Frequently Asked Questions

This page has been adapted from the Salton Sea Action Committee.
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Where is the Salton Sea?

H​ow was the Salton Sea formed?

The Salton Sea, previously called the Salton Sink, was filled and dried up many times over the millennia. In fact the Sea has been wet 80% of the time over the last 15 million years. The Salton Sea is a terminal sea meaning that it has no outflow. The present filling of the Salton Sea occurred in 1905-1906 when the Colorado River flooded into the Salton Sink due to extreme flooding that year. Floodwaters broke through the headworks of an irrigation canal to the Imperial Valley. Subsequent to that event in 1905 the Sea’s level has been maintained at roughly its present elevation of -232 feet by agricultural drainage and tail water from the Imperial and Coachella Valleys.

H​ow much water evaporates from the Salton Sea annually?

​The total evaporation from the Salton Sea is approximately 1,300,000 acre feet of water per year. An acre foot of water is 326,000 gallons or approximately enough water to fill a football field to an elevation of 1 foot. The total volume of water in the Salton Sea is approximately 7.5 million acre feet.​

How big is the Salton Sea?​

​The Salton Sea contains approximately 7.5 million acre feet of water. It is 51 feet deep at its deepest point. The surface area of the Sea is approximately 376 square miles and it has about 110 miles of shoreline. The Sea is about 35 miles long and about 15 miles wide. It is the largest inland lake in the state of California.


 ​H​ow much salt goes into the Salton Sea every year?

4,000,000 tons of dissolved salts enter the Salton Sea every year. That is the equivalent of approximately 13, 500 train cars. The salt comes from agricultural drainage and tail water and the Colorado River itself. By the time Colorado River reaches southern California from the Rocky Mountains it contains about 2mg of salt per liter of water or 2 parts per thousand (PPT)

How Salty is the Salton Sea now and how salty will it be in the future​​​​​​​?

​The Salton Sea is approximately 53 parts per thousand (ppt) or 53 mg per liter. By comparison ocean water is approximately 35 ppt. The salinity of the Sea increases every year. As the Sea evaporates every year all of the salt delivered by drainage (13,500 train car loads) is left behind thereby increasing the salinity with each passing year. Although it is hard to predict salinity of the Sea is increasing more rapidly with every passing year and the rate of that increase will go up with every passing year. By comparison Mono Lake in the Owens Valley is 87 ppt. Mono Lake is extremely alive with Algae, brine shrimp and bugs and it supports many bird species but the lake itself does not support fish except in the tributary streams and their deltas.

How many fish and what kind of fish are in the Salton Sea?

Soon after the Salton Sea formed in 1905 many types of fish were stocked into the Sea for sport fishing purposes. In fact the Sea was a major sport fishing destination for nearly 60 years. At the beginning, the Sea was not very salty and would support many different types of fish. As the Sea reached salt levels similar to the ocean many ocean species were stocked into the sea as well. The salinity has unfortunally reached apoint where it is assumed that the only species of fish that presently inhabit the Sea are the algea eating tilapia, that were introduced into the All American canal for algae control en the 1960’s, and the endangered, indigeous pupfish. The tilapia have managed to adapt to thehigh salt levels however scientists believe that thesalinity is reaching a tipping point where even the tilapia will soon have a massive die-off. It was estimated in the 1990’s that the Sea was home to millions of tilapia.

How is the Sea filled today?

The Imperial Valley and to a lesser degree the Coachella Valley produce agricultural drainage water from hundreds of square miles of irrigate acreage. Most people do not realize that in addition to providing irrigation water to farming in both valleys the Bureau of Reclamation also constructed an intricate network of drain tiles to carry off leached water from farms. Because Colorado River water contains salts is necessary for farmers to over irrigate their land in order to remove those salts from the growth zone of plants. If the salts were not leached through the soil the farms would soon become unproductive. This leach ate, or tail water, as it is called is carried to the Salton Sea through the drainage system. When the All American Canal was built water was cheap and plentiful. The Canal itself was unlined as was most of the delivery network of smaller canals. These unlined canals also produce excess drainage to the Salton Sea. The combination of these drainage sources of water along with drainage from Mexico has been enough to keep the Sea reasonably maintained at roughly the 230 foot elevation. In other words in-flows have equaled evaporation. That is about to change dramatically.


