Report: Inland Empire water contains high concentrations of nitrate and perchlorate

RIVERSIDE - One-quarter of Inland Empire aquifers, including basins from which Riverside County public water originates, contain high concentrations of contaminants associated with runoff from industrial activity and human waste, according to a federal study released today.

The U.S. Geological Survey released findings from a statewide assessment of groundwater quality that indicated high concentrations of nitrate in the southern segment of the inland region's aquifer system, while high levels of perchlorate were discovered in 11 percent of wells and moderate concentrations in 53 percent of wells.

Nitrate is the result of agricultural activity, wastewater treatment and septic system leakage. Perchlorate sources include rocket fuel, fireworks, flares and fertilizers, according to the USGS.

The pollutants were uncovered during tests for 300 possible constituents in public water systems throughout the region, federal officials said.

Water samples were taken from untreated supplies in the Upper Santa Ana Valley, San Jacinto and Elsinore groundwater basins, according to the USGS.

''Over a 10-year period, the USGS is characterizing groundwater quality in 120 basins that supply about 95 percent of public groundwater supplies,'' said USGS director Marcia McNutt. ''The new results for the Upper Santa Ana Watershed show where, what, and how much contamination is in the groundwater, focusing attention on improving water quality where it is needed.''

High concentrations of nitrate and perchlorate in drinking water can lead to adverse health effects, according to the California Department of Public Health.

''Results from this study indicate that human activities in industry and agriculture are the primary factors affecting local groundwater quality throughout the Inland Empire aquifer system,'' said Robert Kent, a USGS hydrologist and lead author of the report, to which the California State Water Resources Control Board contributed.

Officials noted that groundwater undergoes treatment and filtering to control contaminants and meet state and local drinking water standards before it is distributed for public consumption.

The complete report is available at http://pubs.usgs.gov/sir/2012/5052/.