Annual water levels fluctuate between 363.5 and 364.5 m above sea level, with 364.1 m considered normal. Water levels have been recorded daily since 1974. Figure 13 illustrates typical spring (high water) conditions. The maximum elevation recorded since 1974 was +91 cm (36") above normal, or 365 m above sea level, on April 28, 1983. This broke the previous high of +87 cm (34") that occurred on March 17, 1977. That same level (+87 cm) was again reached during the week of April 11, 1993. Low levels have not shown such amplitudes, never exceeding the range mentioned above (Harman, 1992a, b; Harman, 1993a; Harman and Ernst, 1994).
Water levels have been artificially controlled by the Village of Cooperstown at a dam located there since 1905. However, periods of heavy rainfall and/or snow melt or dry weather create conditions to which the dam is incapable of responding (Palmer, 1975).