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?

The answer to that question is less straightforward, but after we discuss the reason for the fish kills and the odor you can decide for yourself.

The Sea was created in 1905 with water from the Colorado River, and since this date it has been maintained largely by agricultural drainage. The saltiness of the Salton Sea is not from the Colorado River, which has a salinity of 0.73 g L-1, but from the farmlands, bringing in 3 g L-1 of salt. Farmers in this area are under scrutiny for using so much water, but to make anything grow in the Salton Trough the salt needs to be flushed from the fields. The salinity of the Sea is projected to triple in the coming years as the influx of water decreases due to the Quantification Settlement Agreement (QSA) such that the rate of evaporation will exceed the rate of replenishment [2].

In addition to bringing in the salt and 90% of the water volume, the agricultural drainage carries pesticides, nitrogen, phosphorus, selenium, and other trace elements. The high concentration of phosphorus and nitrogen feed algae. With more food available the algae increase in number and use up the dissolved oxygen in the water. As the algae die, as part of their natural life cycle, bacteria consume the dead algae and produce hydrogen sulfide (H2S) as a byproduct, thus causing that noxious sulfur smell. A combination of the high salinity and decreased availability of oxygen has been the primary cause of the fish kills that have been occurring since the 1970s [3].

On a normal day the levels of hydrogen sulfide (H2S) emanating from the Salton Sea are not harmful to humans, and since our olfactory systems are extremely sensitive to H2S, we act as our own sensors for whether the air is safe to breathe or not. Humans can smell H2S levels down to a few parts per billion (ppb), but California’s standard for outdoor concentrations of H2S is 30 ppb [4]. Although unpleasant, it is generally not harmful to breathe low levels of H2S as long as the exposure occurs infrequently [5].

People do swim in the Salton Sea (evidence) [6]. The lack of oxygen and high salinity can be toxic to fish, but on an average day it is probably ok to take a quick dip in the water. There are times you should avoid swimming in the Salton Sea: when hydrogen sulfide levels are high, when the Sea is thick with green algae, or when the water is covered with dead fish. It probably should not be an activity you do regularly, but if you really need to cool off in the desert, the water is safe enough to swim in. However, to avoid becoming a human saltlick, I would also advise against swimming in the Sea without a shower nearby.

 Written by Melissa Morgan

[1] Cohen, M. 2014. Hazard’s Toll: The Cost of Inaction at the Salton Sea. Pacific Institute. <>.

[2] Cohen, M.; Hyun, K. 2006. “Hazard: The Future of the Salton Sea With No Restoration Project.” Pacific Institute. <>.

[3] Cohen et al. 1999. Haven or Hazard: The Ecology and Future of the Salton Sea. Pacific Institute. <>.

[4] (South Coast AQMD 2014) ( 2015).” <>.

[5] “Hydrogen Sulfide.” 2015. Wikipedia, the Free Encyclopedia. <>.

[6] Swimming in Salton Sea. 2014. <>.