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Section 319
NONPOINT SOURCE PROGRAM SUCCESS STORY
Missouri
Watershed Planning and On-the-Ground Implementation Improve Water
Quality in Dardenne Creek
Waterbody Improved
Studies conducted by the Missouri Department of Natural Resources
(MDNR) between 1998 and 2002 showed poor aquatic habitat and
elevated levels of sediment deposition in Dardenne Creek. Based on the study results, in 2002 the
U.S. Environmental Protection Agency placed the creek on the Clean Water Act (CWA) section 303(d)
list of impaired waters for failure to meet water quality standards for the aquatic life designated use
because of unknown pollutants. A broad coalition of landowners and other stakeholders addressed
runoff and erosion through both education and implementation of best management practices
(BMPs). Recent data show declines in inorganic sediment levels and improvements in aquatic habitat,
prompting MDNR to remove a six-mile-long segment of Dardenne Creek from the 2010 CWA section
303(d) list for sediment impairment.
Problem
Dardenne Creek drains a 165-square-mile water-
shed in St. Charles County, Missouri, and flows
northeast to the Mississippi River (Figure 1). Land
use in the watershed consists of some agriculture
mixed with rapidly developing suburban outgrowth
from St. Louis. The creek is a popular site for water-
based recreation activities (Figure 2; see page 2).
Studies conducted by MDNR in 1998, 2000 and
2002 indicated poor water quality and poor aquatic
habitat conditions in much of Dardenne Creek.
In 2000 MDNR conducted macroinvertebrate
sampling at five monitoring sites along the creek.
The health of the biotic community was assessed
on the basis of four primary biological metrics,
which were compared to the state's numeric
biological criteria for reference streams within the
same ecological region as Dardenne Creek. The
results indicated that four of the five sites achieved
the status of partially biologically sustaining or
non-biologically sustaining. Based on these data,
in 2002 the U.S. Environmental Protection Agency
determined that Dardenne Creek did not meet its
aquatic life designated use and added the creek
to the state's list of impaired waters for unknown
pollutants from urban/rural nonpoint sources.
A 2000 study by the Greenway Network, Inc.
(a regionally based grassroots, volunteer-based
natural resources organization) and the Center
for Agricultural, Resource and Environmental
Systems (CARES) estimated that 62,509 tons of
soil was eroding into Dardenne Creek annually.
\ Dardenne
Creek
Watershed
Figure 1. Dardenne
Creek Watershed
lies near the eastern
border of Missouri.
Subsequently (in 2002), MDNR conducted sediment
studies at six sites along the creek. Across the study
sites, the average percent fine sediment deposition
(proportion of particles less than 2 millimeters in
size) was 64.86 percent, 25 percent greater than
the percent fine sediment deposition for control
streams. While the state does not have a sediment
deposition water quality standard, Missouri's 303(d)
listing methodology document's (LMD) target
value for median percent fine sediment deposi-
tion is no more than 20 percent greater than the
median sediment deposition for control streams.
As a result, MDNR added inorganic sediment as
an additional pollutant to Dardenne Creek on the
2004/2006 CWA section 303(d) list. Much of this
erosion was attributed to hydrologic alterations
caused by channel modification and watershed
urbanization.

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Project Highlights
Projects to actively address sediment problems in
the Dardenne Creek watershed have been under
way since at least 1997. In 1997 the Dardenne Creek
Watershed Alliance (the Alliance), composed of local
citizens and representatives from 15 organizations,
began developing the Dardenne Creek Wetlands and
Watershed Protection and Restoration Plan. MDNR,
CARES and the Greenway Network also provided
support. Partners gathered public input, collected
water quality data and used a geographic informa-
tion system to develop a watershed decision support
system. The plan, completed in 2000, outlined
recommendations for protection and restoration on
a watershed scale. Objectives of the plan included
(1) improving public knowledge of water quality
issues and protection; (2) reducing soil erosion on
agricultural lands; (3) reducing stormwater runoff
and urban erosion; (4) promoting comprehensive
land use and watershed planning; and (5) promoting
wetland protection, enhancement, management and
mitigation. The plan continues to guide the efforts of
the Alliance, the Greenway Network, city and county
governments, and the St. Charles Soil and Water
Conservation District (SWCD).
Since 2003, SWCDs in the watershed have imple-
mented 21 agricultural BMPs, including tillage
management, terraces, sod waterways and a reser-
voir to help stabilize stream erosion. The practices
have prevented an estimated 2,786 tons of soil from
entering Dardenne Creek.
St. Charles County used its Unified Development
Ordinance to develop and modify ordinances that
promote the protection of natural watercourses and
riparian buffers, tree preservation, BMP inspec-
tion and wastewater disposal regulations. The
county also stabilized stream banks and improved
stormwater/sewer infrastructure. The cities of
St. Charles and St. Peters implemented stormwater
control projects such as construction and post-
construction sediment control through Phase II
municipal separate storm sewer system (MS4)
permits.
The City of St. Peters and the SWCD, in coordina-
tion with the Alliance, supported the installation
of two U.S. Geological Survey gauging stations in
Dardenne Creek. The Alliance also led educational
workshops for students, organized an annua!
"Dardenne Day" to educate the public about
water quality, developed a website, and helped to
organize a volunteer monitoring Stream Team.
Figure 2. Eastern Missouri's Dardenne Creek is a
popular site for water-based recreation activities.
Results
Sediment deposition in Dardenne Creek declined as
a result of practices implemented throughout the
watershed. A 2008 MDNR study found that median
fine sediment deposition in the creek decreased
from 25 percent above the median sediment deposi-
tion in a control stream in 2002 to 12.5 percent above
the median sediment deposition (which meets the
state's 303(d) LMD sediment target value). As a
result, MDNR removed a six-miie-long segment of
Dardenne Creek from the state's CWA section 303(d)
list in 2010 for inorganic sediment impairment
Partners and Funding
The Alliance developed the Wetland and Watershed
Protection and Restoration Plan with $112,470 from
a CWA section 104 grant. CWA section 319 grant
funding supported implementation of portions
of the plan, including $9,862 for the Alliance to
conduct education and outreach and $41,980 for
the St. Charles SWCD to implement three nonpoint
source projects in the Dardenne Creek watershed.
SWCDs used $21,390 in state cost-share funds
to implement 21 agricultural BMPs. Landowners
participating in cost-share provided 25 percent
or more of the project costs, totaling more than
$5,348. St. Charles County received $106,561 in
State Revolving Fund grants to stabilize stream
banks and improve stormwater and sewer infra-
structure. State Revolving Fund grants also funded
stormwater projects conducted by the cities of
St. Charles ($51,021) and St. Peters ($43,460).
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U.S. Environmental Protection Agency
Office of Water
Washington, DC
EPA 841-F-12-001A
January 2012
For additional information contact:
Greg Anderson
Missouri Department of Natural Resources
Water Protection Program
573-751-7144 • greg.anderson@dnr.mo.gov

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