Page 107 - Beaumont Basin Watermaster

Section 4

Water Quality Conditions

The purpose of this section is to document the water quality conditions in the Beaumont Basin
during the 2014-2018 reporting period. TDS and nitrate concentrations in the basin are
compared against groundwater quality objectives for anti-degradation and maximum benefit as
established by the Regional Board for TDS and Nitrate (as N) in the Beaumont Management
Zone (BMZ). In addition, water quality concentrations for a number of compounds are
compared against Federal and State Drinking Water Standards. Figure 4-1 depicts all the
wells that have groundwater quality data for the reporting period.

Sources and Availability of Water Quality Information
There are two main sources of data used in the assessment of water quality conditions in the
Beaumont Basin and near surroundings; namely, the California Department of Public Health
database and the Beaumont Management Zone Maximum Benefit Monitoring Program. The
database obtained from the CDPH, which focuses on drinking water sources, contains water
quality information for the 2014-2018 reporting period. Water quality from the BMZ Maximum
Benefit Monitoring Program is not available at the time of this writing
for the Draft report; however, it will soon be available and will be
Water Quality from the BMZ incorporated in the Final report to be presented at the end of March to
Maximum Benefit Program is the Watermaster Executive Committee.
not available and will be
incorporated in the FINAL As a result, the Comparison with Management Zone Objectives
Report described below is for the 2013-17 period and not for the 2014-18
reporting period. This comparison will be updated for the Final
Report

4.1 Comparison with Management Zone Objectives

Groundwater quality objectives for anti-degradation and maximum benefit have been
established by the Regional Board for TDS and Nitrate (as N) in the BMZ, which encompasses
portions of the Beaumont Basin, the Singleton and South Beaumont basins, and limited
portions of Edgar Canyon above the Banning Fault as illustrated in Figure 4-1. The anti-
degradation objectives are based on the historic ambient TDS and nitrate-nitrogen
concentration of 230 mg/L and 1.5 mg/L respectively.

Maximum benefit objectives were adopted by the Regional Board in 2004 at the request of
STWMA and the City of Beaumont to allow for recharge of imported water and the reuse of
recycled water. The maximum benefit objectives, set to 330 mg/L for TDS and 5.0 mg/L for
Nitrate-N, are relatively low compared to other basins and are protective of the beneficial uses
of the Basin groundwater. According to the Basin Plan, salt mitigation will be required once
the ambient TDS and nitrate-nitrogen concentration exceeds the BMZ maximum benefit
objectives.

Beaumont Basin Watermaster 2018 Annual Report – DRAFT - February 2019 4-1