Movement of carp, bullheads targeted at lakes near Washington-Chisago border
For years, carp and bullheads wreaked havoc on Bone and Moody lakes, which straddle the border between Washington and Chisago counties. The rough fish uprooted native aquatic plants and stirred up sediment on the lake bottoms, muddying the water and releasing nutrients like phosphorus, which in turn contributed to algae blooms during the late summer and fall.
Now, thanks to efforts of the Comfort Lake – Forest Lake Watershed District (CLFLWD), two low-velocity fish barriers are in place that will prevent fish from migrating into and out of the lakes, effectively putting an end to the rough-fish rampage.
The district began a five-year project to improve Bone and Moody lakes in late 2010 when it harvested more than 23,000 pounds of carp from Bone Lake and 3,600 small bullheads from Moody Lake. Since then, the water has been clearer and there is better habitat for desirable fish and wildlife like turtles and birds due to more abundant native aquatic vegetation. Without the newly constructed barriers in place, however, the carp and bullhead populations would likely explode again within only a few years.
Recent research has found that carp move into shallow lakes and wetlands to spawn. Bluegills and other panfish usually eat many of the carp eggs, but when winter kills eliminate bluegill populations, the carp are able to quickly reproduce and repopulate a lake.
The two low-flow fish barriers, funded in part by a $283,000 Conservation Partners Legacy Grant from the Minnesota Department of Natural Resources, as part of the Lessard Sams Outdoor Heritage Fund, will also prevent the fish from moving into wetlands to spawn. Although the barriers will keep fish out, they will have no effect on water levels.
Next year, CLFLWD will begin work on developing an aquatic vegetation management plan for Bone Lake which could result in chemical treatments to control curly leaf pondweed. That invasive species can be a large source of phosphorus when it dies off in late June and July.
At the same time, the district hopes to work with shoreline homeowners and nearby landowners whose property drains to the lakes to install shoreline plantings, plant rain gardens, repair gullies and control erosion so that less sediment and phosphorus ends up in the water. The long-term goal is to reduce phosphorus by 1600 pounds per year, equivalent to 800,000 pounds of algae, so that both lakes meet Minnesota’s water quality standards by 2019.
Grants and free design assistance are available for nearby landowners to complete shoreline plantings, rain gardens and other clean water projects. For more information, visit www.clflwd.org or contact Doug Thomas at [email protected] or (651) 209-9753.