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ICE EFFECTS ON STREAMFLOW
The formation of ice on rivers can cause discharge values to appear unusually high. Display of these erroneous discharge data may result in improper assessment of flow conditions and misuse of the data. For this reason, display of discharge values for streams significantly affected by ice may be disabled from view. Display of discharge data will resume when ice conditions are no longer present. Discharge values for streams minimally affected by ice will continue to be displayed. Flows for streams with these conditions appear to increase during the night and decrease to near-base-line conditions around midday. To estimate the correct discharge for these streams, use the flow rate that corresponds to the bottom of the discharge curve, rather than the peak that corresponds to the top of the curve. Note that this method of estimation is possible only when no surface runoff is occurring. Daily mean discharges for periods of both significant and minimal ice-effect will be estimated and published in the Annual Water-Data Report for the water year in which they occurred.
LOCATION--Lat 42°26’50.5", long
71°08’18.9", Middlesex County, Hydrologic Unit 01090001, on
left bank, 0.3 mi downstream from Waterfield Street at
DRAINAGE AREA--Total above gage, 24.7 mi2; net above gage, 24.1 mi2, excludes 0.6 mi2 drained by Winchester North Reservoir.
PERIOD OF RECORD--April 1939 to current year. Streamgage temporarily relocated to Mt. Vernon Street from September 2011 to April 2014 during river channel improvements for flood mitigation at Mystic Valley Parkway.
GAGE--Data-collection platform, satellite telemeter, hourly updates, with river stage and velocity sensors. Elevation of gage is about 8 ft above NAVD 1988, from digital map.
COOPERATION--Massachusetts Department of Conservation and Recreation, Division of Planning and Engineering.