During 2015, the U.S. Geological Survey, in cooperation with the City of Ithaca, New York, and the New York State Department of State, conducted a bathymetric survey of the lower Sixmile Creek reservoir in Tompkins County, New York. A former water-supply reservoir for the City of Ithaca, the reservoir is no longer a functional component of Ithaca’s water-supply system, having been replaced by a larger reservoir less than a mile upstream in 1911. Excessive sedimentation has substantially reduced the reservoir’s water-storage capacity and made the discharge gate at the base of the 30-foot dam, which creates the reservoir, inoperable. U.S. Geological Survey personnel collected bathymetric data by using an acoustic Doppler current profiler. Across more than half of the approximately 14-acre reservoir, depths were manually measured because of interference from aquatic vegetation with the acoustic Doppler current profiler. City of Ithaca personnel created a bottom-elevation surface from these depth data. A second surface was created from depths that were manually measured by City of Ithaca personnel during 1938. Surface areas and storage capacities were computed at 1-foot increments of elevation for both bathymetric surveys. The results indicate that the current storage capacity of the reservoir at its normal water-surface elevation is about 84 acre-feet and that sediment accumulated between 1938 and 2015 has decreased the reservoir’s capacity by about 68 acre-feet. This sediment load is attributed to annual inputs from the watershed above the reservoir, as well as from an episodic landslide that filled a large part of the reservoir along its northern edge in 1949.
Citation Information
Publication Year | 2016 |
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Title | Bathymetric survey and estimation of storage capacity of lower Sixmile Creek reservoir, Ithaca, New York |
DOI | 10.3133/ofr20161157 |
Authors | John F. Wernly, Henry J. Zajd, Jr., William F. Coon |
Publication Type | Report |
Publication Subtype | USGS Numbered Series |
Series Title | Open-File Report |
Series Number | 2016-1157 |
Index ID | ofr20161157 |
Record Source | USGS Publications Warehouse |
USGS Organization | New York Water Science Center |
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Geospatial data set of bathymetric survey of lower Sixmile Creek Reservoir, Ithaca, New York, 2015
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Geospatial data set of bathymetric survey of lower Sixmile Creek Reservoir, Ithaca, New York, 2015
Water depths were measured during November 2015 and bathymetric elevations were computed for the lower Sixmile Creek reservoir in Ithaca, Tompkins County, N.Y. These data were used to create a bathymetric surface (TIN) of the reservoir. Data collected in 1938 were used to create a second TIN and a contour line shapefile. This dataset includes the ADCP-measured transect data and manually-measured p - Connect