Martis Valley Groundwater Management Plan - Placer County Water ...

Martis Valley Groundwater Management Plan Section 2
Figure 2-17 is a cumulative frequency plot derived from DWR data, and shows the number of public and
domestic wells drilled at various depths in the MVGB. These data show that the vast majority of
domestic wells drilled in the area are relatively shallow, with 50% of domestic wells being installed at
depths of 300 feet below ground surface or less, while the public production wells range widely in depth.
Figure 2-17. Depth Distribution of Wells in the Martis Valley Groundwater Basin
2.7 Groundwater Quality
Groundwater quality in the MVGB is generally of good quality and is currently monitored as part of the
agencies’ agreements with DPH. Each agency releases an annual water quality report for their service
areas in the MVGB; the 2011 annual reports are included in Appendix E. The USGS carried out
groundwater monitoring activities in the MVGB in cooperation with the California State Water Resources
Control Board (SWRCB) as part of the California Groundwater Ambient Monitoring and Assessment
(GAMA) Program (Fram and others, 2007), and sampled 14 wells in the MVGB for a wide range of
constituents during summer 2007. The concentrations of most constituents detected in these samples
were below drinking-water thresholds, with some exceptions: a) concentrations of arsenic were above
the Maximum Contaminant Level (MCL) in 4 of the 14 wells sampled, and b) manganese concentrations
were elevated above the MCL in one well. Arsenic levels above the MCL have also been reported by the
TDPUD.
The T-TSA operates a water reclamation plant which includes the discharge of tertiary-treated effluent
into glacial outwash and Prosser Formation alluvium downstream of the Town of Truckee on the south
side of the Truckee River. Hydrogeologic investigations in the vicinity of the plant indicate that effluent
flows laterally toward the Truckee River and Martis Creek, discharging to these water bodies after a
DRAFT for review purposes only. Use of contents on this sheet is subject to the limitations specified at the end of this document.
P:\40000\140691 - PCWA Martis Valley GWP\GMP\Report\3rd Draft\Martis Valley GMP Draft 01-09-13.docx
2-26