When a rural property owner installs a well system down gradient or too close to a residential septic system, he or she can increase the potential for the well pump to draw septic leachate into water ultimately stored and used within a residence. This unfortunate situation can be expensive to remedy and can have adverse health effects on local residential consumers using the system for drinking water.
Errors similar to the one just described should not be repeated on a grand scale. Unfortunately, proponents of the Woodland-Davis surface water project appear to have made such an error by locating the surface water intake structure for the project on the Sacramento River east of Woodland. This structure is south of a major agricultural discharge at Knights Landing. There, the Glenn-Colusa Irrigation District discharges irrigation return water containing rice herbicide residues and other potentially carcinogenic substances through an outfall directly into the Sacramento River.
During the summer irrigation season, the irrigation return water discharged through the Glenn-Colusa outfall is at a maximum. This maximum discharge coincides with the proposed maximum pumping of Sacramento River water down channel from the outfall by the Woodland-Davis project to meet anticipated summer urban water demand within the two cities.
As a result, there appears to be a conflict between the permitted discharge of irrigation return water from the Glenn-Colusa Irrigation District into the Sacramento River at Knights landing, and the objective of the surface water project to access and treat surface water of unimpaired quality in an economical manner to meet summer urban needs.
The unfortunate placement of a surface water intake structure below a major, permitted agricultural discharge also can be expensive to remedy and can have adverse health effects on all consumers ultimately using the Woodland-Davis system as a source for drinking water. Be cautious in giving blanket approval to this flawed and expensive project!
I received my Ph.D. in aquatic ecology from UC Davis in 1978 and have worked on water quality monitoring and analysis issues for more than 30 years. I was chief of the Bay-Delta Monitoring and Analysis Section with the California Department of Water Resources for 16 years before my retirement.