Cache Creek Watershed Background

Catfish caught by sport fisherman at Clear Lake, CA. Image: Tom Stienstra, San Francisco Chronicle, 2017

The Cache Creek Watershed, in the map to the left, is:

located north of San Francisco in California’s Coast Range and Sacramento Valley
a sub-basin of the Sacramento River Watershed which drains to San Francisco Bay Delta Estuary.
1,140 square miles with western basin divide elevations in the Coast Range exceeding 4,000 feet (Kamman Hydrology and Engineering 2010).
The headwaters of the Cache Creek is Clear Lake
Clear Lake, known as the Bass Capital of the west, is a warm shallow lake, the largest natural lake entirely within California and one of the oldest lakes in North America (Sacramento River Watershed Program 2017).

Landuse:

Long history of land use by humans dating back 10,000+ years to the Patwan, Miwok and Pomo Native American Tribes
Land use development began in the 1800’s and included livestock grazing, mining then agriculture with towns developing as these land uses developed
Major land uses today:
- Agriculture, Tourism and Recreation that emphasize Fishing, Boating, and Whitewater rafting and Hiking, Gravel Mining, Urban land uses, National Forests and Bureau of Land Management (BLM) lands, among others... (Capay Valley Vision, 2017)

Fisheries in the Cache Creek Watershed are extremely important for:

Subsistence, low-income residents and wildlife as a major protein source.
Economic support from sport fishing and recreation

Climate: Mediterranean

Three main vegetation communities:

Chaparral (50%)
Woodland (20%)
Grassland (15%)

Arbitrary Boundaries:

3 Counties:
- Lake
- Colusa
- Yolo

Historic mercury mining and the use of mercury for gold mining in the Cache Creek Watershed has made the fish unsafe to eat for humans and wildlife

Mercury mining in the Cache Creek Watershed started in the 1860’s and continued through the 1980’s (Suchanek et al., 2010; Jago, 1995; Central Valley Water Board, 2009).
It is estimated that there are about 40 Hg mines in the Cache Creek Watershed.
- Map to the right shows the locations of 17 of those mines.
Imbalances due to Hg and gold mining have materialized as impaired water quality and an overabundance of mercury in the watershed system, resulting in bioaccumulation and biomagnification (Domagalski et al., 2004).
Every major water body and stream in the Cache Creek Watershed is on the Clean Water Act’s 303 (d) list for impaired waters due to dangerous mercury levels in fish including Clear Lake, Cache Creek, Bear Creek and Sulphur Creek (California Water Boards, 2017).
The Cache Creek Watershed is noted to be the greatest contributing source for mercury in the San Francisco Bay Estuary which is also on the 303d list for mercury threshold exceedance in fish (Foe and Bosworth, 2008) (Domagalski et al, 2004).
Mine sites are point sources for high concentrations of Hg in stream sediment which provides the basis for ongoing mercury bioaccumulation and biomagnification (Domagalski et al., 2004; Alpers et al., 2005)

(Data for map: California Department of Toxic Substances Control, 2011)

Aquatic and Riparian Species and Critical Habitats of the Cache Creek Watershed

Clear lake is one of the oldest lakes in North America and the largest lake entirely within California - estimated to be between 1.8 - 3 million years old (Giusti, 2009; Sacramento River Watershed Program, 2017; Winder et al., 2010).
Native aquatic species include:
- Sacramento sucker
- Threespine stickleback
- California roach
- Clear Lake Spittail
- Clear Lake hitch
- Prickly sculpin
- Sacramento blackfish
- Sacramento pike minnow and
- Sacramento perch (Department of Fish and Wildlife, 2017; Thompson et al., 2013).

Table shows fish that are native or endemic to Clear Lake including those that are endangered or now extinct from the lake.

Informations for table: Thompson et al. 2013; University of California Division of Agriculture and Natural Resources, 2017; (Department of Fish and Wildlife 2017.

The fish populations of Clear Lake and the Cache Creek Watershed have changed “drastically” over the last 150 years with decreases in native populations and increases in non-natives such as channel catfish, largemouth bass, brown bullhead, Mississippi silversides, common carp and smallmouth bass, among others (Thompson et al., 2013).
These changes are attributed to changes in land use such as agriculture and resulting water drawdown as well as increased fluxes of sediment and pollutants, water diversion such as dams and the weir at the settling basin, the application of dichloro-diphenyl-dichloroethane (DDD), introduction of non-native fish, and mining (Thompson et al., 2013).

Other species of concern in these critical habitats include the Southern Bald Eagle and Golden Eagle, which are protected under the Bald Eagle and Golden Eagle Protection Act, the Yellow-billed Cuckoo, Swainson's Hawk and the Peregrine Falcon (Department of Fish and Wildlife, 2017).

Historic mercury mining and the use of mercury for gold mining in the Cache Creek Watershed has made the fish unsafe to eat for humans and wildlife

Southern Bald Eagle

Credit: Dennis Demcheck, U.S. Geological Survey. Public domain.

Photo: Gary Botello;

https://www.nps.gov/articles/western-yellow-billed-cuckoo.htm

Yellow-Billed Cuckoo

More Endangered or Threatened species of these Critical Habitats in the

Cache Creek Watershed.

Birds, amphibians and invertebrates are important members of the food web threatened by the neurotoxicity of mercury

Photos: (International Union for Conservation of Nature 2017) (www.calflora.org) (US Fish and Wildlife Service 2014) (Seago 2008) (Southern Sierra Research Station 2012) (Sacramento Fish and Wildlife Service 2017) (Department of Fish and Game 2017).