Please do not destroy or throw away this publication. If you have no farther use for it write to the Geological Survey at Washington and ask for a frank to return it DEPARTMENT OF THE INTERIOR HUBERT WORK, Secretary UNITED STATES GEOLOGICAL SURVEY GEORGE OTIS SMITH, Director WATER-SUPPLY PAPER 537 A STUDY OF COASTAL GROUND WATER WITH SPECIAL REFERENCE TO CONNECTICUT BY JOHN S. BROWN Prepared in cooperation with tbe CONNECTICUT STATE GEOLOGICAL AND NATURAL HISTOET SURVEY H. H. Robinson, Superintendent WASHINGTON GOVERNMENT PRINTING OFFICE 1925 DEPARTMENT OF THE INTERIOR HUBERT WORK, Secretary UNITED STATES GEOLOGICAL SURVEY GEORGE OTIS SMITH, Director Water-Supply Paper 537 A STUDY OF COASTAL GROUND WATER WITH SPECIAL REFERENCE TO CONNECTICUT BY JOHN S. BROWN Prepared in cooperation with the CONNECTICUT STATE GEOLOGICAL AND NATURAL HISTOKY SUBVEt H. H. Robinson, Superintendent Water Resources Branch, Geological Survey, Box 3 106, Capitol Station Oklahoma Ci»y, Okla WASHINGTON GOVERNMENT PRINTING OFFICE 1025 ADDITIONAL COPIES OF THIS PUBLICATION HAY BE PBOCUEBD FROM THE SUPERINTENDENT OF DOCUMENTS OOVEBNHENT PBINTIHO OFFICE WASHINGTON, D. C. AT 2QPBNTS PER COPY CONTENTS ^Preface, by O. E, Meinzer__ __ _ _ _ :._. vn Introduction . 1 Acknowledgments. _. _ _____ _ _______________ _ _ _=... 2 Definitions. __ _ __ _ _____ ______ _ _ _ _______ _ ____ _ ____ _ ___ 2 The New Haven coast. _____ _ ____ __ ' 2 Limits __________ ___ _ __ ___ _________________ 2 Rock formations. __ _ 4 Crystalline rocks __ 4 Triassic sandstone __ _ ____ _ __ _ _ __ __ ____ _ 5 Triassic trap __ _ _________ __ __ _ 5 Glacial drift _ 5 Mud of New Haven Harbor. ____ __ ___ _______ _______ 6 Shore features. _____ _ __ ___ __ __ ____ _ 6 Late history of the Connecticut coast. _ : _____ 6 Beaches, bars, and spits. _ __ 7 Tidal marshes. __-. __ _____ ___ ____ _ _ _______ 7 Islands___ __ _ ______ 8 Ground water. _______ _____ __ ____ ____ _____ ___ _ _ 8 Source and movement of ground water ___ _ _ _ __ __ ___ 8 Occurrence in the different rocks... _ _ __ ____ 9 Development and uses of ground water___ _ ______________ _ _ _ 9 Coastal ground water ________ _ _______ __ _ _ _______ 10 The problems _ __ _ _____ _ __ _ __________________________ _ ___ 10 Methods of in vestigation____ ________ __ _______ r 11 Some results of previous investigations . __ 14 General review __ ________ _ _______________ ________ _ 14 The theory of Badon Ghyben and Herzberg _ _ 16 Relations of salt and fresh water on the coast of Holland:_ ____ : 18 Laboratory experiments applied to coastal ground water __ 18 Contamination in shallow weUs... __ _____ _ 21 Contamination in deeper wells. ___ _______ __ 25 Contamination under special topographic and geologic conditions.. _ 28 Tidal marshes.. __________ _ ______ _ _______ 28 Bar beaches and spits ____ __ __ _ 29 Islands.... _________ _ _ _ 30 Effect of fractures in bedrock.- ___ ___ . __ ______ ____ 32 Artesian conditions in New Haven Harbor ____ 33 Nature of the contact between salt and fresh ground water 34 Effects of pumping ____ ... _ ____ ... 37 Theoretical considerations. _ __ ______ ___ : 37 Data from the New Haven coast _ _ _ ___ 3& Data from Long Island- ________ _ 44 Influence of tides on ground water___ 1 - 49 Fluctuations of level due to tides __ _______ __ 49 Variations in salinity due to tides. _ 51 Seasonal variations in salinity of coastal ground water ____ : 53 Analyses of water from the New Haven coast ____ ___ 5ft Detailed descriptions of wells, springs, and pumping plants on the New Haven coast. _ ____ _ __ _ ... _ _______ _ ____ ______ 58 nr IV CONTENTS Bibliography of coastal ground water ____ * ________________ 84 United States __ _____________________________________________ 84 Hawaii. ___________._____._______________________1___________ 88 , Haiti __ ___ ____ ___ _ ___ ___________ ___ ._._ ___ _.__., 89 Antigua _______ _____ _____ ________ _ _ _____ __ __ _ 89 Great Bri.t»itt________ _________________________________________ 91 France, Belgium, Netherlands, and Germany __________________ __^ 93 Index ____________________________________________ _ ________ _ _ 99 ILLUSTRATIONS ', Page PLATE I. Map of the New Haven coast, showing the geology and the lo- ; cation of wells, springs, and pumping plants ___________ In pocket ;. II. A, Cleavage and joints in schist, Guilford, Conn.; B, Joints in gneiss, Essex, Conn_____________.___-.______________l___ 8 III. A, Section of till, Orange, Conn.; B, Section of stratified drift, Milford, Conn______________________________ 8 IV. Bea&ftea, arid sea cliifs in stratified drift; _1, Webster Point, Madison, Conn.; B, Pond Point, Milford, Conn.