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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°35'06.1", long 70°49'14",
Essex County, Hydrologic Unit 01090001, 45 ft west of State Highway 128
and 120 ft northeast of Grapevine Road in Wenham, MA.
AQUIFER--Sand and gravel, glaciated regions; outwash deposits.
WELL CHARACTERISTICS--Drilled observation water-table well, depth 21.97 ft, screened 18.8 ft to 21.8 ft.
INSTRUMENTATION--Digital recorder with cellular telephone telemeter, May 2012 to July 2018 (WPW 76), July 2018 to current year (WPW 76R). Monthly measurements prior to May 2012.
DATUM--Elevation of land-surface datum of well is 60 ft above National Geodetic Vertical Datum of 1929, from topographic map. Measuring point: top of well casing, 2.82 ft above land-surface datum.
PERIOD OF RECORD-- November 1964 to current year.
COOPERATION BY--Massachusetts Department of Conservation and Recreation, Office of Water Resources.