Page 97 - Beaumont Basin Watermaster - DRAFT 2016 Annual Report
P. 97
OSWDS is estimated between 1,700 and 3,100 ac-ft/yr. representing 13 to 21 percent
of total recharge to the BMZ.
At 4,900 lots, the contributions from OSWDS will significantly impact water quality to
the point that well head treatment will be required at certain well locations in order to
meet drinking water standards. At 8,800 lots, the contributions from OSWDS will
rendered the entire BMZ non-potable.
Left unmitigated, OSWDS discharges will contribute enough nitrate to exceed the
Basin Plan objectives for the BMZ.
There is sufficient evidence of groundwater contamination by OSWDS to warrant the
Regional Board to issue a prohibition on new OSWDS in the CVCOI.
According to WEI, as a result of this investigation, the County of Riverside issued a
moratorium, followed by a permanent prohibition on the installation of septic systems in Cherry
Valley unless the septic system is designed to remove at least 50 percent of the nitrogen in the
wastewater. In 2009, the County passed a new ordinance that removed the prohibition on
conventional OSWDS. WEI further indicates that the Regional Board initiated a process in
2009 that may lead to amending the Basin Plan prohibiting conventional OSWDS and
regulating the discharges to meet antidegradation objectives.
Summary of University of California, Riverside Study
This study is titled: “Water Quality Assessment of the Beaumont Management Zone: Identifying
Sources of Groundwater Contamination Using Chemical and Isotopic Tracers” (UCR, 2012).
The study divides the BMZ into four distinct zones; their location is depicted in Figure 2 of the
UCR report (not included here). A brief description of the zones is as follows:
Zone 1 – Region Influenced by Wastewater Treatment Plant Effluent. This zone occupies the
southernmost area of the BMZ. Water quality in this zone is influenced by effluent from the
City of Beaumont wastewater treatment plant.
Zone 2 – Wildland and Low Density Septic Disposal Region. This zone is defined as the area
uphill of Edgar Canyon to the north of Cherry Valley. Water quality in this area had low to
moderate concentrations of TDS and nitrate.
Zone 3 – Urban Region with On-site Septic Disposal Systems. This zone overlies the Cherry
Valley area including the area around the Noble Creek and Little San Gorgonio Spreading
Ponds. Human waste from homes and business in this zone is primarily disposed of in on-site
waste disposal systems.
Zone 4 – Urban Region with Consolidate Sewer System. Zone 4 comprises those portions of the
City of Beaumont utilizing a municipal wastewater system.
The UCR report attempted to answer a series of questions; the questions and a summary of
their response is provided below.
Beaumont Basin Watermaster 2016 Annual Report – DRAFT – August 2017 4-5
