Los Angeles County’s Stormwater Monitoring Program Overview

By: Wendy Wert, LABS Vice President

On July 22, 2010, the California Water Environment Association (CWEA) Los Angeles Basin Section (LABS) presented an overview of Los Angeles County’s Stormwater Monitoring programs.    The featured speaker was Oliver D. Galang, P.E., Section Manager with the Los Angeles County Department of Public Works’ Watershed Management Division.  Oliver described the Los Angeles County’s existing National Pollutant Discharge Elimination System (NPDES) Stormwater Program and provided an update of efforts to modernize and expand these into a systemwide water quality monitoring system.

The evenings featured speaker, Oliver D. Galang, P.E. is the Section Manager of with the Los Angeles County Department of Public Works’ Watershed Management Division, who oversees the Stormwater Monitoring Programs on behalf of the Los Angeles County Flood Control District and the unincorporated areas of the County of Los Angeles.  He has over sixteen years of civil engineering experience, including drainage design, project management, planning instrumentation, telemetry systems, and control systems for flood control and water conservation facilities. 

Oliver initiated the presentation with a brief overview of the Los Angeles County Flood Control District (District).  The District was established in 1915 to provide flood protection infrastructure with the primary objectives of flood risk management and water conservation.  The District serves an area greater than 3,000 square miles.  Major components of the flood control system include 15 major dams, 500 miles of open channel, 2,800 miles of underground storm drains and over 120,000 catch basins. 

In 2001 the current NPDES permit for urban stormwater discharges from municipal separate storm sewer systems (MS4) was issued to the following Permitees: the District (lead), County of Los Angeles, and the 84 incorporated cities within the region with the exception of the City of Long Beach.  One of the requirements of the permit, these agencies is required to establish a Stormwater Quality Management Program, which has associated monitoring and reporting requirements.  As the Lead, the District is required to implement a Monitoring Program.  The objectives of the monitoring program are to: assess the impacts of urban stormwater runoff to receiving waters, identify sources of pollutants, and evaluate the effectiveness of Stormwater Quality Management Program.  The Core Monitoring Program (CMP) includes monitoring the mass emissions from the District’s seven (7) major watersheds: Ballona Creek, Malibu Creek, Los Angeles River, Coyote Creek, San Gabriel River, Dominguez Channel, and the Santa Clara River. In addition to the mass emission sites, the CMP  also requires tributary monitoring to identify sub-watersheds where stormwater discharges have the potential to cause or contribute to non-attainment of water quality standards.  Since several of these major watersheds are considered high priority, the tributary monitoring has rotated across the: Los Angeles River, Ballona Creek, San Gabriel River, and the Dominguez Channel, which is currently the focus of these activities. 

In addition, there are also several on-going regional monitoring programs that are mandated by current Total Maximum Daily Loads (TMDLs).  The Department of Public Works, also acts on behalf of the Unincorporated Areas of the County of Los Angeles, participates with other TMDL jurisdictional agencies in the following Coordinated Monitoring Programs throughout the County: Santa Monica Bay Beaches Bacteria TMDLs; Marina Del Rey Bacteria and Toxic Pollutants TMDLs; Los Angeles River Metals TMDL; Malibu Creek Bacteria TMDL; and Ballona Creek Bacteria, Metals, and Toxics TMDLs. 

In light of basin activity and complexity, Oliver explained the importance of a regional agency, such as the District, to supplement NPDES/TMDL monitoring programs through more spatial monitoring within the major watersheds.  The goal of the District system wide monitoring program is to develop a State-of-the-Art, Countywide water quality monitoring system using electronic sensors and remote monitoring capabilities.  With that goal in mind the Department of Public Works (lead), on behalf of the District, has obtained the professional services of Brown and Caldwell  to evaluate the District’s monitoring needs; design a real-time, continuous storm water monitoring program; and develop a pilot program to demonstrate the system’s capabilities.  This system will integrate with, and further enhance the existing NPDES permit monitoring requirements. 

The tests required to measure many of the regulated water quality constituents do not lend themselves to an on-line data-logging format.  Therefore, surrogate sensors are proposed to function as indicators of the pollutants for other water quality parameters.  For example, turbidity measurements could be used to suggest the presence of trace metals and possibly bacteria, and electrical conductivity could be used to indicate the possibility of elevated sulfate and chloride concentrations.  In addition, data loggers will measure flow, pH, and water temperature.  The conceptual model consists of three tiers of monitoring.  Tier 1 includes the seven (7) mass emissions stations: Ballona Creek, Malibu Creek, Los Angeles River, Coyote Creek, San Gabriel River, Dominguez Channel, and the Santa Clara River.  Tier 2 would add tributary monitoring at accessible locations with available power supply, and Tier 3 would add sub-tributary monitoring at the more remote locations that do not have a power supply.  The electronic in-line sensor data gathered at these monitoring locations would be relayed back to District headquarters with access provided through a Graphical User Interface (GUI).  The information could be made available for web viewing, which would support assessment of current conditions and recent trends.  It is also envisioned that the time series data could be analyzed with software such as HydSys, currently used by the District for its stream flow gage and rain gage monitoring.  

Oliver concluded with an overview of the programs implementation schedule.  System design documents were completed in December 2009; conceptual design documents were completed in April 2010.  The project is currently in the pilot program phase.  Design plans and specifications will be complete in August 2010.  Construction, contracting and installation of the pilot program are scheduled to begin in December 2010.  Pilot program testing will begin in April 2011.  The System-wide Expansion is projected to occur through July 2013.