Section 319
NONPOINT SOURCE PROGRAM SUCCESS STURY
Implementing Management Practices Decreases Bacteria in the Raft River
Waterbody Improved
Historical agriculture and grazing land uses contributed nonpoint
source pollution to Idaho's Raft River. As a result, in 1994 the
Idaho Department of Environmental Quality (DEQ) added the Raft River Subbasin to the state's Clean
Water Act (CWA) section 303(d) list of impaired waters for bacteria, sediment and other pollutants.
Stakeholders have implemented agricultural and grazing-related best management practices (BMPs)
throughout the subbasin, which has led to water quality improvements. One 19-mile-long segment
(assessment unit) in the watershed now meets water quality standards for bacteria, prompting DEQ
to propose removing the bacteria impairment for this assessment unit from the state's list of impaired
waters in the 2012 Integrated Report.
Problem
The Raft River originates in Box Elder County in
northern Utah and flows north to join the Snake
River in southeastern Idaho's Cassia County
(Figure 1). Most (approximately 82 percent) of the
967,150-acre Raft River Subbasin is in Idaho. The
major land uses in the subbasin are rangeland
(49 percent), forests (25 percent), and cropland and
pastureland (25 percent).
Intermittent water quality data collected from the
late 1980s to the mid-1990s indicated that the
Raft River failed to support its secondary contact
recreation beneficial use because of elevated
bacteria levels. The river also failed to support a
number of other beneficial uses. As a result, in
1994 the DEQ added a portion of the Raft River
Subbasin to the state's CWA section 303(d) list
of impaired waters, citing numerous pollutants,
including bacteria, sediment, dissolved oxygen,
temperature and salinity. In 2002, Idaho modified its
segmentation framework to conform to assessment
units (organized by stream order). The impaired
fourth-order (main stem) Raft River assessment
units are ID17040210SK013 _ 04 (Idaho/Utah
border to Edwards Creek), ID17040210SK010 _ 04
(Unnamed Tributary to Cottonwood Creek) and
ID17040210SK008 _ 04 (Cottonwood Creek to
Cassia Creek). Impaired tributaries to the Raft River
are listed as separate assessment units.
To confirm impairment and determine background
levels of bacteria (and other pollutants), DEQ and
the Idaho Association of Soil Conservation Districts
(IASCD ) collected water quality data along the
Raft River from 1999 through 2002. Idaho's sec-
ondary contact recreation water quality standard
Figure 1. Idaho's Raft River is in the Snake River
watershed.
states that if a single measurement exceeds
576 colony-forming units per 100 milliliters of water
(576 cfu/100 ml), the possibility exists that the
30-day geometric mean of 126 cfu/100 ml may
have been violated and additional sampling should
be conducted to determine the geometric mean.
Five samples collected within the 30-day period
of May 5-June 3, 2002 at the Raft River Narrows
monitoring site (near the uppermost extent of
assessment unit ID17040210SK010 _ 04) revealed a
geometric mean of 349 cfu/100 ml, a clear exceed-
ance of state water quality standards.
To help identify and address pollution problems,
DEQ developed Raft River Subbasin total maximum
daily loads (TMDLs) for bacteria, sediment and
temperature in 2004. TheTMDL identified potential
pollution sources of bacteria as confined animal
feeding operations, septic systems, and activities
such as farming and grazing.
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In 2006, staff members from the Idaho Soil and
Water Conservation Commission (SWC), IASCD and
the East Cassia Soil and Water Conservation District
(SWCD) worked together to develop the Raft River
TMDL Implementation Plan for Agriculture. The plan
outlined an adaptive management approach for
implementing BMPs to meet the requirements of
the Raft River TMDL.
Results
Project Highlights
As early as the 1990s, watershed partners were
working to reduce pollution in the Raft River. DEQ
used CWA section 319 funds to support a Raft
River Riparian and Watershed Demonstration
project in 1999-2001. Project partners worked with
property owners to stabilize streambanks, install
erosion control BMPs and revegetate barren areas.
Between 2004 and 2008, the U.S. Department
of Agriculture's Natural Resources Conservation
Service (NRCS), the Idaho SWC and the East Cassia
SWCD worked with landowners in the Raft River
Subbasin to implement numerous BMPs, includ-
ing livestock access controls (104,486 feet of
fencing across 3,598 acres), conservation cover
crops (18,574 acres), contour farming practices
(5,426 acres), 23 water and sediment control basins,
nutrient management plans (5,980 acres) and relo-
cation of corrals. Approximately 43,600 acres were
removed from production through NRCS'
Conservation Reserve Program. The Idaho SWC
provided technical and financial assistance to help
landowners convert from flood to sprinkler irriga-
tion. This conservation practice eliminated runoff
from irrigation return flows, a major factor in reduc-
ing bacterial sources impacting this portion of the
Raft River.
Federal agencies have also worked to reduce the
amount of nonpoint source pollution reaching the
Raft River. Since the mid-1990s, the Forest Service
has implemented grazing management require-
ments and installed watering troughs, riparian fenc-
ing and other livestock exclusion practices on its
leased allotments. Similarly, the U.S. Bureau of Land
Management (BLM) excluded livestock grazing on
BLM-administered land near the perennial segments
of the Raft River (Figure 2), planted cottonwood
trees within exclosures (small fenced areas installed
to prevent livestock and wildlife from accessing
riparian areas), and implemented riparian pasture
BMPs along Cassia Creek, a Raft River tributary.
BMP implementation
efforts are helping to
restore the Raft River.
Water quality samples col-
lected in the summers of
2010 and 2011 in the Raft
River assessment unit
ID17040210SK010_04
(Unnamed Tributary
to Cottonwood Creek)
showed that bacteria
levels are now meet-
ing water quality stan-
dards. Levels ranged
from 34.5 to 205
cfu/100 ml, well below
the single sample thresh-
old of 576 cfu/100 mL
for bacteria in waters
designated for second-
ary contact recreation.
A geometric mean
calculated for the 2011
data showed that the
assessment unit had a
bacteria geometric mean
of 123 cfu/100 mL, which is below the applicable
water quality criterion of 126 cfu/100 mL. On the
basis of these data, DEQ is proposing to remove
the bacteria impairment for the 19.1-mile assess-
ment unit ID17040210SK010 _ 04 from the state's
2012 list of impaired waters. The assessment
unit remains listed as impaired for temperature
and sediment. Monitoring has not yet been com-
pleted in the adjacent (upstream and downstream)
impaired assessment units (ID17040210SK010 _ 04
and ID17040210SK008 _ 04); therefore, these will
remain listed as impaired.
Figure 2. Raft River at the Narrows,
before (top) and after (bottom) BLM
installed exclosures to limit livestock
access to the river.
Partners and Funding
Major partners have included DEQ, the Idaho
Department of Agriculture, the Idaho SWC, IASCD,
the East Cassia SWCD, the Forest Service, NRCS,
BLM and local landowners. Key funding sources
have included a $281,333 CWA section 319 grant
(including $112,515 in local matching funds) and
a $250,041 Water Quality Program for Agriculture
grant from the Idaho SWC (including $62,510 in
local matching funds).
ft
i
U.S. Environmental Protection Agency
Office of Water
Washington, DC
EPA841-F-13-001S
May 2013
For additional information contact:
Katie Shewmaker
TMDL Implementation Coordinator
Idaho Department of Environmental Quality
208-736-2190 • Katie.Shewmaker@deq.idaho.gov
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