2002 Water Supply Feasibility Study
Davis Water System
The Davis service area includes the City of Davis, El Macero (located south of Interstate 80), and additional areas to the north, south, east and west of the City. The area has a population of approximately 66,000. Figure A (Link to Figure A) shows the service areas of Davis, UC Davis, and West Sacramento.
Existing Facilities
Water is currently supplied by 22 active wells located throughout Davis as shown on Figure B. (Link to Figure B) Most Davis wells are completed in the intermediate aquifer system at a depth of approximately 300 to 600 feet. Newer wells (28, 29, and 30) are completed in the deep aquifer to depths ranging from 1,400 to 1,800 feet. Distribution pipelines and storage reservoirs are also shown on Figure B.
Surface Water Entitlements
In October 1994, the Yolo County Flood Control and Water Conservation District (District) filed a water rights application for appropriation of surface water from the Sacramento River on the behalf of the Davis, UC Davis, and other entities in Yolo County. Davis is pursuing a right to divert up to 20,000 acre-feet per year of water from the Sacramento River, and is taking appropriate actions to keep future options open.
Water Quality
Water from the intermediate depth wells is generally very hard (high calcium level) and high in total dissolved solids. Nitrate levels are close to the drinking water limit in several wells and required abandonment of well 16. Boron levels are high enough to adversely affect sensitive plants, but not high enough to adversely affect human health. Arsenic and hexavalent chromium levels are relatively low, but may exceed future drinking water limits. Selenium concentrations are sufficiently high to cause problems at the City’s wastewater treatment plant, but are below drinking water limits.
Water from the deep aquifer has moderate levels of hardness and total dissolved solids. Available information indicates that boron, hexavalent chromium, and selenium are not problematic constituents. Arsenic levels do not exceed current drinking water limits, but may exceed future limits for this constituent.
Figure C and Figure D compare water quality of various water supply sources. In general, intermediate depth wells provide the lowest water quality for most parameters, and treated surface water from the Sacramento River is the highest water quality. Deep aquifer water quality generally lies between these two sources and represents an opportunity to improve system water quality in the near future.
