Indian Creek Reservoir - Phosphorous
The Lahontan Regional Board adopted Basin Plan amendments incorporating a phosphorus TMDL and implementation plan for Indian Creek Reservoir in Alpine County in July 2002. The amendments were approved by the State Water Resources Control Board, the California Office of Administrative Law, and the U.S. Environmental Protection Agency, Region IX in 2003.
Indian Creek Reservoir was constructed in 1969-70 on an ephemeral tributary of Indian Creek, a tributary of the East Fork Carson River. The reservoir was designed to store tertiary wastewater effluent exported from the Lake Tahoe watershed for later use in pasture irrigation and to support a trout fishery. The reservoir became eutrophic during the 1970s and was placed on the Section 303(d) list for eutrophication in the 1980s. It no longer receives wastewater, and its level is maintained with water diverted from the West Fork Carson River and Indian Creek. Concentrations of total phosphorus decreased but remained at levels which the scientific literature indicates will maintain eutrophic conditions, apparently due to internal loading from the sediment. The reservoir has continued to show symptoms of eutrophication including blooms of blue-green algae, low transparency, and depletion of dissolved oxygen in the hypolimnion.
The California Regional Water Quality Control Board, Lahontan Region (Regional Board) staff developed a TMDL for total phosphorus loading to ICR, since phosphorus is believed to be the controlling nutrient for the eutrophication process.
The following beneficial uses are assigned to Indian Creek Reservoir:
- Municipal and Domestic Supply (MUN)
- Agricultural Supply (AGR)
- Groundwater Recharge (GWR)
- Freshwater Replenishment (FRSH)
- Navigation (NAV)
- Water Contact Recreation (REC-1)
- Non-contact Water Recreation (REC-2)
- Commercial and Sport fishing (COMM)
- Cold Freshwater Habitat (COLD)
- Wildlife Habitat (WILD)]