TMDL Project Overview
Background
The Los Angeles Regional Water Quality Control Board (Regional Board) and the Sanitation Districts of Los Angeles County (Sanitation Districts) are jointly developing and performing a number of technical studies required by the Upper Santa Clara River Chloride Total Maximum Daily Load (TMDL).
On May 6, 2004, the Regional Board adopted an amendment to the Water Quality Control Plan (Basin Plan) for the Los Angeles Region to revise the interim wasteload allocations and Implementation Plan of the Upper Santa Clara River TMDL. The Implementation Plan includes four major studies:
- Agricultural Chloride Threshold Study:
An evaluation of the scientific evidence regarding decisions on the appropriate chloride threshold for the protection of sensitive agriculture. - Groundwater Surface Water Interaction Model:
Development of a model to determine the interaction between surface water and groundwater. - Endangered Species Study:
An evaluation of the scientific evidence regarding the appropriate chloride threshold for the protection of endangered species. - Site Specific Objectives and Anti Degradation Analysis:
An anti-degradation analysis and an analysis of site specific chloride objectives that may be proposed to protect beneficial uses of the river.
The Collaborative Process
The Collaborative Process was developed to implement the Chloride TMDL in the Upper Santa Clara River. The Regional Board and the Sanitation Districts are jointly performing these studies to ensure that, by the end of the process, there is substantial agreement by Regional Board staff, Sanitation Districts’ staff, and other major stakeholders that there is sufficient and credible scientific and technical information upon which to base decisions about standards and the Implementation Plan for the Upper Santa Clara River. The Regional Board and Sanitation Districts have jointly developed a collaborative plan that lays out the framework for conducting and managing these studies, including decision making, dispute resolution, stakeholder involvement, partnering, and facilitation.
Click here to see the complete Upper Santa Clara River Chloride TMDL.
Click here to see other Upper Santa Clara River TMDL documents.
The studies will be co-managed by Regional Board and Sanitation Districts' staff. Each study will be subject to technical review by outside experts. Additionally, key external stakeholders (such as water districts, agriculture, and environmental groups) are invited to participate in the working groups that will oversee the technical studies. The Regional Board and the Sanitation Districts will also conduct separate periodic stakeholder meetings or workshops to discuss significant reports and/or findings for each of the special studies considered. Once these studies are complete, the Regional Board will re-consider the water quality objective, the TMDL Implementation Plan and may revise the water quality objective, as appropriate. The studies will be conducted using a facilitated process. A facilitator is a neutral third-party, who will ensure that meetings and work sessions are conducted in a manner that is fair to all points of view and interests, and utilizes techniques that maximize the team's effectiveness and synergy.
Organizational Structure and Schedule
Implementation of the TMDL is expected to occur within a 13-year period. However, most of the work and studies that could affect the chloride water quality objective and TMDL Implementation Plan will be conducted in the first 5 years of the study, and reconsideration of the objective will occur at the end of this five-year period. Each of the four major studies will have an organizational structure designed to address the issues that have been raised by the Sanitation Districts, Regional Board and other stakeholders regarding environmental protection, scientific rigor, transparency in the process, and stakeholder participation to ensure that all parties' interests are addressed.
The Project Steering Committee has overall responsibility for implementation and oversight of all four special studies.
The Technical Working Groups (TWG) to be developed for each study are tasked with advising and reviewing the work performed by contractor(s) hired for their respective special study. The Regional Board and Sanitation Districts will designate staff members to participate in each of the working groups. In addition, it is anticipated that the membership of the working groups will also include several other interested stakeholder representatives.
The Technical Advisors Panels (TAP) will be made up of individuals with recognized expertise in the area of interest that can provide objective review of the technical adequacy of the study work being performed by the contractor/consultant, and recommendations pursuant to the TMDL Implementation Plan.
The Santa Clara River
The Santa Clara River (SCR) is the largest river system in southern California that remains in a relatively natural state. The river originates in the northern slopes of the San Gabriel Mountains in north Los Angeles County, traverses in a westerly direction into Ventura County, and discharges into the Pacific Ocean through the City of Ventura. The river runs approximately 100 miles from its headwaters near Acton, California, to its outlet in the Pacific Ocean in Ventura County, and drains an area of approximately 1,200 square miles. The river does not flow continuously year round, there are river segments with perennial flows and other river segments have ephemeral flow. The Upper Santa Clara River watershed consists of approximately 680 square miles of mostly natural land with some mixed type developed areas. Much of the development is concentrated in or near the City of Santa Clarita, the only incorporated city in the Upper Santa Clara River watershed.
Between the Saugus Wastewater Reclamation Plant (WRP) and the Los Angeles-Ventura County (LA-VC) line there are gaining and losing reaches within the Santa Clara River, dependent on the aquifer-stream system. The Upper Santa Clara River aquifer-stream system consists of an unconfined alluvial aquifer, which underlies the Santa Clara River and its tributaries. In the upper portion of the Santa Clara River watershed, where the Districts’ WRPs discharge, the river contains surface flows for the majority of the year (i.e., during dry weather conditions) primarily consisting of the effluent discharged from the WRPs. Year round, with the exception of periods during significant rain events, the river is completely dry immediately upstream of the discharge from the Saugus WRP. Also, during the dry months of the year, there are locations in the river between the Saugus and Valencia WRPs where surface flow completely subsides for some period during the day due to the diurnal flow conditions experienced at the Saugus WRP (usually during the very early morning). The surface water at the LA-VC line contains more of the mineral character attributable to the rising groundwater.
Strawberries and avocados have been identified as the two most salt-sensitive crops grown in the SCR watershed. The Santa Clara River also supports populations of, or appropriate habitat for, several endangered fish, amphibians, and plant life. One type of endangered/rare fish, the unarmored three-spine stickleback, resides in some portions of the Upper SCR watershed. Species-specific acute and chronic tolerance levels to chloride for the unarmored three-spine stickleback are unknown. Other endangered species that could occur within the Upper SCR Watershed, such as the Arroyo Toad, Red Legged Frog and riparian species such as the cottonwood, may also be sensitive to salinity at higher levels.
