weeks at about 100 sites for a
total of 20 episodes per five year cycle. In-stream
habitat, fish, and macroinvertebrate samples are
also collected. Statewide educational efforts
through Blue Thumb are also funded by EPA CWA
section 319 at a cost of approximately $600,000
annually. These costs include supplies for monthly
monitoring of 100 sites, as well as trainings and
other outreach activities. The Oklahoma cost-share
program provided $69,059 in state funding for BMPs
in this watershed through the Muskogee County
and Checotah County Conservation Districts, and
landowners contributed nearly $85,352 through this
program. The NRCS spent approximately $377,930
for implementation of BMPs in the area from 2003 to
2007 and has obligated just over $312,623 for BMPs
from 2008 through 2010.
U.S. Environmental Protection Agency
Office of Water
Washington, DC
EPA841-F-11-001T
March 2011
For additional information contact:
Shanon Phillips, Director
Water Quality Division
Oklahoma Conservation Commission
shanon.phillips@conservation.ok.gov
405-522-4500
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