Nitrate Levels in Groundwater

April 1, 2012

Average concentration of nitrate (mg NO3/L) in wells during the decade 2000 to 2010. Red and deep red indicate wells that are over the MCL (maximum contaminant level). Yellow indicates wells that are above one half the MCL.A draft UC Davis report on nitrates in groundwater released March 13 may lead to higher costs and new regulations on nitrogen fertilizers.

The State Water Board commissioned the report in response to mandates from the state legislature that it develop recommendations to address the issue of nitrate contamination in groundwater in the Tulare Lake and Salinas basins.

Conducted by the UC Davis Center for Watershed Sciences, the study reviewed available data to determine the extent of nitrate contamination, past and present sources, and recommends possible solutions for cleaning up contaminated drinking water, especially in poorer communities.

The report clearly points to agricultural fertilizers and dairies as the two major contributors to nitrate groundwater contamination. It also finds that drinking water in a number of communities exceeds federal drinking water standards for nitrates.

While the report makes it clear that there is no quick solution to the issue, it recommends possible mitigation measures that would impact almonds, which, as a quality protein crop, is a high user of nitrogen.

The report suggests that additional taxes should be placed on nitrogen fertilizers to provide an incentive for growers to apply less N in the field, and to help fund short-term efforts to get clean drinking water to affected communities. It also recommends more extensive reporting requirements through fertilizer use reporting or a documented nutrient budgeting approach.

The report will influence regulations currently being finalized for groundwater waste discharge through the Irrigated Lands Program.

State law SBX2 1 requires the Central Valley Regional Water Board and the Central Coast Regional Water Board to implement recommendations within two years of the report being finalized. However, the State Water Board is planning to hold a public workshop in Sacramento May 23 at 9 a.m. before finalizing the recommendations to the state legislature sometime in 2012.

For full details of the report, go to the UC Davis Groundwater Nitrate website or visit the State Water Resources Control Board website for details about the May public workshop.

Newsletter: 
Outlook
Categories: