Like much of California, Santa Cruz County is projected to face intensifying weather swings from extreme dry conditions to extreme wet conditions. These weather swings will be experienced as longer, more frequent, and more intense droughts, that are punctuated by more extreme rain events. We have already begun to see this change with the 2022-23 Atmospheric River events, which dropped record amounts of rain on our county, but had been preceded by three years of drought conditions.
This change in rainfall patterns is likely to result in significant reductions in the amount of groundwater recharge. The reason for this is that all ground surfaces have a rate at which they can allow rain to infiltrate. As shown in this figure1, if the rate of rainfall exceeds the infiltration rate of a surface, then the excess water will become runoff. Historically, our county would experience smaller storms over much of the wet season, which allowed more of the total rainfall to infiltrate. With fewer and more intense storms, a greater percentage of rainfall becomes runoff instead of recharging groundwater. This means that years with normal or above average rainfall totals can still result in a below average amount of groundwater recharge. According to the Integrated Regional Water Management Plan, this change in rainfall patterns could reduce groundwater recharge up to 30% in some areas. Any reduction in recharge will create challenges for our county’s water resources, including over-drafted aquifers, stream depletion in the dry season, impaired water quality, and an overall degradation of riparian habitat.
Considerable work has been done by the County’s large water agencies and three Groundwater Sustainability Agencies to improve the study and management of local water resources. While Santa Cruz County has limited direct authority over water resources, the County continues to play a lead role in coordinating water management in our region. The emphasis in this coordinating effort is to build resiliency and preparedness. One area where the County will play a more direct role is in the support of domestic well users and small water systems, which have less ability to adapt to the coming challenges. Addressing this disparity was one of the primary goals of SB 552, which directs counties to provide a safety net for these vulnerable populations.
For more information about the current status of our water resources, please visit California Water Watch. This site offers the most current local water conditions down to your region and even your neighborhood.
- Figure is from the University of Arizona, College of Agricultural and Life Sciences