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NONPOINT SOURCE SUCCESS STORY
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Abandoned Mine Reclamation Restores Yellowstone's Soda Butte Creek
. . . . ,	,	, For over 80 years, abandoned mines and mills near the town of
Waterbodies improved Coote aty have |eached meta|s into upperSoda Butte &eekand
its tributary, Miller Creek. As a result, the Montana Department of Environmental Quality (DEQ)
added both creeks to the Clean Water Act (CWA) section 303(d) list of impaired waters in 1996. Both
the U.S. Forest Service (USFS) and the DEQ's Abandoned Mine Lands Program completed the 5-year
McLaren Tailings Reclamation Project, which reduced pollution and allowed both creeks to attain
water quality standards for aluminum, cadmium, zinc, iron, lead, and manganese. Soda Butte Creek
is also meeting standards for copper. These pollutants are proposed for removal from the 2018 list
of impaired waters.
Problem
Miller Creek flows into upper Soda Butte Creek, which
flows for about 5 miles through southern Montana
before entering Yellowstone National Park (YNP) in
Wyoming and emptying into the Lamar River (Figure
1). In the early to mid-1860s, prospectors found gold
in stream deposits in Miller Creek. Metal deposits of
lead-silver ore from Miller Mountain, gold-copper ore
from Henderson and Fisher mountains, and copper
ore mined near the headwaters of Stillwater River
were processed (in 1934-1953) by the McLaren Gold
Mines Company at the McLaren Mill site on Soda Butte
Creek. The operation produced a total of about 60,000
ounces of goid, 170,000 ounces of silver and 4 million
pounds of copper.
Flooding in the upper Soda Butte Creek basin in 1950
breached the tailings impoundment dam. Years later,
bright orange-red sediments containing elevated
levels of metals were mapped more than 15 miles
downstream near the confluence of Soda Butte Creek
and the Lamar River. Although mining in this area has
largely been abandoned, elevated levels of copper,
lead, iron and manganese were impacting aquatic life.
Surveys in the 1970s showed no trout below the tail-
ings-impacted water. An instream bioassay resulted in
80 percent mortality of fingerling trout after 48-hour
exposure to Soda Butte Creek water. Poor water qual-
ity led the DEQ to add Soda Butte and Miller creeks to
the CWA section 303(d) list of impaired waters in 1996.
in 2002 DEQ developed total maximum daily loads
(TMDLs) and a Water Quality Restoration Plan for the
Cooke City TMDL Planning Area, with help from Custer
Gallatin National Forest.
Map area
WYOMING
New World Mining District boundary
McLaren ^
Mine
2 KILOMETERS
Yellowstone
National
tailings impoundment
Wyoming Creek
MONTANA
Figure 1. The upper Soda Butte Creek watershed is
near the Montana/Wyoming border.
Story Highlights
After the 1988 YNP fires, the McLaren Mill tailings site
was designated as an Emergency Response Action Site
by the U.S. Environmental Protection Agency (EPA),
resulting in work to reduce the amount of water flow-
ing into a tailings impoundment and to improve the
dam's stability. Following the recommendations of the
2002 TMDL studies, the Custer Gallatin National Forest
completed extensive reclamation in the New World
Mining District, including waste removal and reclama-
tion of the Great Republic Smelter site and a portion
of the McLaren Mill site. Given the ongoing discharge
of contaminants from the McLaren Mill site into Soda
Butte Creek and the risk of a catastrophic tailings
dam failure, DEQdecided to remove the tailings

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Figure 2. Soda Butte Creek before (left) and after
(right) restoration.
Figure 3. Miller Creek and Soda Butte Creek both meet
water quality standards (see boxes A, B, and C).
2015
28-30 June
15-17 July
4-5 August
8-9 September
21 October
18 November
2016
25-26 April
17-18 May
2-3 June
13-14 June
28-29 June
impoundment. The 10-acre impoundment, which held
approximately 0.5 million tons of mine tailings and
1 million gallons of contaminated groundwater, was
underlain by a sand and gravel aquifer. Dewatering
the tailings required intercepting uncontaminated
groundwater around the perimeter of the tailings
and pumping contaminated water from the under
the impoundment. The pumped contaminated tail -
ings water was sent to a temporary water treatment
plant. More than 110 million gallons of water were
treated with calcium hydroxide during active reclama-
tion to increase pH and precipitate dissolved metals.
Excavated tailings were amended with quicklime to dry
the tailings for placement in the mine waste repository
and neutralize the acidity of the tailings. About 1,800
feet of stream channels along Soda Butte Creek and
Miller Creek were reconstructed in their approximate
pre-mining locations in 2013. The project site was cov-
ered with compost-amended soil and seeded in 2014.
Results
Water quality has improved (Figure 2). The USFS
monitored surface water quality during the New
World Response and Restoration Project (2000-2010).
In 2015-2016, National Park Service (NPS) scien-
tists teamed with DEQto conduct a comprehensive
characterization of post-reclamation water quality in
Soda Butte Creek. Water and sediment monitoring
were completed at nine sites on 11 occasions in the
basin. USFS data from 2000 to 2010 confirmed that
exceedances of iron and copper were common In Soda
Butte Creek before reclamation. The 2015-2016 NPS/
DEQ investigation demonstrated that reclamation of
the McLaren site effectively eliminated the source of
metals along Miller Creek and the mainstem of Soda
Butte Creek (Figure 3). Both creeks are attaining water
quality standards for aluminum, cadmium, zinc, iron,,
lead, and manganese. Soda Butte Creek (from Cooke
City to the border of YNP) is also meeting standards
for copper. These pollutants are proposed for removal
from the 2018 list of impaired waters. Water quality
data indicate that elevated concentrations of metais
are still found in the basin, but occur along down-
stream tributaries that are unlmpacted by mining or
development.
Partners and Funding
The DEQ Water Quality Division led TMDL develop-
ment, with help from the DEQAbandoned Mine Lands
Program and USFS. Partners in the cleanup effort
Include the Custer Gallatin National Forest, NPS's
Water Resources Division and Greater Yellowstone
Network, YNP, the Montana Department of Natural
Resources and Conservation (DNRC), and DEQ.
Collaboration with Wyoming and EPA helped address
pollutants that flowed from Wyoming into Montana.
The cleanup (including water treatment and site rec-
lamation) cost almost $22 million and was funded by
the U.S. Department of the Interior Office of Surface
Mining Reclamation and Enforcement, and a grant
from DNRC. The project earned two national awards
(2015 and 2016).
Tom Henderson, DEQ's Project Manager for the
McLaren Reclamation Project, passed away suddenly
in October 2018. Tom, who spearheaded the cleanup
and coordinated the data collection for delisting, said
his work on McLaren was the highlight of his career.
Without Tom, none of this would've been possible.
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U.S. Environmental Protection Agency
Office of Water
Washington, DC
EPA 841-F-18-001EE
November 2018
For additional information contact:
Robert Ray, Montana Department of Environmental Quality
406-444-5319 • rray@mt.gov
Mary Beth Marks, U.S. Forest Service
406-587-6709 • mmarks@fs.fed.us
Andrew Ray, National Park Service
406-994-7498 • andrew_ray@nps.gov

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