MADISON, Wis. -- Wisconsin outdoor experts said the recent hot weather has caused water-related concerns on some lakes and rivers.

Officials with the state Department of Natural Resources said there have been outbreaks of blue-green algae on some lakes in southern Wisconsin.

DNR officials said the algae is unsightly and smelly, can reduce oxygen levels in lakes and sometimes produces toxins. People and their pets should avoid those waters.

The DNR also said an outbreak of a naturally occurring bacteria called columnaris has caused some fish kills in northern lakes but it does not pose a threat to people or pets.

The bacteria generally doesn't cause long-term damage to the fishery, official said.