The ever-saltier Salton Sea could be saved by a simple one word solution -- algae. At least that's what a trio of scientists from the Scripps Institution of Oceanography in San Diego believe.
Their idea -- to have farmers in the Imperial Valley grow algae, which uses less water than traditional feed crops like alfalfa -- would allow more water to flow into the Sea, hopefully stabilizing its salinity. As part of a 2003 water transfer between the Imperial Irrigation District and San Diego County, the state is legally obligated to "restore" the sea. The state's proposed plan to do so involves construction of a large horseshoe dam and wetlands with an estimated capital cost of $8.9 billion over 75 years plus annual operating expenses of $153 million.
The Scripps scientists think algae is a cheaper alternative.
"By substituting some of the crops that are more water intensive for algae, that water can be sent into the Salton Sea and the collapse of the habitat from increased salinity might be thwarted," said Neal Driscoll, professor of geology at Scripps Institution of Oceanography.
The Salton Sea is California's largest inland lake. It's 15 miles by 35 miles. Like Death Valley, the Sea is below sea level -- some 226 feet -- and is fed by the New, Whitewater and Alamo rivers as well as run-off from neighboring farmlands.
"In the coming decades, a transfer of Colorado River water from Imperial Valley to San Diego County will reduce the amount of agricultural runoff that currently flows into the Sea," notes a 2008 report on the Sea's status by the Legislative Analyst's Office.
"Primarily due to this change in water use, the Sea will begin to dry up—impairing air quality, reducing the availability of wildlife habitat, and increasing the salinity of the remaining Sea, thereby killing off most aquatic life."
Created by accident in 1905 when Colorado River floodwaters breached an irrigation canal, the lake now supports 270 species of birds -- some permanent residents, others migratory visitors -- and several species of fish. The major problem with the Sea is that it lives up to its name. Water flows in but doesn't leave. As the water evaporates, salt deposits remain. In 2008, the Sea's salt content was 44 parts per thousand compared to the Pacific Ocean's 35 parts per thousand. The most recent measurements of the Salton Sea show it at 51 parts per thousand and climbing, according to Driscoll.
Salinity will increase quicker once the 2003 water transfer between Imperial and San Diego occurs. The deal remains in litigation. But when the transfer happens, inflow to the Sea will fall to roughly 900,000 acre feet annually -- 400,000 acre feet less than the 1.3 million acre feet that evaporates each year. Less inflows speeds the climb in salinity. And, Driscoll says, less water in the lake will increase the intensity of the next earthquake along the southern San Andreas Fault which is expected to occur within the next 30 years.
There are other issues with the Sea as well. The agricultural runoff that maintains the Sea contains fertilizer. The municipal wastewater that flows into the Sea has phosphates. Both are nutrients that stimulate plant growth. In the Sea's case, that's algae -- not the good kind Driscoll and his colleagues envision. When the Sea's green algae blossoms and dies, a chemical reaction sucks the oxygen from the water, causing the death of large numbers of fish, the most prevalent species being tilapia. Blooms of brown algae, on the other hand, appear to increase the oxygen.
The state's mitigation plan for the lake is largely triage. Driscoll and his colleagues note that despite its expense, the proposal doesn't solve all the lake's problems, particularly water quality, and could exacerbate others such as air quality by allowing a large portion of the current lake to dry up. Central to the $8.9 billion plan, for which no money has yet been appropriated and whose price tag has likely increased in the three years since it was developed, is a 52-mile horseshoe shaped dam that would create a marine sea from northern edge south along both the western and eastern shores. This would provide habitat for fish and recreation opportunities. Salty wetlands would be created at both the north and south ends of the lake. The center of the current lake would be largely "playa" -- dirt -- with machines built to try and reduce the pollution caused by swirling dust particles.
Any effort to restore or even maintain the Salton Sea has been placed on hold due to the state's budget woes. Driscoll and his fellow scientists predict cash is one reason why the state is likely to rethink its Salton Sea strategy. And that invariably brings them back to algae.
In a presentation to attendees of the California Independent Voter Project conference in Hawaii, Driscoll and Greg Mitchell, a Scripps biologist, attempted to make the case for replacing some of the Imperial Valley's water instensive crops with algae. Seventy percent of Imperial Valley's irrigated water is used for soy and alfalfa, animal feed. Algae makes equally nourishing feed, Mitchell said. Among the other arguments in favor were that algae uses two to three times less water, and the water it does use can be what scientists call degraded. The photosynthetic process also eats up phosphates and some of the other nutrients flowing into the Sea. And Imperial Valley has the right conditions.
"The Imperial Valley is the ideal location for a massive scale-up of algae," Mitchell told the conference's attendees. "The sunlight is good. the temperature is good."
Additionally, algae can be harvested to create biofuels. Overall, Driscoll and Mitchell say, growing mroe algae in Imperial Valley uses less water, improves the quality of the water it does use, and in turn helps keep inflows to the Sea at current levels, potentially halting the increase in salinity. Driscoll urged state lawmakers at the conference to create financial incentives such as tax credits or creation of an enterprise zone to spur higher levels of commercial algae growing in the Imperial Valley.
"You're going to see the state reopen this issue because in these economic times $8.9 billion is an awful lot of money the state doesn't have," said Driscoll. "Particularly when there's a greener, better yielding return for the Salton Sea without such a huge monetary investment."
