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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°45'19.3", long
70°56'22.2", Essex County, Hydrologic Unit 01090001, 300 ft
east of Interstate Highway 95 and 100 ft north of Central Street in
AQUIFER--Glacial till, glaciated regions.
WELL CHARACTERISTICS--Dug observation water-table well, diameter 31 in, depth 19.8 ft, cased with ceramic tile, open end.
INSTRUMENTATION--Digital recorder with satellite telemeter, December 2013 to current year. Recorded data October 1984 to December 2013. Graphic recorder with 5-day data, January 1967 to September 1982. Monthly measurements prior to January 1967.
DATUM--Elevation of land-surface datum of well is 55 ft above National Geodetic Vertical Datum of 1929, from digital map. Measuring point: top of hole in base of shelter, 2.15 ft above land-surface datum.
PERIOD OF RECORD-- February 1965 to current year.
COOPERATION BY--Massachusetts Department of Conservation and Recreation, Office of Water Resources.