Water Quality

Improve river water quality to positively impact our natural ecosystem.

When the LA River was channelized, it tackled the issue of flood control, but as the built environment developed and spread to encompass the river and its surroundings, negative consequences for the quality of river water became apparent. First, the surrounding uses  around the river increased pollutants (from streets, industry, urban areas, etc.) mobilized by rainfall that runs over lands and into the drainage systems. And second, through increased urbanization, ground surfaces became impervious and reduced the natural filtering systems that were the Los Angeles area wetlands—in fact, 98% of the original LA River watershed’s native wetlands have been lost.1

The integration of restorative and substantial water quality features, designed to improve water quality, can provide a number of benefits. These benefits include the removal of stormwater pollutants along with multiple other benefits, such as habitat creation, restoration of groundwater recharge, and development of open spaces and recreational areas in upland areas which can improve the quality of life of residents throughout the watersheds.

Water quality priority levels were assigned within the Greater Los Angeles County Region based on catchment-specific characteristics— namely land-use dependent pollutant generation estimates, as well as the catchments’ locations relative to impaired downstream water bodies.



1 Within the Los Angeles Watershed an estimated 100 percent of the original lower riverine and tidal marsh and 98 percent of all inland freshwater marsh and ephemeral ponds have been lost (Stein et al. 2007). – Source: (0519) Wetland and riparian mapping within the rivers and mountains conservancy territory: a landscape profile. 2006. S Dark, DL Bram, M Quinones, LD Duong, J Patananan, J Dooley, M Antos, F Bashir, J Mejia, M Sutula, E Blok. Technical Report 519. Southern California Coastal Water Research Project. Costa Mesa, CA., http://ftp.sccwrp.org/pub/download/DOCUMENTS/TechnicalReports/519_wetland_rip_mapping_conservancy.pdf