Intensive effort has been focused on closely coordinating operations of California’s major intrastate water projects (the Department’s State Water Project and the federal Central Valley Project) with requirements to manage Delta water quality, and to maintain targeted flow and temperature conditions for fish species listed pursuant to state and federal endangered species statutes. A real-time operations group of the involved state and federal water and regulatory agencies was established to carry out this coordination. The Department has been working with local agencies to compile groundwater level information and has prepared an initial report that contained some sobering findings – that groundwater levels have experienced all-time historical lows in most areas of the state and that groundwater levels in many areas of the San Joaquin Valley are more than 100 feet below previous historical lows. The Department has also been working closely with the Office of Emergency Services and the SWRCB’s drinking water program to assist them where needed in emergency response for communities with critical drinking water shortages (primarily small water systems in rural areas).
Drought is a normal and recurring part of the water cycle in California. Dry years happen periodically; sometimes dry conditions persist over multiple years, eventually resulting in sufficient impacts for these dry conditions to be termed a drought. Experience from our past significant droughts has identified gaps in information or tools needed for drought response, gaps that are again being highlighted in the current drought. These gaps also inform needs related to climate change adaptation at longer time scales, as much of the work associated with adaptation is about managing impacts of expected future water shortages.
Briefly, extensive material has been published about expected future impacts of anthropogenic climate change in California – increased water demands due to warmer temperatures, loss of Sierra Nevada and Cascades snowpack, and increased aridity in Southern California. In terms of timing of impacts, climate models generally show very pronounced impacts – such as loss of half or more of Sierra Nevada snowpack – by the end of the century, with notable impacts being observed by mid-century. Climate change impacts on water supplies and demands have also been quantified for the Colorado River Basin, an important source of imported water supply for Southern California. Some researchers have characterized impacts as the extremes (e.g., droughts) becoming more extreme, with a heightening of the natural variability historically observed in the climate system.