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LOCATION--Lat 42° 38’45", long 71°
17’56", Middlesex County, Hydrologic Unit 01070002, on right
bank at Lowell, 1,100 ft downstream from Concord River.
DRAINAGE AREA--Total above gage, 4,635 mi2; net above gage, 4,421 mi2—excludes 214 mi2 for use of Boston metropolitan district and city of Worcester.
PERIOD OF RECORD--Discharge: June 1923 to current year.
Water-quality records: Water years 1954, 1966–74, 1999.
GAGE--Data Collection Platform with satellite telemeter. Datum of gage is 5.18 ft above National Geodetic Vertical Datum of 1929. Prior to Mar. 7, 1934, at Boot Mills, 1,800 ft upstream and 700 ft above mouth of Concord River, in same gage pool and at same datum; gage-height record (provided by Proprietors of the Locks and Canals on Merrimack River) was indicative of flow including that of Concord River.
REMARKS--Daily discharge includes water released from 210 mi2 in basins of Sudbury and Nashua Rivers and Lake Cochituate. Flow regulated by powerplants, by Franklin Falls Reservoir since 1942, and by Squam, Newfound, Winnipesaukee, Winnisquam, and other lakes and reservoirs upstream.
COOPERATION BY--Massachusetts Department of Conservation and Recreation, Office of Water Resources.
ICE EFFECTS ON STREAMFLOW During winter, ice formation in streams can cause stage and corresponding discharge values to appear higher than expected during periods of no precipitation. Ice effects from partial ice cover or shore ice may be minor, where stage and discharge appear to increase at night and decrease to base-line conditions around midday for one or more days. Major ice effects from complete ice cover appear as constantly increasing stage and discharge over several days during prolonged cold periods. Stage and discharge values for streams experiencing minor ice effects will continue to be displayed on the web to enable the user to estimate the approximate base-line discharges. Note that this method of estimation should only be used when no runoff occurs. During periods of major ice effects, display of discharge data on the web will be temporarily discontinued to prevent misuse of erroneous discharge data. The discharge record will resume when it is determined that ice conditions are no longer present. Display of stage data during periods of minor and major ice effects will continue to be displayed on the web. Daily mean discharges will be estimated for all periods of ice-effected discharges.
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