Funding for this site is provided by:
LOCATION.--Lat
42°45'08", long 73°41'20" referenced to North
American Datum of 1983, Albany County, NY, Hydrologic Unit 02020003, on
right bank at Green Island, just upstream from Troy Lock and Dam, and
0.5 mi downstream from 5th branch Mohawk River.
DRAINAGE AREA.--8,090 mi². approximately (including that above
site of former auxiliary gage).
PERIOD OF RECORD.--February 1946 to current year (October 1997
to September 2000, discharges only for days when inflatable rubber dam
was considered to have been collapsed; see REMARKS).
REVISIONS HISTORY.--2014. 2016: Datum.
GAGE.--Water-stage recorder. Datum of gage is 0.18 ft below NGVD
of 1929 and 0.92 ft below NAVD of 1988. From July 1, 1946 to Mar. 12,
1962, auxiliary water-stage recorder on bypass channel at datum 10.59
ft higher. Power transducer on each turbine in powerplant. Since Oct.
1, 2008, auxiliary acoustic velocity meter about 1,600 ft upstream from
base gage.
COOPERATION.--Information on turbine operation provided by Green
Island Power Authority.
REMARKS.--Records include flow over spillway, flow through lock,
and flow through powerplant. Powerplant, located on the right bank just
downstream from gage, was inoperative from Nov. 20, 1960 to Feb. 23,
1971. An inflatable rubber dam was installed on the spillway during
August 1991 and became inoperative in August 2011. August 1991 through
September 1997, and since October 2000, estimated water-discharge data
based on records for Hudson River above Lock 1 near Waterford (station
01335754) and Mohawk River at Cohoes (station 01357500). October 1997
to September 2000, discharges only for days when inflatable rubber dam
was considered to have been collapsed.
Water Years 2014-18: Records good except those for estimated daily
discharges, which are poor.
EXTREMES FOR PERIOD OF RECORD.--Maximum discharge, 181,000
ft³/s, Dec. 31, 1948, Aug. 29, 2011, gage height, 27.05 ft; minimum
discharge not determined; minimum gage height, 13.68 ft, July 6, 1981,
when pool was lowered for inspection of flashboards.
EXTREMES OUTSIDE PERIOD OF RECORD.--Flood of Mar. 19, 1936,
reached a stage of 29.48 ft at gage on opposite bank, from information
by Corps of Engineers (discharge, 215,000 ft³/s). Flood of Mar. 28,
1913, prior to construction of Sacandaga Reservoir and Troy lock and
dam, reached a stage about 0.2 ft higher upstream from former dam near
same site. Downstream from dams, flood in 1913 was about 3.3 ft higher
than flood in 1936, from information by Corps of Engineers.
Peak Flow and Stage Information
Station image