(Photo by Jeff Shewan - CC BY 2.0)

Bartlett Lake in Rio Verde, Ariz.

If you’re planning to go fishing in Bartlett Lake, be careful what you eat. State officials are warning people about elevated mercury levels in some fish there.

Arizona hasn’t warned anglers about eating fish due to health concerns since 2011. For Bartlett Lake — north of Fountain Hills on the Verde River — this is the first time.

The two culprits: channel catfish and largemouth bass, some of the most common fish in Bartlett. Tissue samples collected there show elevated mercury levels ranging from 0.37 parts per million to 0.8 — all above the federal standards of 0.3 parts per million.

Randall Mathis is with the Arizona Department of Environmental Quality. He said they are not yet sure how the mercury is getting into Barlett, but generally in Arizona it is "due to a combination of both natural and man-made sources, historic mining can lead to increases in mercury.”

Adults can eat about 2 ounces per week without any health effects, according to the standards, but the threshold is lower for young children.

Mathis said they are currently testing lakes across the state for mercury and trying to determine the sources.