 These spectacular rivers begin as countless tributary streams in high mountain forests before they gather their waters in spring torrents that thunder down through steep river canyons. When they reach the Sierra foothills, these impressive rivers are subdued by dams and by diversions that distribute their waters for agriculture, domestic uses, flat-water recreation, and the many other water needs of central California.
In the mountains, these streams and rivers plunge down steep mountainsides or flow quietly through meadows and forests. Their waters are essential for a diversity of wildlife as well as a great variety of recreational opportunities. Yet despite their incredible value for tourism, recreation, and pure water for water supply purposes, many threats to water quality and aquatic habitat cause environmental problems. Hydroelectric dams and diversions have drastically altered the river's natural flows, although CSERC's efforts in recent years have contributed to a number of positive changes in how rivers of the local region are managed.
Deep ruts in poorly maintained roads channel sediment into nearby streams |
But many other human activities threaten water resources of the region. Foremost is the watershed damage caused by over 6,000 miles of roads in the local mountains. Many of those roads are dirt or gravel routes that don't have adequate maintenance by the U.S. Forest Service, private lumber companies, or other land managers. Deep ruts channel heavy storm run-off and cause sediment to wash into streams, clogging the clean gravel needed as spawning habitat for fish or the eggs of some amphibians. Plugged culverts can result in whole sections of roads washing into streams, plus all the contaminants from motor vehicles routinely pollutes down slope waters.
Livestock grazing causes major stream bank damage, plus cattle wastes directly contaminate streams. Water quality sampling by CSERC biologists have proven that once cows are brought into the local national forest, fecal coliform and E coli contamination quickly rises beyond safety standards. Cattle also often denude riparian areas, compact the soil, and cause downcutting in meadows - drying them far more quickly in the hot summer season.
Streambank damage and fecal contamination from livestock are common on the Stanislaus NF |
Dams and diversions consume water that otherwise would stay in the river, providing cool aquatic habitat. The Tuolumne Utilities District, for instance, takes most of the water for its customers from the South Fork Stanislaus River. Yet roughly half of all the water diverted from the river is lost to leaks and evaporation in TUD's old ditch system. Even when water reaches customers, few water users in the region are aggressively conserving water to reduce the amount diverted from natural stream or river systems.
CSERC works on the frontlines on all of these issues -- using science, monitoring, fieldwork, education, and outreach to attempt to defend the precious water resources and scenic watersheds of the Northern Yosemite region.
South Fork Stanislaus Supplies Much of Tuolumne County's Needs
PG&E diverts a large portion of the South Fork of the Stanislaus River’s flow through a ditch system into a power plant on the main stem of the Middle Fork Stanislaus River. Of the water left in the South Fork, PG&E then allows the Tuolumne Utility District (TUD) to take its share for the needs of County residents. That water flows through an elaborate ditch system into Phoenix Reservoir and into treatment plants that serve outlying users.
With new developments now planned or occurring across many parts of Tuolumne County, the demand for water is high. That demand could eventually limit how much water will be available for agriculture. CSERC is working hard with ranchers and others to ensure that agricultural use of water is given its fair share. CSERC is also concerned that enough water will always be left in the South Fork of the Stanislaus to provide for the needs of wildlife and riparian vegetation.
Existing dam at Lyons Reservoir holds water for many Tuolumne County residents |
The aggressive pace of development across the foothills continues to result in less and less water left in streams and rivers for wildlife and riparian plan needs. Whether it is the South Fork of the Stanislaus or other streams and rivers of the region, many different interests want to take water out of the natural system and use it to make money or to benefit their property, their company, or themselves.
Over recent years, CSERC staff has taken water monitoring samples in a few areas of Tuolumne County. The Center’s staff and volunteers also do hands-on restoration projects to reduce contamination of streams and rivers. CSERC’s director attends countless meetings and hearings each year to advocate for water quality and aquatic species, and the Center provides written input for literally hundreds of development, private timberland, or public land projects each year that threaten water resources.
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