San Joaquin Valley Drainage Monitoring Program 2006 – 2010

This report shares valuable information about agricultural drainage water in order to increase the understanding of its potential impacts and improve its management in the San Joaquin Valley.

The Drainage Monitoring Program is a cooperative effort of State, federal, and local agencies.  Program staff collect, assemble, review, evaluate, and disseminate data on both the quality of drainage water as well as the depth of shallow groundwater in the San Joaquin Valley.  Fifty-two drainage sump systems are monitored for flow, sodium, sulfate, total dissolved solids, selenium, and other constituents.  Staff also combine the Department of Water Resources’ data with data from over 10 other agencies for this report.

DWR used depth information, gathered from approximately 1200 shallow groundwater wells, to draw Present and Potential Drainage Problem Areas Maps for the period from 2006 through 2010.  These maps show over one million acres of potentially impacted lands.  Data provided by several agencies, including the Buena Vista Water Storage District, Central California Irrigation District, Firebaugh Canal Water District, Kern County Water Agency, Panoche Water and Drainage District, San Luis Canal Company, Westlands Water District, and DWR was combined to create the maps.

DWR also drew electrical conductivity (EC) maps from ECs measured in about 690 of those wells for the years 2009 and 2010.  All off the maps help inform managers of potential drainage problems in their areas due to encroachment of shallow groundwater.  The number of agencies participating is a reflection of the significance of drainage problems in the San Joaquin Valley and the potential impacts.

This report focuses on five years of data collection and compilation for the calendar years 2006 thought 2010, with a special focus on historical arsenic, boron, and selenium.  In addition, pesticide and nutrient data have been added to this report for your use..