Horseshoe Lake is in Ecological Lake Class 19, which consists of 66 lakes in northeast Minnesota that are small, shallow, and have moderately hard (mineralized) water. Horseshoe Lake has clearer water than many of the lakes in this lake class.According to Carlson's Trophic State Index, Horseshoe Lake ranks as mesotrophic with a Secchi water clarity of 3.4 m, total phosphorus at or below the detection limit of 20 ppb, and chlorophyll-a of 6.1 ppb. Summer algae blooms have declined in recent years, according to a local resident in 2002. Horesehoe Lake was slightly thermally stratified on 07/01/2002 with a surface temperature of 79 F and a bottom temperature of 68 F. Adequate oxygen for fish (more than 2 ppm) was retained to a depth of 10 ft, where the temperature was 69 F.One small inlet is from Mud Lake. The outlet to Long Lake is shallow, but navigable by canoe or small boat. Lake bottom substrates along the shoreline of Horseshoe Lake are mostly sand, with some gravel and muck. Aquatic plants are abundant in a fringe around the entire shoreline and grow to a depth of 6 ft; the most common plants are coontail and yellow waterlily. Other common plants are filamentous algae, northern milfoil, duckweed, flat-stem pondweed, bulrush, and cattail. Curly-leaf pondweed was present in 2002 and has been present in adjacent Long Lake for several years. It is not native to this area, and was not observed in previous fisheries lake surveys in 1959 and 1977.There is no public access to Horseshoe Lake. The 2002 fisheries lake survey crew used a private access. There were 23 homes and cabins on the lake in 2002. A central sewer collector was installed around Long Lake in 2001 and comes close to some of the homes on Horseshoe Lake; three year-round homes and one seasonal cabin on Horseshoe Lake are now connected to this sewer collector.Fish sampling in this investigation consisted of two gillnet sets and nine trapnet sets. Small mesh (1/4") trapnets were used in lieu of shoreline seining due to the thick vegetation along the shoreline. Three previous investigations dating back to 1959 each consisted of 2-3 gillnets and 4 trapnets.The total catch of fish (all species combined) in the trapnets in 2002 of 57.8 fish/net (18.2 lb/net) was similar to the median catch of 68.8 fish/net (24.9 lb/net) in all investigations on this lake. The trapnet catch in 2002 was dominated by bluegill and black crappie.The total catch of fish in the gillnets in 2002 of 22.5 fish/net (33.3 lb/net) was in the second quartile for this lake class and was similar to the median catch of 24.8 fish/net (38.0 lb/net) in all investigations on this lake. The gillnet catch in 2002 was dominated by northern pike.Bluegill numbers in 2002 (48.0/trapnet) were in the fourth quartile for this lake class. Bluegill numbers appear to have increased over time from an average of 14/trapnet in the first two investigations, to an average of 40/trapnet in the two most recent investigations. However, the first two investigations were done in late August and early September, while the two most recent investigations were done in early July. Sunfish are more likely to be caught in trapnets early in the summer. Bluegill sizes in 2002 averaged 6.2" (0.20 lb), which was near the median for this lake class and was larger than the average size of 5.6" in all investigations on this lake. The largest bluegill in 2002 was 9.9", and three percent were 8" or larger. Growth of bluegill was in the second quartile for young fish and in the third quartile for older fish, by area standards.Black crappie numbers in 2002 (5.8/trapnet) were in the fourth quartile for this lake class and were similar to the median catch of 6.2/trapnet in all investigations on this lake. Crappie sizes in 2002 averaged 9.5" (0.50 lb), which was in the third quartile for this lake class and was larger than the average size of 7.7" in all investigations on this lake. The largest crappie was 12.2". Most crappie in 2002 (62%) were four years old, from a strong 1998 year class. Growth of crappie was faster than normal (in the third and fourth quartiles, depending on age) by area standards.Northern pike numbers in 2002 (11.5/gillnet) were in the fourth quartile for this lake class and were higher than the median catch of 8.5/gillnet in all investigations on this lake. Pike sizes in 2002 averaged 21.2" (2.4 lb), which was in the third quartile for this lake class and was smaller than the average size of 23.5" in all investigations on this lake. The largest pike was 33.8". Growth of pike was near the median by area standards.Many of the bluegill and northern pike examined in 2002 were infected with neascus. Some of the perch were infected with yellow grub. Neascus (black spot) and yellow grub are common parasites that are native to the area. They cannot infect humans, are often removed by filleting, and are killed at temperatures used to cook fish.