SUSTAINABILITY ANALYSIS OF WILBER LAKE AND THE LOWER RESERVOIR, ONEONTA, NY, USA

Increases in population growth, urbanization, and climate change have hastened the need to maximize the overall societal benefit from existing freshwater reservoirs. However, reservoir sedimentation has severely limited their productivity and life expectancy. The problem is currently manifesting in the New England, New York, and elsewhere across the earth and needs a low-cost means to evaluate the issue.

As a case study, the impacts due to sedimentation on the sustainability of, the city of Oneonta’s, Wilber Lake and Lower Reservoir are evaluated. Therefore, we conducted a low-cost, high-frequency (455-800 kHz and 1,2MHz) bathymetric CHIRP sonar survey using a Humminbird HELIX 9 linked with ReefMaster software to produce bottom feature and bathymetric maps, sub-bottom substrate profiles, and determine water and sediment volumes of the lake and reservoir to evaluate the sustainability of a freshwater reservoir system.

Approximately, 27,213 m³ of fluvial sediments derived from Oneonta Creek fill the Lower Reservoir, and an estimated 101,131 m³ of lacustrine sediments, derived from minor streams and farm runoff, fill Wilber Lake. Estimated pre-sedimentation volume of Wilber Lake is 1,667,720 m³ and the Lower Reservoir is 40,808 m³ with lost capacity of ~27,234 m³. Current estimated available water is 451x10⁶ gal, the average used is 399x10⁶ gal, and an average storage loss of 0.01% per year. Sediment transport, and siltation patterns in the Lower Reservoir are principally controlled by late fall and spring flash floods, which deliver sediments to the reservoir in the stream intake area (deposition thickness ~6m) and in the middle and dam areas 3 and 2 m respectively. Therefore, current bathymetry and usage data indicate no immediate risk to water supply, but planning should commence for the future. Finally, this study further demonstrates and supports other studies showing the usefulness of the low-cost CHIRP sonar units currently available.