Tahoe Valley – Tahoe South
Statistics
- Basin Name
- Tahoe Valley – Tahoe South
- Basin Number
- 6-005.01
- SGMA Basin Priority
- Very Low
- Critically Overdrafted
- No
- Hydrologic Region Name
- North Lahontan
- Counties
- El Dorado
- Adjacent Basins
-
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At-A-Glance
Located in California’s North Lahontan hydrologic region, the Tahoe Valley – Tahoe South subbasin is 14,800 acres in size. This Very Low priority basin is home to an estimated 25,966 people (2010 value). It has approximately 284 wells, of which approximately 60 are water supply wells. Groundwater accounts for approximately 97.40 percent of the basin’s water supply.
Basin Notes
2004: Bulletin 118 basin description
2007: Groundwater resources survey of the Lake Tahoe basin, U.S. Department of Agriculture (USDA), U.S. Geological Survey (USGS)
2009: Hydrogeology of the Lake Tahoe Basin, U.S. Geological Survey (USGS)
2014: CASGEM basin prioritization – medium. Comment: South Tahoe Public Utility District reports that MTBE has had a major impact on the groundwater within its service area, resulting in 12 of 34 production wells unusable and the destruction of two wells (B-118), (Berghson 2000)
2018: Draft basin priority – Very Low. Comments:
- 1) CASGEM/WDL/GWIDS: Stable hydrographs. Source: DWR
- 2) No available documentation on groundwater level decline past or present in the basin
2018 Final Basin Prioritization: Basin priority remains unchanged at medium priority. Comments from 2018 Final Basin Prioritization: The south “Y” Plume has impaired three PSW (LBWC #3, #5, and TKWC #2) with a combined source capacity of 3.25 MGD. Trace levels of PCE below MCLs is presently detected in one PSW well (TKWC#1); however, PCE concentrations have been steadily increasing in this well during the 2016 WY. Potential impairment of TKWC #1 would further reduce the total production capacity of the area drinking water sources by an additional 1.44 MGD. Two other wells (LBWC #1 and TKWC #3) west of the South “Y” plume are presently non-detect for PCE; however, the combined source capacity of these two neighboring wells is 3.82 MGD and is believed to be at risk for groundwater contamination in the future. This a major challenge for the management of groundwater resources of the basin. Competition for funding and resources for containment/clean-up and a slow but increasing reduction in groundwater storage due to plume expansion puts increasing pressures on sustainability.