Section 319
NONPOINT SOURCE PROG
M SUCCESS STORY
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Restoring Stream Channel and Floodplain Reduces Turbidity
\A/„._	i.	~	Past placer mining (the mining of loose soils arid sediment for
Waterbody Improved . , . . A, . , r> ,y n . i+ .. , ,
7 r	minerals) along Alaska s Caribou Creek resulted in reduced
sinuosity, a non-functioning floodplain, and loose-sediment tailings piles throughout the
floodplain that reduced riparian function. Erosion of unstable areas created high levels of
turbidity that violated water quality standards, prompting the National Park Service (NPS) to
suggest that the Alaska Department of Conservation (ADEC) add Caribou Creek to the Clean
Water Act (CWA) section 303(d) list in 1994. In 2002 NPS and other partners began restoring
the damaged portions of Caribou Creek by removing tailings and restructuring and replanting
the floodplain. Monitoring in 2009 showed that Caribou Creek met the turbidity water quality
standard. Additional restoration activities in 2010 improved the creek further. As a result, ADEC
removed Caribou Creek from the CWA section 303(d) list in 2010.
Problem
Caribou Creek (Figure 1) is in Denali National Park
and Preserve in south-central Alaska's Kantishna
Hills. In the early 1900s, individual miners flocked to
streams in the Kantishna Mining District—including
Caribou Creek—to seek their fortunes. Miners
began dredging Caribou Creek for gold in the 1930s.
Over the years, mining techniques became more
aggressive and destructive. By the 1970s and 1980s,
miners were using bulldozers to move streambed
materials through large-scale hydraulic wash plants
to separate gold flakes and nuggets from other
streambed materials. The companies left long rows
of eroding tailing piles in the floodplain (Figure 2)
and eroding stream banks that remained devoid of
vegetation. By 1990, Caribou Creek had the most
extensive placer-mining-related damage of any
drainage in Denali National Park and Preserve—361
acres comprising 13.1 miles of damaged aquatic and
riparian habitat. Some miners restored their claims
upon completion of the mining, but others did not.
Eroding sediment from the damaged areas of the
Caribou Creek watershed produced high levels of
turbidity. Data from the early 1980s showed that tur-
bidity exceeded water quality standards 64 percent
of the time. These data, combined with best profes-
sional judgment concerning ongoing disturbances
from past placer mining, prompted NPS to request
that ADEC consider Caribou Creek impaired. On the
basis of this request, ADEC added a 16.1-mile-long
segment of Caribou Creek to the 1994 CWA section
303(d) list of impaired waters for turbidity.
Figure 1. Caribou Creek flows through south-
central Alaska's Kantishna Hills.
Figure 2. Before reclamation efforts, piles of
tailings covered the Caribou Creek floodplain
and restricted creek flow.

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Figure 3. Caribou Creek in 2002 after NPS leveled
and contoured large tailings piles to restore natural
channel meanders and riparian function.
Project Highlights
Caribou Creek flows within the present-day
boundaries of the Denali National Park and Preserve.
Congress created Denali National Park in 1917 as Mt.
McKinley National Park. In 1980 Congress approved
the Alaska National Interest Lands Conservation
Act, which enlarged the park to 6.1 million acres and
renamed It Denail National Park and Preserve.
A 1985 court order imposed an injunction on
mining in the Kantishna Mining District pending an
Environmental Impact Statement (EIS). After the EIS
was completed in 1990, NPS proceeded to acquire
many valid mining claims. As NPS acquired mined
lands, it evaluated the areas for possible restoration
activities. By 2001, NPS was ready to begin
restoring Caribou Creek.
Between 2001 and 2010, NPS removed hazardous
materials and equipment from five former mining
claim areas, removed an abandoned airstrip, leveled
and contoured large tailings piles to restore natural
channel meanders (Figure 3), installed coir (coconut
fiber) logs, and reestablished vegetation to control
erosion.
In 2010 NPS implemented additional restoration
efforts with the help of contracted specialists
at Hydraulic Mapping and Modeling (design).
Environmental Compliance Consultants and Oasis
Environmental (construction). They widened and
smoothed the upper portion of the disturbed
fIoodplain (last mined in the mid-1980s), creating a
relief channel for flood events. They also reinforced
some previously restored curves in the main
channel of Caribou Creek (Figure 4).
Figure 4. In 2010 NPS reinforced previously restored
curves in the main channel with coir logs (back-
ground) and rock vanes (foreground).
Results
As a result of the restoration efforts, erosion and
turbidity levels in Caribou Creek declined. Alaska's
water quality standard required that turbidity not
exceed 5.0 nephelometric turbidity units (NTU)
above natural conditions when the natural turbidity
is 50 NTU or less. Monitoring data collected monthly
in Caribou Creek's headwaters and near the mouth
from June through September of 2009 and 2010 by
USGS show turbidity levels consistently iess than
2.0 NTU, well within the water quality standards.
In addition, in 2009 NPS performed follow-up
topographic monitoring at seven cross sections
of the stream channel. The agency also surveyed
channel locations and sinuosity with a global
positioning system. After analyzing USGS water
quality monitoring and stream channel data, NPS
concluded that the creek is meeting the turbidity
standard. On the basis of that information, ADEC
removed Caribou Creek from the 2010 CWA section
303(d) list of impaired waters for turbidity.
Partners and Funding
NPS implemented restoration efforts, worked with
the U.S. Geological Survey to track the progress
of the water quality recovery, and shared the data
with ADEC and the U.S. Environmental Protection
Agency. Approximately $185,000 in NPS Natural
Resource Preservation Program funding supported
data collection, project planning and design, and
project implementation efforts in 2000-2002.
Denali Park and Preserve received another $2.5 mil-
lion in NPS funds in 2008-2010 for iarge-scale
restoration efforts in Caribou Creek and other
waterbodies in the Kantishna Mining District.
«	U.S. Environmental Protection Agency
$	Office of Water
I	& Washington, DC
\W/
EPA 841-F-11-001P
PR0	February 2011
For additional information contact:
Brock Tabor
Alaska Department of Environmental Conservation
907-465-5023 • brock.tabor@alaska.gov
Guy Adema
Denali National Park and Preserve
907-683-2294 • guy_adema@nps.gov

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