Woodbury is letting one city lake breathe so the fish can too.

City workers on Monday were scheduled to turn on an aeration system at Battle Creek Lake that will oxygenate the lake and help prevent "fish kills" that can be common in shallow bodies of water.

It also means that parts of the lake will be thin, and residents are asked to take care when using the lake, which is in the northwest part of Woodbury.

For the past several years the city has used the aeration system to help keep fish alive during winter, said Doug Peterson, Woodbury parks specialist. The city uses pumps to force oxygen through underwater tubes, which bubbles up to the surface "like an aquarium," he said. That opens up the lake's surface to allow sunlight to get through and let the lake breathe a bit.

"Without the aeration system, the oxygen gets so low during winter," Peterson said.

The city only uses the aeration system on Battle Creek Lake, Peterson said, because it and Powers Lake are the only two with regular fishing use. Powers Lake is deeper and doesn't require aeration, he said.

There will be a hole in the ice where the aeration system is working, but people will still be able to use the rest of Battle Creek Lake, he said.

The system is operated in the north central part of the lake near the end of Edgewood Avenue, adjacent to the public access area in Shawnee Park. It will be working until the ice is out in spring. The city has had some form of aeration system on the lake since the early 1980s, Peterson said. It used to be a paddlewheel system until the new pumps were put in place in 2002.

Signs will be posted near the thin ice, alerting ice fishermen and snowmobilers of the danger, Peterson said. The lake is "fairly heavily" used for recreation, he said, and the city wants people to take note of the conditions.

When it comes to ice safety in general, the major snowstorm last weekend didn't help matters, according to Tim Smalley, Department of Natural Resources boat and water safety specialist. And Monday's snowfall means conditions won't get much better.

The lakes are "pretty well frozen over," he said, but there is only 6-8 inches of ice on most metro area lakes. The snow insulates the ice and keeps it from freezing as quickly, Smalley said, noting that there have already been two fatalities on Minnesota lakes this winter.

Heavy snow can press down on the ice and cause water to creep to the surface through fissures and create slush in which snowmobiles can get stuck, he said.

"Slush is really a nuisance and can be dangerous," Smalley said.