Why is the Salton Sea shrinking?

Over the last 75 years water has become much more scarce and expensive do in part to urban development in the southwestern states that rely on Colorado River Water. The Colorado River only produces so much water and frankly we have reached its capacity. As a result farmers have become much more efficient in their use of water. Improved irrigation techniques and varieties of crops have dramatically reduces the amount of agricultural runoff. Additionally both the CVWD and IID have embarked on canal lining projects and other conservations methods that have reduced in-flows. As noted below Mexico is now treating and recycling much of the wastewater that flowed into the Sea through the New River. As a result of IID’s conservation methods and the Quantification Settlement Agreement water transfers to urban areas like San Diego will begin to significantly affect inflows starting in 2017. Significant acreage in the Imperial Valley has already been fallowed and is no longer providing irrigation runoff. Put simply, the in-flows no longer match the evaporation rate. It is estimated that in-flows into the Sea may drop to as little as 500,000 acre feet over the next two decades. The Salton Sea will need to be maintained on approximately one-third of its recent inflows.

Why is the Salton Sea an important ecological resource worth saving?

Over 400 species birds rely on the Salton Sea regional ecosystem. It is not only the Sea but the agriculture around the Sea is also important to certain species of birds. One is dependent on the other. Migratory bird species depend on the Salton Sea as a major stopover along the Pacific flyway. In fact it has the second most Avian bio-diverse region in the North America. Because of Wetland conversions in California due to urbanization and agricultural development 90% of the wetlands along the Pacific Flyway have been eliminated over the last century causing the Salton Sea to become an extremely important rest and feeding stopover for migratory bird populations. The Salton Sea is home to 80% of the western population of White Pelicans. Banded Salton Sea birds have been found from the Alaska to the bottom of South America. Birds have even been found and reported as far as Asia. The loss of the Salton Sea as a fishery and stopover for these bird populations will likely result in impacts to these species of staggering proportions. These birds rely on the Sea for rest and sustenance. This is a problem of international environmental significance. If the fish die from hyper-salinity the birds will die as well. We must find a way to increase and maintain the fishery and the wetlands to save these birds.

What caused the “Big Stink” in of September 2012? 

We have all smelled that nasty rotten egg odor emanating from a sewer, septic tank or port potty. That odor is often caused by hydrogen sulfide gas. Hydrogen Sulfide (H2S) is produced when organic material breaks down due to microbial activity in an environment lacking in oxygen. The enormous amount of life and organic matter in the Sea creates this gas at the deeper locations within the Sea but that gas is sequestered at these deeper locations. In the summer when severe wind events from the Gulf of California move northwesterly they can cause waves and turbulence in the Sea to a degree that brings the Hydrogen Sulfide Gas to the surface where it is then carried by the weather to population centers.  As the Sea continues to decline we can expect more big stinks.

Who owns the Salton Sea?

The land under the Salton Sea is owned almost entirely by three entities. The largest is the Federal Government. The Bureau of Reclamation and the Bureau of Land Management under the Department of the Interior own the lions share. Additionally a large amount of land under the Sea is owned by the Imperial Irrigation District. In the north, there is approximately 11,000 acres of tribal lands owned by the Torres Martinez Desert Cahuilla Indians and held in trust by the Bureau of Indian Affairs under the Department of the Interior. There are a few private holdings and the Coachella Valley Water District has a very small amount of acreage.

Aren’t the New and Alamo Rivers really polluted from Mexico?

Mexico, with U.S. assistance, has constructed a treatment plant on the New River in Mexicali that has decreased the pollution stream significantly coming from Mexico. Irrespective of the new treatment plant, as water flows down the New River 60 miles from Mexico natural sunlight, oxygenation and biological activity manages to treat the water such that by the time water reaches its delta at the Sea the water quality is equivalent to that of the nearby Alamo River which is almost entirely agricultural drainage or tail water.

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