New fish barrier will keep carp out of Forest Lake

Would you eat green carp and ham? Would you eat it in a Dodge Ram? Or in an ice house or on an ice dam?

When European settlers immigrated to the United States during the 1600s, 1700s and 1800s, they brought along seeds for crops, chickens to lay eggs, and an assortment of animals to ensure that they would have plenty to eat in their new homeland. Some of these imports – wheat and cows for example – remain staples of our modern American food system. Others have fallen out of favor and are now considered pests. Such is the fate of dandelions and common carp.

Common carp (Photo by Star Tribune)

Common carp, which are native to Europe and Asia, were intentionally introduced to lakes in the Midwest as a game fish during the 1880s. Unfortunately, the fish proved to be a highly damaging aquatic invasive species, especially in shallow lakes and wetlands. Carp are omnivorous bottom feeders and have a nasty habit of uprooting aquatic plants. This muddies the water and releases phosphorus that is bound in the lake bottom sediment, causing a cascade of effects, including more algae growth, diminished water clarity, and less food for native fish and waterfowl.

Today, common carp are widespread throughout the continental United States (common indeed!) and are found in hundreds of lakes in central and southern Minnesota. They live in lakes, rivers, and wetlands and are often seen in the spring when they spawn in shallow waters. Worst of all, they are no longer treasured as a game fish, delicious as they may be.

Common carp spawning in shallow water (Photo by L. Beesley)

The Comfort Lake – Forest Lake Watershed District (CLFLWD) implements a variety of strategies to control common carp and minimize harm to local lakes. One of the most effective is to operate fish barriers at the inlets and outlets of Bone and Forest Lakes to prevent carp from migrating into surrounding wetlands to spawn. The watershed district also operates winter aeration systems on Moody and Shields Lakes. The aeration systems increase oxygen levels during the winter so that more game fish survive. These game fish eat bullheads and small carp and help to naturally control their populations. CLFLWD has also conducted fish population surveys on Bone, Moody and Shields Lakes and has worked with contractors to net and remove carp on several occasions.

Winter carp harvest on Bone Lake (Photo from CLFLWD)

This February, CLFLWD replaced an old, dilapidated fish barrier on the northwest side of Forest Lake, where the lake outlets to the Sunrise River. A concrete weir, also located at the outlet, controls the water level on Forest Lake. The new fish barrier is attached to the weir but will not affect water levels. It will, however, prevent carp and other rough fish from migrating into Forest Lake.

A new fish barrier was installed where Forest Lake outlets to the Sunrise River. (Photo by CLFLWD)

For more information on projects and programs of the Comfort – Lake Forest Lake Watershed District, head to or attend a Board of Directors meeting, held online at 6:30pm on the second and fourth Thursdays of the month.