Limnology Lake Minnetonka

1 limnology

1.1 geography
1.2 hydrology
1.3 freshwater biology
1.4 environmental issues

limnology
geography

lake minnetonka formed approximately 10,000 years ago laurentide ice sheet receded northward. lake collection of kettle lakes connected channels , marshlands which, along 18 islands, comprise irregular shape , 125 miles (201 km) of shoreline. lake minnetonka divided 2 halves, upper lake in west , lower lake in east, reflect easterly flow of water in lake s watershed. deepest point of lake minnetonka 113 feet (34 m) in crystal bay. average depth of lake approximately 30 feet (9 m). surface area of 14,528 acres (59 km), lake minnetonka ninth largest lake in minnesota.

hydrology

several streams flow lake minnetonka, largest of 6 mile creek. outlet lake minnehaha creek, @ lake s eastern end. @ headwaters of minnehaha creek, gray s bay dam helps maintain average water level of 929 feet (283 m) above sea level. flow on dam ranges 0 300 cubic feet (8.5 m) per second, or daily rate of 193,881,600 gallons (733,922 m). evaporation lake minnetonka can reach high 50 million gallons (190,000 m) per day. annual evaporation lake 30 inches (76.2 cm), or 11.5 billion gallons (44,000,000 m). countered average annual rate of 28 inches (71.1 cm) of rainfall , 20 inches (50.8 cm) of surface runoff. there have been number of droughts throughout lake minnetonka s history, notably during 1930s , late 1980s. water levels reached record low of 921.78 feet (281 m) above sea level in 1937 , record high of 931.11 feet (284 m) above sea level in 2014.

lake minnetonka typically freezes on 12 18 inches (30 46 cm) of ice during winter months. median ice-out date, has been recorded on lake minnetonka since 1855, april 14. earliest recorded ice-out date march 11, 1878, , latest recorded ice-out date may 8, 1856. water surface temperatures typically peak @ around 80°f (26.7°c) in august.

freshwater biology

lake minnetonka contains black bullhead, black crappie, bluegill, bowfin, common carp, green sunfish, hybrid sunfish, largemouth bass, muskellunge, northern pike, pumpkinseed, rock bass, smallmouth bass, walleye, white sucker, yellow bullhead, , yellow perch. fish consumption guidelines have been placed on lake s bluegill, common carp, largemouth bass, northern pike, , walleye.

according local legend, sturgeon in excess of 10 feet (3 m) in length lurks beneath surface of lake minnetonka , has been sighted on more 1 occasion. these sightings have been persistent since 1980s. sturgeon referred lou.

environmental issues

lake minnetonka s environmental issues became concern after curly-leaf pondweed discovered in waters in 1900. purple loosestrife discovered in lake in 1940, eurasian water milfoil in 1987. zebra mussels discovered in lake in 2010.

lake minnetonka suffered significant sewage, fertilizer, , surface runoff pollution until 1970s. conditions have since improved, pollution fertilizer , surface runoff remains ongoing issue. water quality closely monitored.