Creation of the Sea

• In the spring of 1905, a diversion of the Colorado river south of the U.S.-Mexico border failed during flood conditions.

• For almost two years, the entire flow of the Colorado river flowed into the Salton Sink, filling it to -59.4 m, with a surface area of 1347 km².

• The lake level decreased, reaching an all-time low of -76.2 m in the early 1920's.

• Since then, agricultural activity has expanded in the valley.

• In 1928, an Executive Order designed lands within the Salton Basin below -67.05 as storage for wastes and seepage water from irrigated lands in the Imperial valley.

• Since then, the use of the Salton Sea as a repository for agricultural wastewater has led to increased inflows to the lake.

• In the past 70 years, the lake level has increased gradually to its present (1998) level of -69.2 m.

• In 1907, after formation, the salinity of the Salton Sea was 3.5 ppt (3500 ppm).

• Salinity increased afterwards, reaching 37.6 ppt (37600 ppm) in 1923.

• Salinity now exceeds 44 ppt (44000 ppm).

• In the past 15 years, the rate of increase of salinity has been 0.43 ppt yr^-1.

• At this rate, it is expected that the lake will become totally unfit for fisheries biota by the year 2010.

• The restoration must accomplish the following objectives:
  
  
  • Reduce the salinity to that of the oceans (34500 ppm) to preserve the lake's biological and recreational resources.

  • Decrease the lake level to the more manageable range of -70.1 to -71.6 m to control flooding and ensure that the lake level remains beyond the legal permissible limit (not higher than -67.05 m).

• The recognition that the Salton Sea is in ecological trouble is not new.

• Initially, the Salton Sea supported a community of freshwater fishes which came with the Colorado river floodwater.

• As salinity increased through the years, the original freshwater fish disappeared.

• Between 1929 and 1956, the California Department of Fish and Game made numerous transplants of both fish and invertebrates with the aim of developing a sport fisheries in the sea.

• Of the numerous species intentionally transplanted, only the pileworm, mudsucker, and three sport fish (corvina, sargo, and bairdiella) survived.

• No spawning occurred at salinities of 45 to 50 ppt.

• Most game fish will disappear at salinities above 50 ppt.

• Salton Sea is in the flyway of numerous migrating and wintering bird species, particularly waterbirds.

• The latter represent the higher trophic levels of food webs in the Salton Sea and surrounding areas.

• Irrigation is needed to support intensive agriculture in the Imperial and Coachella valleys.

• The agricultural wastewater is discharged into the Salton Sea through the drainage network.

• Anthropogenic inflows account for 96.7% of inflows to the sea.

• The Salton basin is endorheic, with three major rivers: the Alamo, New, and Whitewater.

• The Alamo and New drain the Imperial and Mexicali valleys to the south.

• The Whitewater drains the Coachella valley to the north.

  

• Together, these streams account for 85% of the inflows.

• Sodium (Na⁺), chloride (Cl^-) and sulfate (SO₄^-) ions constitute about 93% of the total salinity.

• Water evaporates and leaves behind the salt ions.

• The salinity of Colorado river water has been measured at 0.787 ppt (787 ppm).

• As the imported water flows through the irrigation system, the salinity increases due to the following reasons:
  
  
  • Leaching of the salts brought with the irrigation water (imported salt)

  • Leaching of salts due to excessive application of fertilizers (anthropogenic salt)

  • Leaching of salts already available in the soil profile (old or fossil salt).

  • Leaching of salts produced by the normal weathering of soil minerals, exacerbated by the irrigation process (new or current salt)

• Over the past several decades, expanding agricultural activities has led to increased wastewater inflows to the Salton Sea.

  

• The gradual rise in lake level has led to local flooding.

• In the past 40 years, the lake level has risen by 2.44 m to the present -69.2 m.

• If this rate is linearly extrapolated, the lake may reach its legal limit in about 35 years.

• Recent data indicate that the lake may be close to achieving a hydrologic equilibrium (inflows equal to evaporation).

• Agriculture is important to the region's economic prosperity, and that of California and the United States.

• There are 186,000 ha of irrigated land in the Imperial valley, and 24,200 in the Coachella valley.

• MOREOVER, THE REGION IS A MAJOR PRODUCER OF WINTER CROPS IN THE UNITED STATES.

• The agricultural production of the two valleys amounts to 1.3 billion dollars.

• The lake cannot exist without inflows from agricultural drainage, which provide the much needed water.

• These inflows are loaded with dissolved ions, which are degrading the lake and impairing its other uses.

• Issue of geology, physics, chemistry, biology, ecology, agriculture, and economics are intertwined.

• Salinity must be reduce to ocean level.

• Salts have to be removed at the rate of 0.85 ppt yr^-1

• The salts to be removed amount to 8.16 million metric tons yr^-1.

• After the 30-yr restoration period, the salts to be removed are about half of this amount.

• Restoration is energy intensive.

• Solar and geothermal energy is already available.

• More than 50 proposals have been advanced to restore the sea.

• The 1998 USBR study narrowed the list to five types of diked impoundment.

• The diked impoundment would concentrate the salts in an enclosed portion of the lake, creating an hypersaline lake.

• Water is expected to flow by gravity to the impoundment, eventually decreasing the salinity of the lake to ocean level.

• This alternative will degrade 1/7 of the lake to restore the health of the remaining 6/7.

• As the salinity of the diked impoundment increases, its evaporation rate will decrease.

• Research has shown conclusively that evaporation rates vary with salinity and temperature.

• For example, a brine with 400 ppt will evaporate at rates varying from 5 to 26% of that of freshwater.

• The reduced evaporation will effectively raise water levels.

• The proposal (approved) to sell 200,000 ac-ft annually to San Diego will result in a corresponding decrease in lake inflows.

• This assures that the dike impoundment solution will not work.

• A proposal to restore the Salton Sea using solar still distillation is presented.

• The products of distillation are water of high purity and a highly concentrated brine.

• Distillating 75% of the water will concentrate the 47% brine to 188 ppt, with a specific gravity of 1.15.

• The water lost in the distillation process (25%) amounts to 3% of the lake inflow.

• Evaporation ponds will be needed to reduce the brine to exportable salt.

• The extracted salts can be transported out of the region for ultimate disposal in the high seas.

• The distilled water may be returned directly to the sea.

• If the lake is increasing, a fraction of the distilled water may be commercialized to control lake level.

• Solar distillation has the following advantages:
  
  
  • It helps reduce the lake level to a more manageable range.

  • It can be operated for unlimited periods.

  • It does not degrade lake surface area.

• Solar distillation is a feasible alternative to restore the Salton Sea.

• Solar distillation has the following advantages:
  
  
  • It is environmentally friendly.

  • It is sustainable, because it can be operated for unlimited periods.

  • It is holistic because it does not degrade surface area.

OUTLOOK

• The diked impoundment alternative has been abandoned by the Salton Sea Authority as of 2001.

• Monies have been made available recently (October 2002) by the state to continue to "study" the problem.

• More monies (at least 1 billion) will be required to clean the Salton Sea.

• Who will pay? IVC? The state of California? The federal government?

• The almost sure transfer of 200,000 ac-ft of water annually to San Diego County will have to be accounted for in any restoration effort or project.

• Current agreements postpone the problem for 15 years, buying time so that more studies and knowledge become available.