Surface Water

The Santa Ana Basin occupies ~ 2700 square miles in the Coastal Range Province of Southern California (figure 1). The Santa Ana River is the largest stream system in southern California, beginning in the San Bernardino Mountains (which reach altitudes exceeding 10,000 feet) and flowing more than 100 miles to the Pacific Ocean near Huntington Beach. The watershed is home to over 4 million people, and the population is expected to increase by more than 50% by the year 2020.

The graphic below displays the surface water studies and their approximate site locations.  Some sites were used for multiple studies.

For more information about each study, click on the links below: 

Fixed Site Network: 6 sites: 3 basic fixed sites (BFS) and 3 intensive fixed sites (IFS) were used for continuous monitoring, monthly sampling, and storm-flow sampling from 1998 to 2001.  In addition, biweekly sampling was conducted at the 3 IFS sites from July 1999 through March 2000. The goal of the biweekly sampling was to assess seasonality in the application and transport of anthropogenic compounds in the basin.

TDS and Nutrient Report:  Concentrations of total dissolved solids (TDS) and nutrients in selected Santa Ana Basin streams were examined as a function of water source.  6 fixed sites, 6 mountain sites and more than 20 synoptic sites were sampled.

Pesticides Report: Occurance and Distribution of Pesticide Compounds in Surface Water of the Santa Ana Basin, California, 1998-2001

Nitrate Study on Cucamonga Creek: Algal Productivity and Nitrate Assimilation in an Effluent Dominated Concrete Lined Stream, 2005

Tracer Study on the Santa Ana River: 10 Sites along the Santa Ana River and 5 tributaries were sampled continuously for 24 hours to determine the components of baseflow.

UV Study: An Assessment of Optical Properties of Dissolved Organic Material as Quantitative Source Indicators in the Santa Ana River Basin, Southern California, 2005.

Bed Sediment and Tissue: 12 streambed sediment and fish tissue sites were sampled in 1998 and were used to assess the status of hydrophobic contaminants in the Santa Ana River Basin.

Reservoir Core Study: 4 reservoir sites were cored to asses trace element and organic compound concentrations historically.

Aquatic Ecology: 4 stream sites were selected to conduct ecological studies of fish, invertebrates and algal communities from 1998-2001

Urban Land Use Gradient Study (ULUG): Assessing Water Source and Channel Type as Factors Affecting Benthic Macroinvertebrate and Periphyton Assemblages in the Highly Urbanized Santa Ana River Basin, California, 2005.

Pesticides in Reservoir Study (EPA): One drinking water reservoir (Railroad Canyon) was sampled as part of a nationwide pilot project linking the occurrence of pesticides in drinking water with raw-water sources and to identify watershed characteristics contributing to pesticide contamination.