UPDATE (Aug. 5) -- Lake Mead National Recreation Area announced on Wednesday that water quality levels at some areas of Lake Mohave have returned to normal.
According to a news release, the water quality levels at Arizona's Princess Cove on Lake Mohave has returned to normal. As a result, the swim advisory at this location has been lifted.
However, the North Arizona Telephone Cove swim advisory remains in place on Lake Mohave. Officials said that bacterial levels are declining, but additional monitoring is required for pubic health and safety.
There are currently no other swim advisories on Lake Mead or Lake Mohave, the release said.
Original story continues below.
LAS VEGAS (FOX5) -- The Lake Mead National Recreation Area is warning visitors to avoid swimming and contact with water at Princess Cove and North Arizona Telephone Cove on Lake Mohave, until further notice.
The waters exceeded local, state and National Park Service water quality standards for recreational activity, the National Park Service announced on Thursday afternoon. Biologists are re-sampling the water daily, and once levels return to acceptable levels, the advisory will be lifted.
Increases in bacterial levels like this are often caused when people dump RV or vessel sewage tanks in the water, the park service said.
Free dump stations are available at all park campgrounds. If a visitor sees or suspects illegal dumping, they are advised to call 9-1-1 immediately.
For more information on fecal coliform, visit the Environmental Protection Agency website at https://archive.epa.gov/water/archive/web/html/vms511.html.
For more information on enterococci, visit the Environmental Protection Agency website at https://www.epa.gov/national-aquatic-resource-surveys/indicators-enterococci