MA' J964 Ground-Water Resources of North-Central Connecticut GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1752 Prepared in cooperation with the Connecticut ff^ater Resources Commission Ground-Water Resources of North-Central Connecticut By ROBERT V. CUSHMAN GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1752 Prepared in cooperation with the Connecticut Water Resources Commission UNITED STATES GOVERNMENT PRINTING-OFFICE, WASHINGTON : 1964 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY Thomas B. Nolan, Director The U.S. Geological Survey Library has cataloged this publication as follows; Cushman, Robert Vittum, 1916- Ground-water resources of north-central Connecticut. Washington, U.S. Govt. Print. Off., 1963. v, 97 p. maps (part col.) diagrs., tables. 24 cm. (U.S. Geological Survey. Water-supply paper 1752) Part of illustrative matter fold, in pocket. Prepared in cooperation with the Connecticut Water1 Resources Commission. Bibliography: p. 91-93. (Continued on next card) Cushman, Robert Vittum, 1916- Ground-water resources of north-central Connecticut. 1963. (Card 2) 1. Water, Underground Connecticut. 2. Water-supply Connecti­ cut. 3. Geology Connecticut. 4. Water Composition. I. Connecti­ cut. Water Resources Commission. (Series) For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.G. 20402 CONTENTS Pag* Abstract_____________________________________________________ 1 Introduction..____________________________________________________ 3 Location and general features of the area...______________________ 3 Purpose of the investigation____________________________________ 4 Methods of study and scope of investigation ______________________ 5 Previous ground-water and geologic investigations _________________ 6 Acknowledgments. __________________________________________ 8 Well-numbering system ________________________________________ 10 Topography ______________________________________________________ 11 Streams-_______________________________________________________ 12 Climate-_________________________________________________________ 14 Physiographic development_________________________________________ 16 Pre-Pleistocene history.________________________________________ 17 Pleistocene glaciation__________________________________________ 18 Post-Pleistocene history ______________________________________ 21 Geology.__ _ ____________________________________________________ 21 Descriptions and water-bearing properties of the geologic formations. 21 Consolidated rocks_______________________________________ 22 Crystalline rocks of pre-Triassic age____________________ 22 General character and extent______________________ 22 Water-bearing properties ___________________________ 26 Yields of wells. __ ______________________ 27 Sedimentary rocks of Triassic age______________________ 28 General character and extent___________________ 28 Water-bearing properties___-___-__-___--__-______ 31 Factors causing areal variation in yield_____________ 35 Igneous rocks of Triassic age__________________________ 37 General character and extent_____________________ 37 Water-bearing properties.________________________ 38 Well construction________________________________ 39 Unconsolidated deposits____________________________________ 40 Ground-moraine deposits_________________________-___-_ 40 General character and extent______________________ 40 Water-bearing properties____-____________-_______ 43 Ice-contact deposits__________________________________ 44 General character and extent___________________ 44 Water-bearing properties____--_-____-------__-__-_- 46 Ice-contact deposits in Glastonbury, Manchester, and Vernon_________________________________________ 47 Ice-contact deposits in South Windsor and East Wind­ sor_____________________________ 48 Ice-contact deposits in Ellington and Somers______-- 49 in IV CONTENTS Geology Continued Descriptions and water-bearing properties of the geologic formations Con­ tinued Unconsolidated deposits Continued Page Outwash-plain, valley-train, and undifferentiated outwash deposits..--.-______________________________________ 50 General character and extent______________________ 51 Water-bearing properties___________________________ 53 Buried outwash deposits in the preglacial channel of the Connecticut River_____-_-_-_-_--_-_-_-_-_---___-___- 54 General character and extent______________________ 54 Water-bearing properties___________________________ 55 Glaciolacustrine and associated delta deposits_____________ 56 General character and extent of the glaciolacustrine deposits______________________________________ 56 Water-bearing properties of the glaciolacustrine deposits, 58 General character and extent of the deltaic deposits 5$ Water-bearing properties of the deltaic deposits_______ 60 Flood-plain deposits----------------------------------- 60 Dune deposits_______________________________________ 6^ Swamp deposits.