Also at this time, the Otsego County Conservation Association (OCCA) was formed by a group of local landowners and sportsmen concerned about the water quality.

[3] The lake is the source of the Susquehanna River, which flows south through New York, Pennsylvania and Maryland before emptying into the Chesapeake Bay.

[10]: 29 Sunken Island is a submerged sandy plot located near the western shore of Otsego Lake, approximately six miles (9.7 km) north from Cooperstown.

[12][30] About 10,000 and 12,000 years ago, during the Wisconsin glaciation, a glacier slowly moved through and carved out a valley that Otsego Lake now sits in.

[33] A small parcel of land near Council Rock was presented to the Village of Cooperstown in 1957, on the condition that it remain open to the public as a park.

[34] Pieter Quackenboss, Jr (1710–1774), an early settler of the Mohawk Valley, dealt extensively with the natives and became known as "The Old Indian Trader."

The following incident in his life is recorded in the 1848 book Women of the American Revolution: Pieter Quackenboss was among the early settlers of the [Montgomery] County, and did not escape the difficulties.

They were disposed to bestow on him some particular mark of regard, and after meeting for consultation, they decided on giving him the name " Otsego" and christening the lake for him.

It is probable that few are acquainted with this origin of the name of Otsego Lake; but that family tradition has been confirmed by the recollection of some who witnessed the occurrence.

[35]Early in 1779, General James Clinton and his soldiers began to haul 208 boats and all their supplies from the present day Villages of Fort Plain and Canajoharie, along the Mohawk River, towards Otsego Lake.

By the end of June, they had made it to the lake and began to build a temporary dam at the outlet to raise the water level.

The purpose of this was to break the dam and ride the flood water down the river to meet General John Sullivan at Tioga.

This event is described by James Fenimore Cooper in the introduction to his popular novel The Pioneers, and commemorated by a Memorial Day canoe race.

Cooper stated: A singular event deemed sent by a good Providence to our relief; it was reported to me that unusual shoals of fish were seen moving in the clear waters of the Susquehanna.

Also at this time, the Otsego County Conservation Association (OCCA) was formed by a group of local landowners and sportsmen concerned about the water quality.

Short term problems occur as well, as lake trout were studied and found that they were not using their normal spawning beds, due to being buried in silt.

[5]: 1 Otsego Lake is chemically eutrophic, which means that it is rich in nutrients and supports a dense plant population, the decomposition of which kills some animal life by depriving it of oxygen.

It is also morphometrically oligotrophic, which means that its large size causes it to appear and function as a nutrient-poor lake although it receives a fair amount of nutrients.

[43]: 1  It is the headwaters of the 27,510-square-mile (71,300 km2) drainage basin of the Susquehanna River which runs from Otsego Lake in Cooperstown to Havre de Grace where it flows into the Chesapeake Bay of the Atlantic Ocean.

[4][47] SUNY Oneonta maintains a Biological Field Station (BFS) that regularly takes phosphorus samples around the lake.

[49]: 5  In 1935, as part of a wider survey of the Delaware and Susquehanna watersheds, the New York State Conservation Department studied the plankton, fish, plants, and physical and chemical properties of Otsego Lake.

[2] In 1968, access to the lake and a location to build a field station and biological research facility were acquired by SUNY Oneonta.

[4]: 6  In 1999, the village of Cooperstown received a $5,600 grant from the NYSDEC, to purchase lighted buoys to mark a no-wake zone, that extends 200 feet (61 m) from shore.

[4]: 7 Zebra mussels were first introduced into the Great Lakes in the mid- to late-1980s from ballast discharged from freighters originating in the Black and Caspian Sea region of eastern Europe and western Asia.

[2] In a 2013 study of the lake, other invasive species were found, including eurasian milfoil, japanese knotweed, purple loosestrife, curly leaf pondweed, rusty crayfish, and starry stonewort.

In early 2017, BFS researchers installed transponder tags in 500 adult walleyes while they spawned in tributaries at the north end of the lake.

[59] Another swimming area is Fairy Springs and is located one mile of Cooperstown along the eastern shore of the lake accessible via County Road 31.

In The Deerslayer, Three Mile Point is the location where Hetty Hutter docks to seek the Huron Indian camp which was further south at Muskrat Cove.

[12][66][67] Otsego Lake is also referenced in The Secret of Mirror Bay, a novel in the Nancy Drew Mystery Stories series.

In the story, Aunt Eloise invites Nancy and her friends to a cabin at Mirror Bay, in Cooperstown, to solve a case of a mysterious woman seen gliding across the water.