Coastal Groundwater: Catch It Where and When You Can! – Guest Article
By Judy Corbett, PCL Board Member
Inadequate water supplies and floods are already major concerns in California. While many groups and individuals are working hard to address the problem, scientists tell us that climate change will pose even greater challenges in the future.
As the earth warms, so does the speed at which water evaporates, increasing the volume of water stored in the clouds. While models don’t make clear predictions about whether California will be wetter or drier in coming decades, on average, they tell us that we should expect more extremes, with less snowpack, longer and more frequent droughts, and more intense rainfall in the winter. We need to increase our efforts to catch and hold this precious water whenever and wherever we can!
California’s Central Valley is in a good position for storing water at a low cost because it sits on top of a system of deep aquifers, underground reservoirs that have been emptied in many regions due to droughts and over-pumping. Inspired in large part by the pioneering work of Aaron Fukuda at the Tulare Irrigation District, more flood control districts and property owners are beginning to direct runoff and flood waters to prime sites for recharge on their agricultural lands. The quest to identify the prime places where excess water can be quickly infiltrated and stored in aquifers is being informed through the use of electromagnetic imaging, a tool pioneered in part by Stanford University Professor Rosemary Knight.
In the more hilly and mountainous areas along the coast, underground storage capacity is limited to multiple smaller pockets under the surface. If overdrawn, these shallow aquifers are susceptible to saltwater intrusion. This presents a serious challenge to the central coast, where freshwater demand is met almost entirely by groundwater.
In Santa Cruz and Monterey counties, the water storage challenge is being tackled by a unique partnership between UC Santa Cruz, the Resource Conservation District of Santa Cruz County, and the Pajaro Valley Water Management Agency (PV Water). This group of forward-thinking individuals demonstrates the extraordinary benefit of motivated professionals coming together with landowners and growers to apply their complementary expertise and capabilities to avoid a future of inadequate water supplies and floods.
A decade ago, staff with the Resource Conservation District and the UC Santa Cruz Hydrogeology Group applied for and secured funds to create two regional GIS maps. One map would identify sites where the land surface and the catchment basins below make it suitable for stormwater recharge; the other would identify sites with enough stormwater runoff to justify directing water to an area. By combining the runoff map with the recharge suitability map, the Resource Conservation District and UCSC team identified key areas in Santa Cruz and Monterey counties with excellent potential for collecting and storing stormwater.
Parallel to these modeling and mapping efforts, regional community leaders championed aquifer recharge work as a solution to their saltwater intrusion and groundwater overdraft problems. Supported by the Resource Conservation District, the Community Water Dialogue emerged as a forum for local landowners and business leaders to work together to agree on solutions.
Resource Conservation Districts (RCDs) are special districts of the State of California with their own locally appointed or elected boards of directors. They implement projects on public and private lands, educate landowners and the public about resource conservation, and provide needed technical and financial assistance. RCD staff have close relationships and the trust of small property owners within their jurisdictions. They also have the financial resources to meet and converse with their constituents. They are the perfect partner to collaborate with landowners and universities to test and implement novel ideas and methods.
However, a third partner was also necessary to make this project viable. RCD staff work with individual property owners willing to volunteer their private property for an aquifer recharge project. Among other things, they assist property owners with funding the infrastructure that might be needed to make a recharge project happen. That can be challenging! This is where the Pajaro Valley Water Management Agency (PVWater) becomes a critical partner.
PV Water has adopted an idea first employed by electric utilities to reward private homeowners for producing excess electricity from their rooftop solar panels. The water version of this concept is called Recharge Net Metering. The RCD and UCSC team measures how much stormwater is collected and infiltrated within approved projects, and PVWater provides a rebate to the landowner’s water bill, using a formula based on the infiltration benefit measured.
UC researchers have demonstrated that water secured and stored through the use of Recharge Net Metering can be cost-competitive compared to other options being considered, while providing water quality and flood control benefits for both the land owners, the utility and the broader community. Recharge Net Metering appears to have an important statewide application for creating the needed economic incentive to maximize the acreage of land dedicated to groundwater recharge in California.
Judy Corbett is the co-developer of Village Homes, a model for sustainable development created in the late seventies. She went on to found the Local Government Commission. She served as its Executive Director — for 35 years, helping local elected officials implement forward-thinking transportation, land use, water, air quality, solid waste, public health, economic, and equity programs and policies in their communities. She has authored or co-authored three books on sustainable development and written or edited multiple guidebooks and fact sheets for local governments on sustainability issues. Her leadership toward creating the nationally-recognized Ahwahnee Principles foresaw the development of the Smart Growth movement.
Additional Resources and Further Reading
Partnership between the RCD, the water district, and UCSC. Demonstrates the meter used for net metering: https://www.rcdsantacruz.org/
Demonstration of the overlay of the two GIS maps that allow you to target the prime spots for recharge: https://www.rcdsantacruz.org/
Daniel Swain, who specializes in climate research: Climate chaos with climatologist Daniel Swain
Nature article on recharge net metering: https://www.nature.com/
Fisher, A. T., S. Lozano, S. Beganskas, E. Teo, K. Young, W. Weir, and R. Harmon (2017), Regional managed aquifer recharge and runoff analyses in Santa Cruz and northern Monterey Counties, California, 130 pp, California State Coastal Conservancy, Project 13-118, Santa Cruz, CA, Regional Managed Aquifer Recharge and Runoff Analyses in Santa Cruz and northern Monterey Counties, California.