OOS 12-4
The state of the Los Angeles River watershed: 2008-present
The Los Angeles River Watershed Monitoring Program (LARWMP) was one of the first watershed-wide monitoring efforts initiated in California combining a multilevel, probabilistic (ambient) monitoring design with targeted sampling. LARWMP is designed to answer five key monitoring questions: What is the ambient condition of streams?; Are conditions at unique habitats changing over time?; What are water quality conditions near major discharges?; Is it safe to swim?; and, Is it safe to eat fish? Sampling for these programs has included six annual summer surveys that commenced in 2008. To date, LARWMP has collected and analyzed samples from 60 probabilistic sites, 4 target sites and 9 unique habitat sites annually, 800 samples for fecal indicator bacteria (FIB), and over 50 fish tissue samples.
The overall condition of streams in the watershed is based on a probabilistic monitoring design using a combination of indicators that include water quality, toxicity, bioassessment, and physical habitat parameters. The California Rapid Assessment Method (CRAM) was used to assess changes in habitats of unique interest. The water quality conditions in receiving waters near three major NPDES discharges was assessed by comparing monitoring data against state and federal standards. Fecal indicator bacteria (FIB) were collected during summer months at popular lake and river recreation areas to assess swim safety. Fish consumption safety was assessed by measuring the concentrations of mercury, selenium, DDT and PCB in tissues from fish collected at popular angling sites.
Results/Conclusions
Results to date illustrate clear patterns in stream condition that distinguish the upper (un-developed) portions and lower (developed) portions of the watershed in terms of water quality and habitat condition stressors. There have been few exceedances of water quality standards in receiving waters near NPDES discharges during the period. Bacterial levels were elevated at public swimming sites, particularly on weekends and holidays when human visitation was the highest. Contaminant concentrations in fish tissues have helped identify species that exceed state consumption thresholds and will be used by the state to determine where fish advisory postings might be needed. These results have been presented to watershed managers, regulators, the public, politicians and the media through a State of the Watershed report and symposium, annual summary reports and a web based data portal.