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samples indicates the possibility that septic systems are contaminating groundwater within the
central part of Cherry Valley.
3.- How much nitrate from human waste is making its way into the groundwater of the BMZ?
The report documents the following findings:
Mixing models suggest that between 18 to 30 percent of the nitrate in central Cherry
Valley groundwater is derived from septic systems.
If septic systems were completely phased out, nitrate concentrations in central Cherry
Valley groundwater could decline by 30 percent once a steady state condition is
achieved. The time to reach a steady state is anticipated to be shorter than in other
portions of the BMZ due to relatively high rates of recharge in Zone 3.
Mass balance calculations show that nitrate-nitrogen inputs from septic systems is one
of the largest inputs of nitrogen to groundwater in the BMZ.
If the waste from septic tanks were to be conveyed to the City of Beaumont WWTP,
about 30 percent of the current input of nitrate from human waste to groundwater
would be removed.
4.2 Comparison with Federal and State Drinking Water
Standards
The California Department of Health Services (CDPH) maintains an active water quality
database of all public and private drinking water wells throughout the state. This database,
available at CDPH’s website, was assessed for the 2013-2017 reporting period for 20
domestic production wells in the Beaumont Basin. The objective of this analysis was to
determine whether any of these potable wells had exceeded the Primary or Secondary
Federal and State standards or the notification levels set by the state. Federal standards are
set by the United States Environmental Protection Agency (USEPA) while state standards in
California are set by CDPH. Primary standards at the federal and state level are enforceable
criteria that have been established to protect the public against consumption of drinking water
contaminants that present a risk to human health. Secondary standards are not enforceable
standards; they have been established for aesthetic qualities of water, such as taste, color,
and other. Contaminants with a secondary MCL are not considered to present a risk to human
health at the established maximum level. Notification levels (NL) are not enforceable
standards; however, they require that municipal water suppliers notify the public if the NL for a
chemical has been exceeded.
A total of 1,266 water quality results were extracted from the CDPH database for the 20
production wells in the Beaumont Basin. Results were obtained for 176 analytes sampled
between 2013 and 2017. The results of the analysis indicate that not a single production well
exceeds either the primary or secondary federal and state standards during the reporting
period. However, the California Notification Limit for Vanadium (100 ug/day) was exceeded
once at SMWC Well No. 4 during the reporting period.
Additional water quality information from 2012 through 2016 was obtained from Dudek
Engineering as part of the Maximum Benefit Monitoring Program. A total of 1,356 water
Beaumont Basin Watermaster 2017 Annual Report – DRAFT – February 2018 4-7
