NONPOINT SOIREE SICCESS STOIY
Stakeholders Collaborate to Reduce Sediment and Restore Aquatic
Habitat in Rapid Creek
Waterbody Improved
Livestock grazing contributed excess sediment to Rapid Creek in
southeastern Idaho. Biological assessments showed that Lower
Rapid Creek failed to support cold-water aquatic life. As a result, Rapid Creek was added to Idaho's
1994 Clean Water Act (CWA) section 303(d) list for sediment impairment. Landowners and state and
local partners implemented agricultural best management practices (BMPs), and sediment levels
declined. Data collected in early 2012 showed improved biological scores, prompting the Idaho
Department of Environmental Quality (IDEQ) to remove Lower Rapid Creek from the state's 2012 list
of impaired waters.
Problem
Rapid Creek is in southeastern Idaho (Figure 1),
where rangeland is the predominant land use.
Livestock grazing, streambank erosion, sheet and rill
erosion, and erosion from roads contributed excess
sediment that negatively affected water quality.
The U.S. Environmental Protection Agency (EPA)
added Lower Rapid Creek to the CWA section 303(d)
list in 1994 based on IDEQ's section 305(b) water
quality assessment report.
In 1995 IDEQ completed a Beneficial Use
Reconnaissance Program (BURP) wadeable streams
rapid bioassessment on Lower Rapid Creek to
confirm the impairment. The BURP assesses the
health of streams using multimetric indices (biologi-
cal, physical and chemical) on a 0.0 (lowest) to 3.0
(highest) scale. The site received a stream macro-
invertebrate index (SMI) score of 0.0, a stream fish
index (SFI) score of 2.0 and a stream habitat index
(SHI) score of 3.0. Because the SMI score was 0.0,
which is below the minimum threshold levels, the
site automatically failed and was considered not to
be supporting its beneficial uses. As a result, Lower
Rapid Creek remained on the CWA section 303(d) list
for sediment impairment. (Note: The waterbody was
originally listed as Water Quality Limited Segment
#2334; in 2002 the segment was adjusted and
became assessment unit ID17040208SK023 _ 03.)
In 1999 IDEQ developed a sediment total maximum
daily load (TMDL) for the Portneuf River Subbasin,
which includes Rapid Creek; EPA approved the TMDL
in 2001.
Lower Portneuf River Subwatershed
Legend
,• Realtime USGS Stream Gages
if Continuous Monitoring Stations
v Municipal Wastewater Discharger
• Cities
— TMDLWaterbodles
Perennial Waterbodles
_J Reservation Boundaries
O Lower Portneuf 5th Field HUC
10 Kilometers
Figure 1. Rapid Creek is in southeastern Idaho's Lower
Portneuf River subwatershed.
Project Highlights
From 1989 to 1999, the Portneuf Soil and Water
Conservation District (SWCD) implemented a State
Agricultural Water Quality Program (SAWQP) grant-
funded project for the 16,195-acre Upper Rapid Creek
watershed. With help from SAWQP, landowners
implemented BMPs on approximately 3,839 critical
upland acres to reduce soil erosion.
From 2001 to 2007, the Portneuf SWCD led the
Upper Rapid Creek 319 project, helping landowners
implement BMPs on 2.8 miles of impaired stream
segments. This project built upon the 1989-1999
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Table 1. BURP data for Lower Rapid Creek, 1995-2012
Figure 2. A site in the Upper Rapid Creek watershed, before
(left, 2001) and after (right, 2007) BMPs were installed to
protect the stream corridor and reduce erosion.
SAWQP project. During the initial inventory pro-
cess, the SWCD designated 4,800 acres of the
watershed as critical. Landowners implemented
agricultural BMPs on 1,085 of these critical acres
using CWA section 319 funding; on 1,251 acres using
Conservation Reserve Program (CRP) funding; and
on 506 acres using Environmental Quality Incentives
Program (EQIP) funding. Watershed partners also
used a Conservation Innovation Grant (CIG) to assist
in completing a section 319 project. Using the four
integrated funding sources, landowners treated
59 percent of the critical acres with BMPs such as
off-stream alternative water sources, critical area
plantings, stream crossings, livestock use exclusion,
installation of water and sediment basins, and chan-
nel vegetation (Figure 2).
