Reports
The water resources of Cecil, Kent and Queen Anne's Counties
1958, Overbeck, R.M., Slaughter, T.H., and Hulme, A.E.
Bulletin 21
Abstract
Cecil, Kent, and Queen Annes Counties have a land area of 1,009 square miles and their permanent population was 61,612 in 1959. Ground-water data were obtained from about 2,100 wells and 26 springs, compiled from the reports of drillers and of well owners.
The mean annual precipitation is about 43 inches. The average daily consumption of ground water in the area is estimated to be about 4,000,000 gallons. The water is used almost entirely for farm and domestic purposes.
The northern part of Cecil County lies in the Piedmont physiographic province and is underlain by igneous and metamorphic rocks of Precambrian and Paleozoic (?) age, consisting of granodiorite, gabbro, metadacite, serpentine, gneiss, chlorite and mica schist. Ground water occurs chiefly under water-table conditions in fractures in the hard unweathered rock and in pores and permeable zones in the weathered rock. The source of nearly all the ground water is precipitation. About half the wells in the Piedmont are dug wells. Of the drilled wells many are less than 100 feet deep. The average yield of all wells is about 11 gallons a minute. The quality of the water is generally good, although ground water from the serpentine area is hard. At a few places iron is present in noticeable amounts. Wells commonly provide sufficient water for domestic or farm use, but large yields cannot be expected from the crystalline rocks. An aquifer test in the granodiorite showed a coefficient of transmissibility of 14,000 gallons per day per foot and a coefficient of storage of 0.003.
Kent and Queen Annes Counties and the southern portion of Cecil County are in the Coastal Plain. The Coastal Plain deposits, consisting of sand, clay, sandy clay and silt, greensand, and marls, rest on the southeastward sloping surface of the crystalline rocks. The deposits form a wedge-shaped mass of material which ranges in thickness from a few inches in Cecil County to 2,500 feet in Queen Annes County. In Cecil County their maximum thickness is estimated to be 1,700 feet, in Kent County their thickness ranges from 900 to 2,200 feet, and in Queen Annes County from 1,500 to 2,500 feet.
The Coastal Plain deposits are Cretaceous, Tertiary, and Quaternary in age. The Cretaceous rocks are of continental and marine origin; the Tertiary rocks of marine origin; and the Quaternary rocks of fluviatile and marine origin. The formations of continental origin—Patuxent, Patapsco, Raritan, and Magothy—are characterized by light-colored, buff to red, sand, silt, and clay. The sand beds are lenticular and strongly crossbedded. The Cretaceous and Tertiary marine formations—Matawan, Monmouth, Aquia, and Calvert—are characterized by dark-colored clay, silt, greensand, and marl. The Quaternary deposits consist of crossbedded sand, gravel, clay, and silt.
The most extensively used aquifers are in the Pleistocene deposits (38 percent of the wells), but the total amount of water withdrawn from these deposits is relatively small. The greatest quantity of water is probably being taken from the Aquia greensand (19 percent of the wells). The Patapsco, Raritan, Magothy, Matawan, and Monmouth formations locally are important aquifers. The Calvert formation is relatively unimportant as a source of water (1 percent of the wells).
Wells ending in the Patuxent formation have an average yield of 16 gpm; in the Patapsco, 40 gpm; in the Raritan, 35 gpm; in the Magothy, 30 gpm; in the Matawan, 38 gpm; in the Monmouth, 40 gpm; in the Aquia, 27 gpm; in the Calvert, 53 gpm; in the Wicomico, 43 gpm, and in the Talbot formation, 24 gpm.
Aquifer tests on the Patapsco formation at Elkton showed coefficients of transmissibility of 5,500 to 24,000 gallons per day per foot. A test on the Magothy at Cecilton indicated a transmissibility coefficient of 25,000 gallons per day. Tests on the Monmouth formation at Rock Hall, Massey, and Kennedyville indicate transmissibility coefficients of 4,600, 5,700 and 4,900 gallons per day respectively. Storage coefficients from these tests range from 0.0000003 to 0.0004. Tests on the Aquia greensand at Massey and Queenstown indicate a coefficient of transmissibility of 4,100 and 35,000, respectively. Storage coefficients were 0.0005 and 0.00025, respectively. At Chestertown an aquifer test on the Aquia greensand failed to give a satisfactory result for the value of T and S due probably to indeterminate boundary conditions in the aquifer. An aquifer test in the Wicomico formation at Price showed a coefficient of transmissibility of 30,000 gpd per ft. and a storage coefficient of 0.0003.
The quality of ground water in the Coastal Plain area is generally good. The content of dissolved solids is low, and pH lies within a narrow range of the neutral point. Water from several aquifers, however, contains iron in sufficient quantity to cause trouble for the domestic user. Ground water from the Patapsco, Raritan, Magothy, Matawan, and Monmouth formations is generally rather high in iron. Water from the Matawan, Monmouth, and, in southern Queen Annes County, from the Aquia greensand, is hard. At places ground water from the Wicomico formation is soft and free of iron.
The average temperature of the ground water is approximately 58°.
Three general classes of wells are used, drilled, dug, and driven. Of the approximately 2,100 wells inventoried, drilled wells constitute about 53 percent, and dug and driven wells about 47 percent.
Fluctuations of the water table since 1949 were determined by periodic measurements in six observation wells. These showed an annual fluctuation in response to recharge to and discharge from the ground-water reservoirs caused by changes in the rate and amount of precipitation and by other factors. Fluctuation of the water level were observed in two artesian wells for a shorter period of time. No significant decline in water levels was observed. A comparison of the static water levels at Rising Sun, Massey, Millington, and Stevensville with those measured more than 40 years ago indicates no significant change in static levels in the water table or in artesian aquifers in those areas.
A rough estimate of the amount of ground water in storage in the sediments underlying the three counties is 31 trillion gallons. The amount of water recharging the deposits is about 0.4 to 0.6 million gallons per square mile per day. The present consumption of ground water is about 4,000 gallons per square mile per day, or only about 1 percent of the estimated ground-water recharge.
