Report to the California State Legislature Joint Legislative Budget Committee on Reduction of Agricultural Pollution Runoff into the Sacramento-San Joaquin Delta

This report has been prepared pursuant to the requirements of the Supplemental Report to the 2008 Budget Act:

“On or before March 30, 2009, State Water Resources Control Board (State Water Board) shall submit a report to the Joint Legislative Budget Committee and to the relevant policy committees that details: (a) the precise actions the State Water Board would have to undertake to obtain a 30 percent reduction to agricultural pollution runoff in to the Sacramento-San Joaquin Delta [Delta] and its tributary watersheds by 2012, (b) the estimated costs of those actions, and (c) which of those actions can be completed administratively and which would require legislation to implement.”

The Central Valley Regional Water Quality Control Board, (Central Valley Regional Water Board) staff has determined that replacing irrigation practices that produce return flow is the only method of ensuring a 30 percent reduction in agricultural pollution runoff to the Delta by 2012. The program would be focused within the Delta and San Joaquin River watershed and apply to surface return flow (tailwater). Tailwater can convey contaminants applied to or on the land surface, such as pesticides, sediment, fertilizer, and manure. Tile water (subsurface drainage pumped to surface waters) contains naturally occurring minerals found in ground water, and may contain contaminants leached into the ground water due to application on the land surface. However, tile water is not the focus of this control strategy, since it would take longer to implement the required control technologies.

Irrigation return flow is the focus of this effort, since it is more amenable to control (versus storm water runoff) and over 60 percent of the exceedances of water quality objectives we have identified occur during the irrigation season.1 A target of converting 50 percent of the irrigated acres that produce runoff to more efficient irrigation practices that produce no runoff is recommended. A 50 percent conversion target is recommended, since there are other pathways for agricultural pollutants to reach the Delta through surface waters (e.g., pesticide drift, tile water drainage), so a larger percentage reduction in irrigation runoff would be needed to ensure that the overall 30 percent pollution reduction goal is achieved.
The estimated cost to the agricultural community to implement the required management practices is $250 million – $450 million in capital cost, assuming half of the one million acres of agricultural land requiring improved irrigation management systems would be targeted to meet the 2012 timeframe. Additional Central Valley Regional Water Board staff resources of up to 10 PY would be required to ensure the required practices are implemented.