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- Water-Year Summary reports summarize a year of hydrologic data in a printer-friendly format.
- For water years 2014 onward, choose a water year and parameter and an on-demand Water-Year Summary report will be generated.
- For water years 2006 through 2013, choose a water year and an Annual Water Data Report will be provided.
- For water years 2005 and earlier, Annual Water Data Reports may be available in digital format.
- Not all sites have reports available for every water year.
USGS Water-Year Summary 2024
01661500 ST MARYS RIVER AT GREAT MILLS, MD
LOCATION - Lat 38°14'30.3", long 76°30'13.2" referenced to North American Datum of 1983, St. Mary's County, MD, Hydrologic Unit 02070011, on left bank at downstream side of bridge on State Highway 471 (Indian Bridge Road) in Great Mills (formerly Clifton Mills), 0.3 mi downstream from Western Branch, and 12.0 mi upstream from mouth.
DRAINAGE AREA - 24 mi².
REVISIONS HISTORY - WSP 1702: 1946, 1948-49, 1955, 1957-58. WDR MD-DE-83-1: 1981-82(M).
SURFACE-WATER RECORDS
PERIOD OF RECORD - June 1946 to September 2005. October 2006 to current year.
GAGE - Water-stage recorder, crest-stage gage, and concrete control. Datum of gage is 6.86 ft above North American Vertical Datum of 1988.
REMARKS - Water Year 2023: Records good. No estimated discharges.
Water Year 2022: Records fair, no estimated discharges.
Water Year 2021: Records good, except those for estimated discharges, which are poor.
Water Year 2020: Records good. No estimated discharges.
Water Years 2018-2019: Records good, except those for estimated discharges, which are poor.
Water Year 2017: Records fair, except those for the period June 29-September 30, which are good, and those for estimated discharges, which are poor.
Water Year 2016: Records fair, except those for the period October 1-December 1, which are good, and those for estimated daily discharges, which are poor.
Water Years 2014-2015: Records good, except those above 1,000 ft³/s, which are fair, and those for estimated daily discharges, which are poor.
Water Year 2013 and prior years’ accuracy statements can be found in Annual Water Data Reports.
Occasional regulation by reservoir on Western Branch of St. Marys River, 2.0 mi upstream since 1975, total capacity 3,200 acre-feet. U.S. Geological Survey satellite data-collection platform at station.
Occasional regulation by reservoir on Western Branch of St. Marys River, 2.0 mi upstream since 1975, total capacity 3,200 acre-feet. U.S. Geological Survey satellite data-collection platform at station.
