Date: Thu, 17 Apr 2014 15:49:31 EDT
Summary: Major and Moderate Flooding in Northern New York
Major flooding continues along the Schroon R at Riverbank, NY and Moderate flooding continues along the Black R at Watertown, NY. Streamflows are receding at all USGS streamgages in Northern New York with only the Schroon R at Riverbank and Black R at Watertown streamgages presently exceeding NWS Flood Stage.
Areas hardest hit by runoff from a deep snow pack in the Adirondack Mountains included the Schroon R, Upper Hudson R, Upper Mohawk R, Black R, Raquette R, St Regis R, Oswegatchie R, and Lake Champlain basins. The provisional AEP’s in many basins in northern New York ranged from 10% to 4% (10-yr to 25-yr recurrence intervals).
The Schroon R at Riverbank streamgage peaked earlier today at about 7,000 cfs with a provisional annual exceedance probability (AEP) of about 10% (10-year recurrence interval).
The Black R at Watertown streamgage peaked earlier today at about 42,000 cfs with a provisional AEP of about 2% (50-year recurrence interval). This would be the 3rd highest peak in 115-yrs. (1998=55,500 cfs and 1993=42,600 cfs). A USGS crew made a discharge measurement shortly after the peak using a 200-lb sounding weight to stabilize the velocity meter in the turbulent, swift current.
The W Br St Regis R nr Parishville, NY streamgage recorded a record peak discharge (6,300 cfs) on April 15 with a provisional AEP of 1% (100-yr flood). The gage has been in operation since 1958 (55-yrs of record).
The Hudson R at Newcomb, NY streamgage recorded the 3rd highest peak discharge (8,000 cfs) since 1925 (88-yrs) on April 16 with a provisional AEP of 2% (50-yr flood).
Seven USGS crews (14 staff members) from the Troy, NY and Potsdam, NY offices of the New York Water Science Center have made about 50 discharge measurements at about 35 streamgages during the past three days to document the conditions and calibrate stage-discharge relationships at USGS streamgages.