Results
Water quality has improved. The Idaho Association
of Soil Conservation Districts (IASCD) conducted
monitoring on the West Fork and the North Fork of
Rapid Creek in 2006-2007. On each stream, sites
were selected above and below the CWA section
319 project area to allow for upstream-downstream
comparisons of water quality before and after
BMP implementation. These data showed that the
suspended solids load declined by an estimated
26 pounds per day (8 percent) and that Escherichia
co/i and nitrogen concentrations also declined.
IDEQ collected water samples at the mouth of Rapid
Creek under high-flow conditions in 2007. These
averaged 23.6 milligrams per liter (mg/L) total sus-
pended solids (TSS), meeting the 80 mg/L high-flow
sediment (in TSS) TMDL target. IDEQ conducted
BURP bioassessments on Lower Rapid Creek in 2001,
2004 and 2012 (Table 1). After 2001 the creek met the
minimum average BURP score of 2.0, which indicates
full support of cold-water aquatic life; however, the
Year
2012
2004
2001
2001
BURP Monitoring
Site ID
2012SPOCA011
2004SPOCF001
2001SPOCA022
2001SPOCA020
1995M995SPOCA014
Stream
Macroinvertebrate
Index (SMI) Score
3
-
3
3
0
Stream Fish
Index (SFI)
Score
3
3
-
-
2
Stream Habitat
Index (SHI)
Score
2
1
3
2
3
Average
Scorea
2.67
2.00
3.00
2.50
0.00
a An average score below 2.00, as noted in bold, is considered not
supportive of cold-water aquatic life.
2012 bioassessment was the first to examine all three
multimetric indices (i.e., SMI, SFI and SHI) since 1995.
In 2012 the site received an overall average score of
2.67, which is considered fully supporting. In addi-
tion, IDEQ's 2012 percent fines data showed that
7.83 percent of the substrate consisted of material
less than or equal to 2.5 millimeters in size, signifi-
cantly less than the 30 percent threshold identified as
indicative of impairment by IDEQ's Guide to Selection
of Sediment Targets for Use in Idaho TMDLs. Because
data indicate good water quality, IDEQ removed the
5.62-mile-long Lower Rapid Creek assessment unit
(ID17040208SK023 _ 03) from the state's 2012 list of
impaired waters (for sediment impairment).
Partners and Funding
The Portneuf SWCD administered the CWA sec-
tion 319 project. Many stakeholders provided
support and technical assistance, including the
IASCD, IDEQ, Idaho Soil and Water Conservation
Commission, Idaho State Department of Agriculture,
U.S. Department of Agriculture's Natural Resources
Conservation Service, and private landowners.
Funding for the 2001-2007 CWA section 319 project
included $132,919 to support BMP implementa-
tion, $10,000 for grant administration and supplies,
$107,834 in landowner matching funds and $55,000
in IDEQ technical support matching funds. A CIG
grant provided additional matching funds for the
319 grant. A SAWQP grant provided $306,404 in
state funds for BMP implementation between 1989
and 1999. Additional funding sources supported
restoration efforts between 1985 and 2002 in both
the Upper Rapid Creek watershed ($756,462 in CRP
funds, with $45,570 landowner match; and $1,826
in EQIP funds, with $1,273 landowner match) and
the Lower Rapid Creek watershed ($363,042 in CRP
funds, with $21,870 landowner match).
yss
Ill
o
U.S. Environmental Protection Agency
Office of Water
Washington, DC
EPA841-F-16-001A
January 2016
For additional information contact:
Lynn Van Every
Idaho Department of Environmental Quality
Pocatello Regional Office
208-236-6160 • Lynn.Vanevery@deq.idaho.gov
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