California’s dependence on runoff from the Sierra snowpack, local runoff to reservoirs, and imported water from the Colorado River and Owens Valley to supply potable water to its population is well known. These sources can be significantly impacted by cycles of drought, environmental constraints, and regulatory restrictions. Even with the recent storms that have come through, this year’s drought is particularly pronounced, with the statewide snowpack at 34% of normal for early April according to the Department of Water Resources. Even with ongoing conservation efforts, increasing use of recycled water for irrigation, and the potential for indirect potable reuse on the horizon, water supply may not be sufficient to meet future demand. Local sources of potable water supplies are few, and often constrained by volume (potential for overdraft in the case of ground water supplies), environmental impacts, and judicial adjudications.
Seawater desalination offers the opportunity for a new, drought-proof source of potable water to augment agencies’ existing water portfolios. The use of desalination for municipal potable water supply in California has been gaining acceptance however development of these projects are an arduous process due to tight regulatory constraints, environmental concerns, and the relatively high cost per unit of water produced. However, advances in technology have resulted in a more efficient treatment process and desalination construction and operating costs are expected to eventually be in line with the wholesale cost of current water supplies for many agencies.
Desalination projects have many challenges, chief among them are the environmental concerns regarding potential impacts to fish and other aquatic life near plant water intakes and the potential damage to the environment caused by discharging the residual concentrate/brine produced during the desalination process into the ocean. Where possible new desalination plants that can be co-located with existing ocean-cooled power plants will minimize the need for new intake structures. Brine discharge may also be accomplished through existing outfall facilities. Of course given that coastal real estate is highly desirable in California, finding good candidate desalination facility sites is another major challenge. One of the largest facilities, currently under construction in San Diego County, is co-located with an existing power plant.
Although there are challenges, seawater desalination can improve the overall reliability of potable water supplies to meet California’s growing needs, especially in communities that import the majority of their potable water. It is possible to expand this new source of water supply while being good stewards of the environment. Desalination is a drought-proof, highly reliable and sustainable source of potable water that helps diversify drinking water sources, thereby improving the overall reliability of our water supply systems.
For more information on California’s water crisis, read ACEC California’s latest issues of Engineering and Surveying Business Review at the link below. You will find articles about the severe drought that continues to impact the entire state and ACEC California members offer potential solutions to our state’s water woes.