What is a Salt and Nutrient Management Plan (SNMP)?
The need to develop SNMPs for groundwater basins in California began in 2009 when the State Water Resources Control Board (State Water Board) adopted the Recycled Water Policy (2009 Policy). The purpose of the 2009 Policy was to encourage increased use of recycled water while meeting state and federal water quality laws. To accomplish this, the 2009 Policy included a requirement to prepare SNMPs so “salts and nutrients from all sources be managed on a basin-wide or watershed-wide basis in a manner that ensures attainment of water quality objectives and protection of beneficial uses.” The 2009 Policy recognized that all groundwater basins are different in size, complexity, and other factors. It is important that there are locally driven stakeholder efforts to address the region-specific conditions.
In December 2016, the State Water Board adopted Resolution No. 2016-0061 which directed staff to propose amendments to the 2009 Policy, in part, to improve the SNMP guidelines based on lessons learned over the first seven years of implementation. Key amendments include:
- revision of goals and mandates for statewide use of recycled water,
- clarification of recycled water monitoring and reporting requirements,
- recommendations the development of representative, basin-wide groundwater monitoring networks, and
- evaluation the frequency of priority pollutant monitoring in recycled water (2018 Policy).
The State Board adopted the 2018 Policy in December 2018, and it went into effect in April 2019 following adoption by the Office of Administrative Law.
What is the CV-SNMP?
The Coachella Valley Salt and Nutrient Management Plan (CV-SNMP) will result in a basin-wide plan to manage salts and nutrients in compliance with the 2018 Policy.
Why are we updating the CV-SNMP?
In 2015, Coachella Valley Water District, Desert Water Agency and Indio Water Authority submitted a CV-SNMP (as required by the 2009 Policy) to the Regional Water Board (2015 CV-SNMP) for approval. On February 19, 2020, following the adoption of the 2018 Policy, the Regional Water Board provided their findings on the 2015 CV-SNMP along with their recommendations to address five areas:
- Developing an adequate monitoring program to characterize the spatial and vertical distribution of water quality conditions with a plan to identify and fill any data gaps.
- The use of a simple mass-balance model to estimate current and future ambient salt and nutrient (N/TDS) concentrations for the management zones.
- The use of only the secondary upper MCL of 1,000 mgl for TDS to assess assimilative capacity in the absence of numeric objectives for TDS.
- The lack of an antidegradation analysis to support salt and nutrient loading from sources other than recycled water, including the use and recharge of imported Colorado River water.
- The absence of an implementation plan for measures to manage salt and nutrient loading from Colorado River water.
The Regional Water Board encouraged the local water and wastewater agencies to restart the process of developing a SNMP to sustainably manage salts and nutrients from all sources. In response, the CV-SNMP Agencies worked with Regional Water Board staff to develop an accepted CV-SNMP Development Workplan that defines the technical approach and schedule to prepare an updated CV-SNMP.
CV-SNMP Development Workplan
The CV-SNMP Development Workplan is the guide for updating the CV-SNMP to comply with the 2018 Policy and address Regional Water Board recommendations on the 2015 CV-SNMP.
The CV-SNMP Development Workplan includes an updated groundwater monitoring program and a technical scope-of-work to update the 2015 CV-SNMP and recommend numeric TDS objectives across the groundwater basin. The Regional Water Board accepted the CV-SNMP Development Workplan in 2021.
The proposed technical scope-of-work for the CV-SNMP Development Workplan includes:
- Characterize N/TDS Loading to the Groundwater Basin
- Characterize Current Groundwater Quality
- Delineate Draft Management Zones and Describe Metrics to Characterize Beneficial Use Protection
- Develop Technical Approach for Forecasting N/TDS Concentrations in Groundwater
- Construct N/TDS Forecasting Tools and Evaluate the Baseline Scenario
- Forecast N/TDS Concentrations for CV-SNMP Scenarios
- Characterize and Compare the Cost of Baseline and CV-SNMP Scenarios
- Prepare Final CV-SNMP
CV-SNMP Update Schedule