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I M* I NONPOINT SOURCE SUCCESS STORY
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historic mining activities in the watershed, and the
widespread recreational use of OHV on the many miles
of abandoned roads in the watershed, with rain events
introducing additional mercury to the waterbodies via
sediment ioading.
Story Highlights
In 2007 BLM updated the Clear Creek Management
Area (CCMA) Resource Management Plan (RMP). The
BLM closed roads that were heavily used by OHVs and
implemented erosion control measures including, as
noted in the RMP, using native soil and vegetation to
improve slope stability and mitigate erosion. Fences
and barriers were constructed to preclude access to
riparian areas and closed areas to prevent OHV distur-
bance and off-site transport of metals and sediment.
Abandoned mines in the area were also identified for
remediation (see Figure 1). This included the removal
of thousands of cubic yards of mercury waste rock and
soils. All unearthed mining debris was removed as well.
The removed rock, soils and debris were deposited
into a nearby repository.
Results
Since the historic mines remediation and the closure
of the area to OHV use, the TMDL numeric target has
been met in Clear Creek. Monitoring data collected
since 2007 (by both the BLM and the Central Coast
Regional Water Quality Control Board) shows that mer-
cury levels are currently meeting water quality targets
and that mercury toxicity is no longer a threat for
aquatic life or human health. Water quality monitor-
ing data collected between 2007 and 2013 showed
no exceedances for mercury (Figure 2). Clear Creek
was removed from the impaired waters list in 2016.
Hernandez Reservoir remains listed as impaired.
Partners and Funding
The California Central Coast Regional Water Quality
Control Board (CCRWQCB) is responsible for devel-
oping and enforcing water quality objectives in the
central coast of California. The CCRWQCB approved
and adopted a mercury TMDL for Clear Creek and
Hernandez Reservoir in 2004. The Central Coast
Ambient Monitoring Program and Surface Water
Ambient Monitoring Program provided funding for the
monitoring data they collected.
The BLM manages mil.ions of acres of public land.
One of their premier programs maintains an inven-
tory of abandoned mines, many of which have seen
remediation efforts and reclamation actions. The Clear
Creek watershed has many abandoned mines with
naturally occurring mercury and asbestos. The BLM
Hollister Field Office conducted remediation projects
at many of these mine sites, in 2001 the BLM invested
approximately $345,000 to remediate mine sites in the
watershed. Entrance fees for recreational areas within
the Clear Creek Management Area were also allocated
to support the effort.
Clear Creek Hg in Water (Unfiltered)
Date

10
—Mercury in Clear Creek
1
0.1
0.05 ng/L Mercury
0.001
0.0001
Figure 2. Concentration
of mercury in Clear Creek
from unfiltered water
samples (1995 to 2013).
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©
U.S. Environmental Protection Agency
Office of Water
Washington, DC
EPA 841-F-18-Q01O
September 2018
For additional information contact:
Howard Kolb, California Central Coast Regional Water Quality
Control Board
805-549-3332 • Howard.Kolb@waterboards.ca.gov
Mary S. Hamilton, California Central Coast Regional Water
Quality Control Board
805-542-4768 • Mary.Hamilton@waterboards.ca.gov
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