Deer Lake is a 457-acre mesotrophic (moderately fertile) lake located in central Otter Tail County approximately five miles north of Battle Lake, MN. Deer Lake is connected to Otter Tail Lake via the Otter Tail River. The immediate watershed is composed primarily of agricultural land interspersed with hardwood woodlots. The maximum depth is 26 feet; however, 67% of the lake is 15 feet or less in depth. The secchi disk reading, which is a standard measure of water clarity, was 9.8 feet during the 2009 survey. Previous secchi disk readings have ranged from 5.5 to 9.5 feet. The majority of the shoreline of Deer Lake has been extensively developed. A DNR owned public access is located on the southeast shoreline where the Otter Tail River enters the lake. There are remnant stands of hardstem bulrush and wild rice in the shallow areas of the lake. These emergent plants provide valuable fish and wildlife habitat and are critical in maintaining good water quality. They protect shorelines and lake bottoms from wave erosion and help absorb excess nutrients. Emergent plants also provide critical spawning habitat for several fish species including northern pike, largemouth bass and panfish. They also serve as important nursery areas for many species of fish. Because of their ecological value, emergent plants cannot be removed without a DNR permit. With recent high water levels, shoreline erosion has become an increasing concern for lakeshore owners. By using shoreline best management practices (BMP's) and lakescaping concepts, impacts of development and shoreline erosion can be minimized. Contact any County Extension Office for information on BMP's and the local DNR Fisheries Office for information on lakescaping techniques. The northern pike test-net catch rate was within the expected range for similar lakes. Age and length data from recent surveys indicate that northern pike reproduction is consistently good and that the population is dominated by young fish. Northern pike ranged in length from 9.5 to 29.8 inches with an average length and weight of 17.2 inches and 1.2 pounds. Northern pike reach an average length of 22.1 inches at age four. The bluegill test-net catch rate was within the expected range for similar lakes but was the lowest recorded since the 1979 survey. Bluegill size structure remains poor with 13% of the sample measuring 7.0 inches or greater in length. Bluegills reach an average length of 6.5 inches at age six. The walleye test-net catch rate was within the expected range for similar lakes. Walleye ranged in length from 13.1 to 24.2 inches with an average length and weight of 16.1 inches and 1.4 pounds. Walleye reach an average length of 14.2 inches at age four.