Grass Lake is a small lake in northwestern Wright County with surface area of 92 acres and a maximum depth of 35 feet. The Clearwater River flows through Clearwater Lake and into Grass Lake via a short, navigable channel and exits Grass Lake on the north end over a small low head dam; no other public access exists. The Clearwater River flows into the Mississippi River at the town of Clearwater, past a larger dam that is a barrier to fish movement. The watershed is large and dominated by agriculture. The lake is primarily managed for Northern Pike and Largemouth Bass. This is the first survey since 2005.
Emergent vegetation was abundant; cattail and white waterlily were the dominant species along shore. No submergent plant survey was done in 2014, but coontail, chara, and northern milfoil were predominant in 2005 and submerged vegetation was abundant in 2014. Eurasian watermilfoil was not found in the 2005 survey, but is now widespread in Clearwater Lake and likely exists in Grass Lake. Water clarity was good; Secchi depth was 7.0 feet in August 2014.
Northern Pike catch rates were similar between 2014 and 2005 and remained within the expected range of values for lakes similar to Grass Lake. Northern Pike in 2014 ranged in length from 15.0 to 31.2 inches with an average length and weight of 20.5 inches and 1.7 pounds. Although catch rates were similar, only 11% of Northern Pike in 2014 were longer than 24 inches versus 28% in 2005.
Largemouth Bass were surveyed in May by daytime boat electrofishing. The catch rate was well below the Montrose Area average. Largemouth Bass lengths ranged from 9.2 to 18.4 inches with an average length of 13.6 inches. Of the catchable size fish (> 8 inches) caught, 46% were longer than 15 inches; however, only 11 fish were captured.
The Bluegill catch rate was lower than 2005, but still in the expected range of values for similar lakes. Bluegill lengths ranged from 2.4 to 8.4 inches; average length and weight were 5.1 inches and 0.12 pounds. Black Crappie were caught in low numbers (below the expected range) in 2014 and catch rates in 2005 were similarly low. Black Crappie lengths ranged from 7.5 to 10.0 inches with an average length and weight of 9.3 inches and 0.52 pounds. Only seven Black Crappie were caught in the survey.
One Walleye was captured in the survey; Walleye are stocked in Clearwater Lake and some likely migrate to Grass Lake. Only one Yellow Perch was sampled; Yellow Perch catches have been very low since the 1985 survey. Other species captured included: Bowfin (Dogfish), Brown Bullhead, Hybrid Sunfish, Pumpkinseed, Rock Bass, White Sucker, and Yellow Bullhead.
- Zebra Mussel
Recreational activities such as recreational boating, angling, waterfowl hunting, and diving may spread aquatic invasive species. Some aquatic invasive species can attach to boats, while others can become tangled on propellers, anchor lines, or boat trailers. Many species can survive in bilge water, ballast tanks, and motors or may hide in dirt or sand that clings to nets, buckets, anchors, and waders. Fortunately, completing simple steps can prevent the transport of aquatic invasive species.