Scotts Valley Water Supply: Climate change, not growth, is the larger threat

With several large housing projects on the horizon in Scotts Valley, including the Town Center project with a proposed 300 new units of housing, growth has become a hot issue in Scotts Valley, and has raised many questions at public meetings about adequate water supply.  
Last week, Piret Harmon, General Manager of the Scotts Valley Water District, in a presentation to the Santa Margarita Groundwater Agency (SMGWA), made it clear that water districts are not authorized, by state law, to determine the growth policies for the cities they serve. Water districts are only authorized to advise and stay in constant communication about water supply with decision makers in land use agencies, typically city planning departments and ultimately city councils, among others, who are responsible for planning and managing growth.
Meanwhile, a state-mandated “sustainability plan” for the Santa Margarita aquifer, from which Scotts Valley draws its water, is underway by SMGWA. This comprehensive plan needs to meet state standards and be completed before 2022, and is required to detail what policies and what projects will be necessary for the aquifer to achieve and maintain “sustainability” for the next 20 years, until 2040.
Harmon explained the recharge of the aquifer is much more dependent on variations in rainfall than the more certain variables of projected consumption. With the current efficiency of water use in new housing developments and the use of recycled water for landscaping, Harmon indicated that 100 new homes would increase the total consumption of water by only about one percent of current consumption.
But “drought is a totally different magnitude… It is very hard to estimate sustainable yield in the aquifer with wide fluctuations in rainfall,” Harmon said. 
In her presentation, assisted by statistical information on slides, Harmon made clear that data on historical consumption is not a reliable predictor of future demand, nor is rainfall “a reliable supply chain.” In the 20 years between 1975 and 1995 the population of Scotts Valley doubled, and demand for water tripled, Harmon explained. By the water district’s own admission, this is when the Santa Margarita aquifer was “over pumped,” and the modeling clearly shows a sharp, downward sloping trend of water storage in the aquifer.
Over the next 20 years, however, between 1995 and 2015, with a much slower population growth, only a 22 percent increase, combined with several factors- including the decommissioning of quarry operations, advances in water saving technology, especially low-flow toilets, and strong consumer conservation during the recent drought, water consumption actually decreased by 26 percent over the last 20 years.
This allowed water storage in the aquifer to sustain itself at a certain level, although at a much lower level than was measured in 1985. The Scotts Valley Water District and SMGWA estimate the water level in the aquifer dropped by as much as 200 feet between the mid-1980’s and 2004, when depletion stopped and water storage in the aquifer more or less leveled off.    
One of the key discussions at the SMGWA meeting was at what level the aquifer should be restored or “retro-actively” recharged – and what impact such a “recharge policy” would have on land-use decisions. John Ricker, the Santa Cruz County’s Water Resources Division Director, indicated that any restoration of previous levels of the aquifer could be locally determined, and discussed by the SMGWA board, but the state requirement is that storage levels are no worse than conditions on January 1, 2015. 
Currently, according to Harmon, the 2015 Urban Water Management Plan, which water districts are required to update every five years, assures land use authorities there is enough water supply and infrastructure for an additional 1,500 people, or about 500 homes in Scotts Valley.
Ultimately, Scotts Valley’s General Plan, which is more than 20 years old and is currently getting updated,  suggests the city can accommodate up to a total of about 3,000 more people, or roughly 1,000 more new homes, before the city is completely “built-out” to its maximum capacity under current zoning. But these growth projections from land-use agencies have raised critical questions by the public, both about the quality of life in Scotts Valley generally and the level of water in the Santa Margarita aquifer that should be sustained.  
In response to the discussion of limiting growth, Bruce McPherson, Fifth District County Supervisor who also serves as a director on the SMGWA board commented, “I haven’t seen this strong a plea for more housing in Santa Cruz County in two generations.”   
 “The big uncertainty is climate change,” Harmon said. Harmon emphasized that urban growth related increases in consumption were relatively minor compared to serious droughts. “Do we need to plan for a five-year drought like we had in the 70’s, or a three year drought like the 90’s, or a 20-year drought like they had in Australia,” Harmon asked attendees of the SMGWA meeting.
SMGWA is complicated and the more we can communicate it in a straightforward and uniform manner, the more successful we’ll be in having a plan that is approved by the State and accepted by all stakeholders,  Harmon wrote in an email to the Press Banner.