PROVISIONAL DATA SUBJECT TO REVISION

STATION.--01638500  POTOMAC RIVER AT POINT OF ROCKS, MD
LOCATION.--Lat 39°16'24.9", long 77°32'35.2", Frederick County, Hydrologic Unit 02070008,
   on left bank at downstream side of bridge on U.S. Highway 15 at Point of Rocks, 0.3 mi downstream from
   Catoctin Creek (Virginia), 6 mi upstream from Monocacy River, and at mile 159.5.
DRAINAGE AREA.--9,651 mi2.
PERIOD OF RECORD.--February 1895 to current year.
REVISED RECORDS.--WSP 192:  1895-1905.  WSP 1432:  1899, 1901-2, 1904-5, 1912, 1914(M), 1915, 1917(M),
   1918, 1919(M), 1920, 1921-23(M), 1924, 1925-28(M), 1930(M).
GAGE.--Water-stage recorder.  Datum of gage is 200.63 ft above National Geodetic Vertical Datum of 1929.
   Prior to Oct. 28, 1929, nonrecording gage at same site. Prior to Sept. 2, 1902, at datum about
   0.45 ft higher.
REMARKS.--Low flow affected slightly from 1913 to July 1981 by Stony River Reservoir; since December 1950
   by Savage River Reservoir (see station 01597500); and since July 1981 by Jennings Randolph Lake. Low flow
   affected extensively at times by run-of-the-river hydroelectric plants.  National Weather Service gage-height
   telemeter at station.
   U.S. Geological Survey satellite collection platform at station.
EXTREMES FOR PERIOD OF RECORD.--Maximum discharge, 480,000 ft3/s, Mar. 19, 1936,
   gage height, 41.03 ft; minimum discharge, 530 ft3/s, Sept. 11, 12, 1966.
EXTREMES OUTSIDE PERIOD OF RECORD.--Flood of June 2, 1889, reached a stage of 40.2 ft, from floodmarks,
   discharge, about 460,000 ft3/s.
COOPERATION.--Funding for the operation of this station is provided by the Interstate Commission on the Potomac
   River Basin, and the U.S. Geological Survey.