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LOCATION--Lat 42°27’11.13", long
71°08’07.24", Middlesex County, Hydrologic Unit 01090001, on
left bank, 50 ft upstream from Mt Vernon Street at Winchester.
DRAINAGE AREA--Total above gage, 24.5 mi2; net above gage, 23.9 mi2,excludes 0.6 mi2 drained by Winchester North Reservoir. Drainage area prior to gage relocation, 24.7 mi2; net above gage, 24.1 mi2. Minor decrease in drainage area at new gage location is less than one percent from original gage location so all discharge data from original gage location apply to new gage location.
PERIOD OF RECORD--April 1939 to current year.
GAGE--Data-collection platform, satellite telemeter, hourly updates, with river stage and velocity sensors. Elevation of gage is about 15 ft above NAVD 1988, from digital map.
COOPERATION BY--Massachusetts Department of Conservation and Recreation, Division of Planning and Engineering.
REMARKS--On September 28, 2011, the streamgage was relocated from Mystic Valley Parkway (established April 1939) to 50 ft upstream from Mt. Vernon Street, 0.45 mi upstream from the original streamgage location on Mystic River Parkway, to enable stream channel improvements for flood mitigation efforts.
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.