___________ 8 ; V. A, Bar beach, Morgan Point, East Haven, Conn.; B, Bar or tombolo, tying Charles Island to mainland, Milford, Conn_._ 8 VI. A, Water hole yielding fresh water on the beach of a small island near Cedar Keys, Fla.; B, House of Robert Mitchell, south­ west of Guilford, Conn____---_----_--_--_--___---___-___ 24 VII. A, Plant of New Haven Gas Light Co., New Haven, Conn.; B, View of New Haven, Conn., from East Rock, showing salt marshes of Mill River-___-_-___--_-_--_-_----_-----__-_- 24 FIGURE 1. Map of Connecticut showing physiographic provinces, bed­ rock geology, and area covered by this report____________ 3 2. Section of; thes island of Norderney, Germany, showing the application of Herzberg's theory---_--___---_-_-----_--- 17 3. Relations between salt and fresh water on the Holland coast-- 19 4. Map of Cedar Keys, Fla., showing location of wells sampled,- 24 5. Sketch map of vicinity o£ well 152, west of Clinton, Conn., showing relation of well to tidal marsh_-__________-_--___ 29 6. Sketch map of Mulberry Point, Guilford, Conn., showing bed­ rock structure near well 125______---__-_-_-_---__-____- 32 7. Section illustrating artesian conditions in New Haven Harbor, Conn__________________-----_-________ 33 8. Ideal diagram showing movements of fresh ground water and gradation into sea water along shores composed of uniformly porous sand: A, On a small island; B, on a mainland ; shore______-______________-___-_--___-_---__-----_-_- 35 9. Modifications of the contact between salt and fresh ground water due to impervious beds_________________________ 36 10. Cone of salt water induced by pumping overlying fresh water. _ 38 11. Section illustrating contamination in wells orf filled land in New Haven, Conn______________---__-_-____-_-----_-- 42 12. Map of a part of the water front, New Haven, Conn., showing location of plant of Sargent & Co_______________________ 42 CONTENTS V £ ** FIGURE 13. Sketch map showing location of well groups of American Steel & Wire Co. -and Penn Seaboard Steel Corporation, New Haven, Conn_____________________________________-___ 43 14. Outline map of western Long Island, showing pumping plants bearing on contamination by,sea,,water_ __________________ 44 15. Salinity of water in the *Ridgewood ctdlgctfngf system; ;i|ear ^ ; Brooklyn, N. Y., and comparison with jfteld and rainfall. _^ 46 16. Comparison of pumpage and salinity at Shetucket pumping station, near Brooklyn, N. Y_______________________-___ 47 17. Head of fresh ground water necessary to exclude sea water of any specific gravity from wells of different depths.._______ 49 18. Well and tide curves at Oyster Bay, N. Y., showing tidal fluctuations due to plastic deformation.__________________ 51 19. Relation between tidal fluctuations and salinity of water at Spring Creek pumping station, near Brooklyn, N. Y.__.__. 52 20. Relation of salinity to temperature and rainfall in Peter Beattie well in Branford Township, Conn________________ 54 PREFACE By O. E. MEINZEE The sea coasts of the United States, exclusive of Alaska and the island possessions, have a total length of 4,883 miles, measured in 3 NBaate*«gte^; ;and 21,862 miles, measured in 1-mile steps.1 These coasts are of special importance with respect to commerce, recreation, and national defense and are, on the whole, belts of intensive human activity. Because of this activity a considerable number of large water supplies and very many small water supplies are required, but the proximity of salt water makes it difficult, at many places along the coasts, to obtain supplies of good quality. Hence numerous inquiries are received by the Geological Survey as to the prospects of;-ob'tjainiog, fresh water fiom wells sunk near the sea. The need for a comprehensive paper on this subject has long been felt by those concerned with problems of water supply. The pres­ ent paper largely meets this need. Though limited in time and facilities for his investigation, Mr. Brown has obtained very sub­ stantial results. His field work was done chiefly on the coast of Connecticut, but he has also had opportunity to study some of the keys along the Florida coast. He has added greatly to the value of his paper by presenting data from many sources on coastal ground water in the United States and by digesting the valuable but rela­ tively inaccessible foreign literature on the subject. He has very successfully correlated the data obtained Jby other investigators with his own data and has applied the results effectively to the problems of water supplies on the coasts of this country. The subject is complex. The great variety in climate, topography, starftt^itp^y,' and rock structure along the seacoasts has resulted in a coirespontting variety and complexity in the relations of the sea water to the ground water. Moreover, these relations vary with the depth below the surface, chiefly because of the difference in specific gravity of fresh and salt water, and they may be totally altered by heavy pumping.