-__-----_------_-------------------_-- 6l Ground water____________________________________________________ 62 General principles__-_______-_______--___-_-__---__---_-_---_-_ 62 Ground water in upland areas_______--_______-_____-_-__---___ 64 Till-mantled bedrock______________________.-._ 64 Shape and slope of the water table. ______-______--_-_-_ 64 Depth to water_____________________________________ 64 Recharge, movement, and discharge.____________________ 65 Ground water in lowland and valley areas. _______-----_-___-- _ 66 Tracts of outwash deposits_ ____________________________ 66 Shape and slope of the water table___-__--_-------------_ 66 Depth to water_____________________________________ 67 Recharge, movement, and discharge _____________________ 67 Buried outwash deposits in the preglacial channel of the Con­ necticut River____________________-___-_-_--_-_---_-__-- 68 Hydrostatic head________________-_-_-____-_-----_-__ 68 Recharge, movement, and discharge--------------------- 69 Glaciolacustrine and associated delta deposits_-___--_---_-__-_ 69 Shape and slope of the water table ___________________ 70 Depth to water___________________- ____--___-_---_- 70 Recharge, movement, and discharge.____-____----_-_____ 70 Fluctuations and trends of water levels---____-___-_-----_-------- 71 Quality of water___________________________ ________________ 73 Chemical constituents in relation to use..____________________ 78 Dissolved solids--------------------------------- --- 78 Hardness-____-________--__---_----------------------- 79 Iron. _____---____-________-_------_---------------_ 80 Chloride -_-.___------------------------------ 80 Hydrogen-ion concentration (pH) ___________________ 80 Minor constituents------------------------------------ 81 Water for irrigation__-_-___--_----__-------__---------- 81 CONTENTS Ground water Continued Quality of water Continued Types of water_____________.______________________________ 81 Quality in relation to water-bearing formations.____---__----__ 82" Pre-Triassic crystalline rocks__________________________ 82 Triassic sedimentary rocks____________________________ 82 Triassic basalt_-_----_-_-_-------__--_-_-------------- 83 Ground-moraine deposits.____________________________ 84 Ice-contact, valley-train, and outwash-plain deposits. ______ 84 Lacustrine and associated delta deposits.____-___-_-_---__ 84 Buried outwash deposits________________________ _____ 84 Utilization of ground water____-__--_-___-_______-__-_-_-------- 85 Public water supplies._____________________________________ 85 Industrial supplies.---.------------------------------------ 86 Domestic and stock supplies-------------------------------- 87 Irrigation supplies._____-______---__-__-__-_-___-__-_----__ 87 Future development of ground water_______________________________ 87 References cited.__________________________________________________ 91 ndex____________________________________________________________ 95 ILLUSTRATIONS [Plates are in pocket] PLATE 1. Map of north-central Connecticut showing generalized geology and well locations. 2. Map of north-central Connecticut showing contours on the bedrock surface. 3. Geologic sections. Page FIGURE 1. Index map of Connecticut showing area of report.___________ 3 2. Cumulative frequency curves of yield of wells___-___________ 34 3. Hydrographs of water levels. ________________ _______ 72 4. Graph showing typical chemical character of water__________ 74 5. Water-analysis diagram showing chemical character of water__ 75 TABLES Page TABLE 1. Summary of streamflow data in north-central Connecticut...- 13 2. Summary of meteorological data at Hartford ___________ 15 3. Stratigraphic units in north-central Connecticut and their water-bearing properties______________________________ 24 4. Chemical analyses of water from typical wells -__-___---__ 76 GROUND-WATER RESOURCES OF NORTH-CENTRAL CONNECTICUT By EGBERT V. CUSHMAN ABSTRACT The term "north-central Connecticut" in this report refers to an area of ahout 640 square miles within the central lowland of the Connecticut River basin north of Middletown. The area is mostly a broad valley floor underlain by unconsolidated deposits of Pleistocene and Recent age which mantle an erosional surface formed on consolidated rocks of pre-Triassic and Triassic age. The mean annual precipitation at Hartford, near the center of the area, is 42.83 inches and is uniformly distributed throughout the year. .The average annual stream- flow from the area is about 22 inches or about half the precipitation. The consolidated water-bearing formations are crystalline rocks of pre-