Research Areas > Regional Monitoring > Areas of Special Biological Significance (ASBS) Monitoring Program Development

Project: Areas of Special Biological Significance (ASBS) Monitoring Program Development

Background and Objectives

Areas of Special Biological Significance (ASBS) are important water quality protected areas outlined in the California Ocean Plan. State regulations mandate that there shall be no “discharge of waste” into ASBS, and that these areas shall maintain “natural water quality.” Determining natural water quality, however, is not a simple task. This is particularly true at locations where wet weather discharges occur, since many of the potential contaminants carried by urban runoff can also occur naturally in the environment (i.e., suspended solids, nutrients, trace metals, etc.). Given that ocean water quality can change dramatically from place to place and time to time, the best way to obtain a sense of natural water quality is to collect information from reference areas where no human discharges occur. In the case of wet weather runoff, these would be locations with minimal to no human development in the contributing watershed.

The goal of this study is to answer three questions: 1) What is the range of natural water quality at reference locations? 2) How does water quality along ASBS coastlines compare to natural water quality at reference locations? 3) How does the extent of natural quality compare among ASBS with or without discharges? The first question will quantify natural water quality conditions and produce reference thresholds. The third question will quantify the status of ASBS regionally to determine if these marine protected areas are impacted and, if so, the extent of the impact relative to non-ASBS areas. This project will take place as part of the Bight 2008 Regional Monitoring Program.

Status

This study was completed in 2011.

Methods

The focus of this study was on receiving waters in front of wet weather discharges to ASBS. Data on wet weather discharges from developed watersheds were matched with similar data for reference sites (receiving waters in front of discharges from undeveloped watersheds). The sampling design included:

• A variety of reference locations based on differences in watershed characteristics (i.e., size, slope, geology, etc.)
• A variety of storm events based on differences in rainfall characteristics (i.e., rainfall quantity, seasonality, etc.)
• A variety of measurements including suspended solids, nutrients, trace metals, organic contaminants, and aquatic toxicity

Findings

After sampling 35 site-events, the geometric mean concentrations of total suspended solids, nutrients, total and dissolved trace metals, and polycyclic aromatic hydrocarbons in the ocean following storm events were similar between reference drainages and ASBS discharge sites. Concentrations of chlorinated hydrocarbons were not detectable. In addition, no post-storm sample exhibited significant toxicity to the purple sea urchin (Strongylocentrotus purpuratus) near ASBS discharge sites. A reference-based threshold was developed and, despite the similarities in average concentrations, there were some individual ASBS discharge sites that were greater than reference background. Cumulatively across all ASBS, the constituents most frequently exceeding the reference-based threshold were nutrients and general constituents, followed by dissolved and total trace metals.

Partners

Partners on the project included the State Water Resources Control Board; California Regional Water Quality Control Boards; Cities of San Diego, Laguna Beach, Newport Beach, and Malibu; County of Los Angeles; Scripps Institution of Oceanography; University of Southern California; and the US Navy.