A new UC Riverside study finds that aquifers take longer to recover from severe droughts.

The effects of a drought on aquifers can take two years to be seen, and replenishing them takes three to 15 years. This is made worse by excessive pumping that lowers the groundwater level, which is already happening as the drought deepens in California.

This is “creating a downward spiral in which restoring the aquifer becomes harder and harder,” said study co-author Adam Schreiner-McGraw in a news release.