LakeMead.Mohave2BOULDER CITY, Nevada — The appearance of algae observed in Lake Mead and Lake Mohave has changed; therefore, National Park Service officials are now advising visitors to avoid swimming in areas where green algae is seen on the surface and where it appears suspended in the water.

It is not possible to predict the daily locations of algae, as it shifts hourly with wind and waves. However, there are no longer large mats of algae present in the lakes, as was seen in March. There may be isolated pockets of algae in coves, and the algae may appear on the surface or could appear as a green suspension in the water. Officials recommend avoiding both.

As a precaution, recreational visitors should follow a few safety tips where algae are present:

•Ensure pets do not drink or go into the water;
•avoid swimming, scuba diving, waterskiing or jetskiing in the area;
•do not touch residue on the shoreline;
•do not fill water tanks with water in the area;
•if contact occurs, rinse thoroughly with clean water;
•and as always, don’t drink untreated water straight from the lake.
Health issues related to contact with algae may range from rashes and skin irritations to gastrointestinal illness. Pets and small children are the most vulnerable. The park service has not received any reports of serious illness related to the presence of algae.

According to the Southern Nevada Water Authority, the algae do not pose a threat to Southern Nevada’s drinking water. The SNWA’s treatment plants utilize both ozone and chlorine, which represent the two most effective water treatment processes and it will prevent algae from entering the community’s water system.

While the likelihood of people being affected by contact with the algae is very low, federal, state, and local agencies in Southern Nevada continue to proactively monitor algae composition levels in both lakes.
Most areas of the lakes do not have accumulations of algae. Visitors and their pets can continue to enjoy the water where algae are not present.