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Deep Creek Meets Sediment Water Quality Standard after Years of Work
Problem
The Ill-square-mile Deep Creek watershed is a
tributary of the Missouri River, in central Broadwater
County near Townsend, Montana. The watershed
topography ranges from steeply wooded slopes in the
Helena National Forest portions of the eastern upper
watershed to the fiat irrigated farmlands along the
Missouri river floodpiain boundary.
A loss of riparian habitat, streambank modifications
and destabilization, and flow alterations from water
diversions contributed to the impairment of the creek
for sediment/siltation in 1988. The Deep Creek total
maximum daily load, developed in 1996 to address this
impairment, applies to the middle and lower sections
(20.4 stream miles) below the Helena National Forest
Service boundary (Figure 1).
Project Highlights
Restoration efforts completed between 1990 and
2003 included significant bank erosion work, approxi-
mately 18,500 feet of bank reshaping, vegetative
plantings, and riparian fencing. The Broadwater
Conservation District and Montana Fish, Wildlife and
Parks coordinated the restoration efforts. Beginning
in 2009 the Montana Department of Transportation
engaged in sediment reduction activities along
Highway 12; these are continuing in the upper portion
of the watershed.
A significant flood event in 2011 damaged numer-
ous public and private structures and infrastructure,
destroyed existing bank stabilization projects and fenc-
es, and caused further stream degradation. As a result,
local, state and federal partners launched a renewed
restoration effort in the watershed. In 2012-2013 the
partners assessed the creek and developed The Deep
Creek Watershed Restoration Plan, which provides
recommendations for restoration. This plan focused
on a multifaceted restoration approach to benefit the
stream, iandowners and water users. In fail 2013 the
Broadwater Conservation District appiied to MDEQ's
CWA section 319 program and received a three-year
award (2014-2017) to help implement a number of
these recommendations.
Deep Creek was selected as a National Water Quality
Initiative (NWQI) watershed for the 2014-2.016
timeframe, which provided additional U.S. Department
of Agriculture (USDA) Natural Resources and
Conservation Service (NRCS) resources to address
agricultural concerns. Lidar data was collected in 2014,
and a 100-year channel migration zone map was com-
pleted in 2015. Irrigation improvements, off-stream
watering, alternative source water for crop irrigation,
and additional fencing, riparian re-vegetation, and
10 Miles
\A/atprhnri\/ Imnrnvprl Excesssedimentand habitat degradation in Deep Creek caused by
"	streambank modifications, flow alterations and historical grazing
in riparian areas inhibited the stream's ability to support its beneficial uses. As a result, the Montana
Department of Environmental Quality (MDEQ) added Deep Creek to the state's Clean Water Act (CWA)
section 303(d) list of impaired waters in 1988. Starting in the 1990s, best management practices such as
irrigation improvements, riparian fencing and stream restoration led to improved sediment conditions
in Deep Creek, which prompted MDEQ to remove Deep Creek from the state's impaired waters list for
sediment in 2016.
Figure 1. The middle and lower Deep Creek watershed areas are
covered by a sediment total maximum daily load.

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stream channel work is being accomplished with
numerous partners including Montana Fish, Wildlife
and Parks; the Montana Department of Natural
Resources and Conservation; MDEQ (CWA section 319
funding); and local landowners (see photos).
Results
There have been measurable improvements in
in-stream flow and aquatic life. MDEQ monitored
for sediment/siltation at three sites in the lower Deep
Creek watershed (DC-01, DC-03, DC-05), for low flow
alterations; at seven sites for temperature; and at six
sites for nutrients. Monitoring occurred In 2014,. and
will continue at the same sites and frequency in 2019
and 2024. Broadwater Conservation District monitored
for flow and temperature, and Montana Fish, Wiidiife
and Parks monitored fish counts and redds. Sediment/
siltation monitoring in 2014 showed no excess aggra-
dation of sediment or percent fines In substrate that
would impair spawning habitat or aquatic life.
The applicable targets include (1) the percent fines
less than 6 millimeters (mm) in size should account for
less than or equal to 19 percent of fines and (2) the
percent fines less than 2 mrn in size should account
for less than or equal to 17 percent of fines. With the
exception of one site where the percent fines less than
6 mm in size was 20.9 percent (slightly above target,
likely due to location near the mouth of the creek), all
assessment parameters meet sediment targets. There
was abundant spawning habitats overall, character-
ized by unconsolidated surface layer gravels that were
mostly in the range of 8 mm to 45 mm. On the basis of
these data, Montana removed the sediment impair-
ment for Deep Creek (segment MT41I002_070) from
its impaired waters list in 2016. The creek remains
listed as impaired because of elevated temperatures
and low flow. Nevertheless, there have been marked
improvements in stream flow and in the health of
macroinvertebrate and fish communities during the
critical late summer period.
Partners and Funding
Recent restoration efforts were supported by multiple
partners, including up to $2 million dollars in land-
owner contributions. The Broadwater Conservation
District acted as the CWA section 319 project lead,
using a total of $518,637. Montana Fish, Wildlife and
Parks provided monitoring and funding ($30,000).
Numerous partners implemented projects including
improving irrigation methods (top), installing
alternative water (middle), and restoring flood-
damaged streambanks (bottom).
The Montana Department of Natural Resources and
Conservation provided another $50,000. The USDA
NRCS acted as the NWQ.I Agency Lead, and provided
technical and financial support ($1,500,000). Lastly,
MDEQ provided technical support and funding.
U.S. Environmental Protection Agency
0** Office of Water
\ Washington, DC
I
EPA 841-F-16-001GG
pro^° December 2016
For additional information contact:
Robert Ray
Montana Department of Environmental Quality
406-444-5319 • rray@mt.gov
Denise Thompson
Broadwater Conservation District
406-266-3146 xl04 • denise.thompson@mt.nacdnet.net

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