Key stressors to the biological condition in streams can include increased concentrations of nutrients, dissolved metals, and organic chemicals. To investigate the influence these contaminants might have on stream health in the San Gabriel River Watershed, groups of these analytes were collected simultaneously with the BMI samples. A complete list of measured constituents can be found in the Project QAPP.

To determine if any of the constituents were measured in concentrations that might be of environmental concern, where possible, their concentrations were compared against established regulatory standards.

Click on the links on the right to explore the proportion of water samples that exceeded regulatory standards for each region of the San Gabriel watershed.

Combined Water Quality represents the proportion of regulatory exceedances for nitrate, copper and selenium combined over the period beginning in 2014 thru 2018. These were the only constituents that exceeded regulatory standards making this assessment conservative since numerous other water quality parameters were measured, but did not exceed any standard. No organic constituents (pyrethroids, orthophosphate pesticides) are presented because there were very few samples that were above the analytical detection limits over the period.