Contra Costa County, CA Water Table Trend
Contra Costa County, CA: the closest actual trend
The closest qualifying well to Contra Costa County is 19 miles away in Alameda County, CA, where the trend runs holding roughly steady.
Contra Costa County itself has no monitoring well with enough history to call its own trend, so treat this as a regional estimate, not Contra Costa County's own number. If you own a well here, comparing your own depth log against this regional figure is worth doing before assuming either way. See Alameda County, CA's full page. See the no-data guide for why a county this close to a qualifying well still doesn't get its own number.
Contra Costa County, California in brief
About 1,172,607 people live across Contra Costa County's 717 square miles, in California. USGS's National Groundwater Monitoring Network covers 1,449 of 3,222 US counties (45%) today; Contra Costa County isn't one of them yet, see the methodology guide for the exact qualifying bar.