The Central Sacramento Valley Study Unit was sampled between 6/29/2006 and 9/13/2006; 108 wells were sampled.
The study unit consists of 2 study areas:
• West Sacramento River Basin (consists of Colusa and Corning Basins)
• East Sacramento River Basin (consists of Vina, West and East Butte, West and East Sutter, and North and South Yuba Basins)
The study unit is within the Butte, Colusa, Glenn, Tehama Sutter, Yolo, and Yuba counties.