Some very good ideas from Water Deeply, though nothing beats a big dam for addressing all three water storage benefits—flood control, storage, hydroelectric power.
One of the persistent myths about California water policy is that we haven’t built new water storage facilities since the 1970s. But a careful examination reveals that water agencies have built hundreds of storage projects over the past four decades. Those projects reflect a wide range of new approaches to meet 21st century water needs. Recognizing this progress can help develop more sustainable water policies.
Three factors explain why storage is central to meeting California’s water needs. Our state is remarkably dry for half of the year, with the greatest water demand coming during the dry summer. Roughly 75 percent of water demand is in the south, while 70 percent of the precipitation is in the north. Finally, year-to-year, California’s climate is among the most variable in the world. Conservation and other strategies can reduce reliance on storage, but it will remain a key water management tool.
Prior to 1978, the dominant storage strategy was a simple one: find a river and build a dam. In 1923, the first large dam in the state was completed, forming Hetch Hetchy Reservoir. And in 1978, construction was completed on New Melones Dam, the last large water supply dam on a major California river. During the intervening 55 years, water agencies built 800 dams – more than a dam a month for half a century.
However, after 1978, water agencies changed direction, discovering creative ways to store water. These new strategies differ dramatically from the approach used from 1923 to 1978.
Instead of focusing on damming rivers, new strategies include off-stream reservoirs and groundwater storage – often at a fraction of the cost. Water managers realized that improved management can provide more storage without expensive new infrastructure. For example, water managers have built, or are planning, new storage by restoring wet mountain meadows, expanding floodplains and by jointly operating reservoirs and groundwater aquifers.
Instead of relying on rivers as the sole source of water for storage, some new projects tap into nontraditional sources, such as urban stormwater and recycled water. The amount of new water available is impressive. The State Water Resources Control Board has a goal of developing 3 million acre-feet of supply from stormwater and recycled water, compared with 2002 levels. That’s far more than the average deliveries of the State Water Project. These new supplies show up in surprising places. For example, the largest untapped “river” in Southern California is a sewage treatment facility – the Los Angeles Hyperion Water Reclamation Plant – with its outfall nearly equal to the Santa Ana River flow, the biggest natural Southern California river.
Traditional storage projects maximize average water deliveries. In recent decades, however, conservation has flattened the growth of urban demand. As a result, water managers have focused more on projects to ensure reliable dry year supplies.
Instead of large reservoirs hundreds of miles from cities and farms, new storage projects are decentralized and closer to demand centers, with a wide range of benefits.
Finally, traditional dams have severely harmed the Sacramento-San Joaquin Delta, rivers, fish and wildlife, and the fishing economy. Today, water managers have found ways to store water without environmental damage and, in some cases, with significant fish and wildlife benefits.
Two proposed storage projects illustrate many of these new strategies.
The Contra Costa Water District is planning to expand its Los Vaqueros Reservoir. Water from the project would largely be dedicated to two uses. First, it would provide drought year supplies to help Bay Area communities – potentially including the East Bay, Silicon Valley and San Francisco – to better withstand the droughts that may become more severe and frequent as the impacts of climate change grow. By building storage close to these cities, water managers are increasing local control, reducing uncertainty and better ensuring that dry year supplies will be available when the next drought comes.
Second, Contra Costa Water District proposes to dedicate up to half of the project’s water – if funded by the California Water Commission – to managed wetlands south of the Delta. This would represent the largest single block of new water for California waterbird habitats since a federal law was passed a quarter century ago to improve wetland supplies. This project would reverse the impacts of past traditional dams on the most important wintering waterfowl habitat in the West.
In another example, a Southern California project shows more characteristics of new storage strategies. The Los Angeles Department of Water and Power plans to clean up contaminated San Fernando Valley groundwater to allow the department to store recycled water, urban stormwater and Sacramento-San Joaquin Delta water in wet years. Thus, instead of one water source, like traditional dams, this project would have three sources. Because recycled water is relatively unaffected by drought, this new storage can be more reliable during dry years. Recycled water projects were not previously considered to be storage projects – yet they clearly are.
Retrieved January 30, 2018 from https://www.newsdeeply.com/water/community/2018/01/25/new-water-storage-strategies-serve-californias-21st-century-needs