Harsh Habitat: The Endangered Desert Pupfish

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Several previous posts have discussed the ecological importance of the Salton Sea, particularly its effect on migratory birds. However, the Salton Sea is also home to a much less obvious endangered species, the tiny desert pupfish. Desert pupfish, which are less than 3” long fully grown, are an unusual species due to their incredible tolerance for extreme water conditions. The desert pupfish can survive at salinities of up to 70 g/L—more than double the salt concentration of seawater.[1] This has historically allowed the desert pupfish to live in saline lakes, rivers, and marshes throughout the deserts of California, Arizona, Colorado, Nevada, and Mexico.

Desert Pupfish, Cyprinodon macularius, John Rinne

Water Rights and the Salton Sea

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For a long time now, the Salton Sea has been close to the bottom of the priority list when it comes to water allocations and this has placed the Sea in a very tight spot. We have discussed extensively the consequences of allowing the Sea to dry and the temporary solutions outlined under the QSA. It has been recognized by the many stakeholders that the Salton Sea needs help but not much has been done. The Salton Sea needs a long-term solution that could give it hope for a sustainable future. Given the current conditions of the Salton Sea and the implications of allowing it to dry, perhaps an ambitious solution would be to incorporate the Salton Sea into future revisions of regional water laws.

Sink or Swim (or Float): Water Quality and Salinity

You are going to the Salton Sea this weekend. It’s the desert; it’s going to be really hot, so you want to know if you will be able to cool off in the water. Considering the massive fish die-offs and the occasional nasty odor for which the Salton Sea is notorious, you might be concerned about the safety of swimming in the water. You probably want to know the answer to two questions:

First question: Can you swim in the Salton Sea?

Answer: Of course you can! It’s full of water, it reaches a depth of 50 ft., and there are plenty of crowd-free beaches. Not only can you swim in the sea, but you can also float really well. There are approximately 55 grams of salt per liter of water (g L^-1). This salinity is higher than the ocean, which has ~33 g L^-1; thus the water is more dense and, with no waves, the relaxation potential is greater [1].

Second question: Should you swim in the Salton Sea?

A Thirsty Sea

Located in an extremely arid region, the Salton Sea is subject to high temperatures and low precipitation. Extreme evaporation alone causes the water level at the Sea to decrease 5.4 ft. every year [1]. Historically, the majority of the water inflows at the Sea have been from diversions of the Colorado River, inputs from Mexico, and agricultural discharges from Imperial, Coachella, and Mexicali Valleys. Without these vital inflows, the depth of the Sea will quickly decrease causing release of contaminants currently present at the bottom of the lake and increase in salinity to even higher levels. The current salinity at the Sea is about 54 g/L which is much higher than the salinity in the ocean which is on average 35 g/L. This high level of salinity will affect the habitability for fish at the lake where only tilapia species have been able to survive despite massive die offs.