Monitoring the Condition of Streams in the San Gabriel River Watershed Using Multiple Indicators

In 2004, a group of local, state and federal stakeholders formed the San Gabriel River Regional Monitoring Program (SGRRMP) to integrate and expand monitoring efforts in the San Gabriel River watershed. Since 2005, The SGRRMP has performed rigorous, scientific monitoring during dry weather using multiple indicators (biological, chemical, and toxicological) to assess stream condition throughout the watershed. Benthic macroinvertebrate communities are biological indicators that were relatively undisturbed in the San Gabriel Mountains compared to the much more disturbed communities in the highly urbanized lower watershed and mainstem channel. The least disturbed physical habitat in the upper watershed supported the “healthiest” aquatic invertebrate communities. Toxicity was observed in the upper watershed locations and was never observed in the highly urbanized mainstem. Aquatic chemistry indicated that attainment of Basin Plan objectives was typically achieved throughout the watershed. The SGRRMP has successfully shown that an integrated watershed monitoring program can provide context to these essential management questions, while improving monitoring efficiencies.