MILWAUKEE, Wis. (WTAQ) - Hexavalent chromium was made famous in the motion picture, "Erin Brokovich."

Years later, the Milwaukee Health Department and Milwaukee Water Works are explaining why its presence in the city's public water system doesn't offer an imminent health threat.

The chemical is considered to be a probable carcinogen. Laboratory tests have found it at various points in the city water system.

The tests were conducted after an environmental group included Milwaukee and Madison on a list of cities where levels of the chemical were higher than standards being considered for water supplies in California.

One city health official says he see no evidence that Milwaukee drinking water is unsafe, but he adds that the city is taking the situation "very seriously."