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quality results were analyzed to determine if the water quality at non-domestic wells exceeded
drinking water standards. Drinking standards were exceeded for a limited number of
constituents as follows:

ƒ Nitrate-N – Nine of the 17 monitoring wells sampled for Nitrate-N exceeded the federal
and state primary MCL of 10 mg/L – Total of 98 readings. All of these wells are located
outside the Beaumont Basin.
ƒ pH – Nine of the 16 monitoring wells sampled for pH exceeded the secondary federal
MCL of 8.5 – Total of 77 readings. One of these wells is located in the Beaumont
Basin.
ƒ Total Dissolved Solids – Nine of the 16 monitoring wells exceeded the federal and
state secondary MCL of 500 mg/L – Total of 75 readings. These wells are located
outside the Beaumont Basin.
Appendix E contains summary statistics of the analytical results for the 2013-2017 period for
all chemicals that have a federal or state drinking water standard as reported in the CDPH
website. Information in this appendix will be updated once the Maximum Benefit Monitoring
Program database for CY 2017 is incorporated.

4.2.1 Trace Metals

As indicated earlier, not a single domestic well exceeded either the primary or secondary
federal and state standards during the reporting period. This represents a significant
improvement over previous reporting periods when several wells exceeded the MCL for trace
metals. Trace metals are briefly discussed here and compared to previous reporting periods.

Aluminum. There were 34 water samples taken during the reporting period and tested for
aluminum. Aluminum concentration at all wells was below 50 ug/L, significantly below the
secondary MCL of 200 ug/L. Aluminum above the MCL can add color to water. One well
exceeded the MCL during the FY 2004-08 reporting period.

Arsenic. There were 35 water samples collected and tested for arsenic during the reporting
period. The highest arsenic concentration was observed at SMWC’s Well No. 4; arsenic
concentration at this well has increased from 4.2 mg/L in 2009, to 4.6 mg/L in 2012, to the
highest value of 5.2 mg/L in April 2013. Latest value, recorded in April 2016, arsenic
concentration was down to 4.4 mg/L. One well exceeded the MCL during the FY 2004-08
reporting period.

Iron. A total of 34 water samples were taken during the reporting period and tested for iron. In
most cases iron concentration was below 100 ug/L., which is significantly below the current
secondary MCL of 300 ug/L. However, there is one well that exceeded the MCL during the 2012-
16 period; BCVWD Well No. 3 at 450 mg/L. Iron at a concentration above the MCL can impact
color, odor, and taste in water. Five wells exceeded the MCL during the FY 2004-08 reporting
period.

Lead. There were 34 water samples collected and tested for lead during the reporting period. The
highest concentration reported were 0.0065 mg/L at BCVWD Well No. 25 and 0.0058 mg/L at
Rancho Calimesa Mobile Home Park Well No. 1. Both of these concentrations are significantly

Beaumont Basin Watermaster 2017 Annual Report – DRAFT – February 2018 4-8