REPORT OF INVESTIGATION 54 Potential Surface Water Reservoirs of South-Central Illinois by JULIUS H. DAWES and MICHAEL L TERSTRIEP Printed by authority of the State of Illinois—Ch. 127, IBS, Par. 58.29 STATE OF ILLINOIS HON. OTTO KERNER, Governor DEPARTMENT OF REGISTRATION AND EDUCATION JOHN C. WATSON, Director BOARD OF NATURAL RESOURCES AND CONSERVATION JOHN C. WATSON, Chairman ROGER ADAMS, Ph.D., D.Sc, LL.D., Chemistry ROBERT H. ANDERSON, B.S., Engineering THOMAS PARK, Ph.D., Biology CHARLES E. OLMSTED, Ph.D., Botany LAURENCE L. SLOSS, Ph.D., Geology WILLIAM L. EVERITT, E.E., Ph.D., University of Illinois DELYTE W. MORRIS, Ph.D., President, Southern Illinois University STATE WATER SURVEY DIVISION William C. Ackermann, Chief URBANA 1966 FOREWORD In many parts of Illinois, reservoir storage of water is an important means of increasing usable water supplies to enable community growth and development. Because of this significance for water resources of the future, the Illinois State Water Survey initiated a reconnaissance investigation to identify potential sites within the state where surface storage of water is physically feasible. This report provides information on potential and existing reservoirs in 29 counties of south-central Illinois. Results of an earlier study of possible sites in the 17 southern counties of Illinois were published in 1957 as Report of Investi­ gation 31. Future reports will include similar information for 33 north-central counties and 23 northern counties. This division of the state was based primarily on drainage systems. These publications are intended to bring about greater understanding of the surface water storage potential. It is hoped that the information will be of value in rural, urban, and regional planning for development of industry, agriculture, and recreation. CONTENTS PAGE Summary 1 Introduction 1 Objectives and scope 1 Acknowledgments 2 Part 1. Hydrology 3 Study criteria and procedures 3 Climatological elements 4 Precipitation 4 Snowfall 6 Cold air and soil temperatures 6 Geology 7 Streamflow and water yields 9 Municipal surface water supplies 12 Eeferences 13 Part 2. Potential reservoir sites 14 Bond County 15 Calhoun County 18 Clark County 21 Clay County 26 Clinton County 30 Coles County 32 Crawford County 36 Cumberland County 39 Douglas County 44 Edgar County 45 Edwards County 48 Effingham County 50 Fayette County 53 Greene County 57 Jasper County 62 Jersey County 65 Lawrence County 70 Macoupin County 72 Madison County 80 Marion County 85 Monroe County 90 Montgomery County 94 Moultrie County 9S Richland County 101 Shelby County 104 St. Clair County 107 Wabash County 112 Washington County 112 Wayne County 117 ILLUSTRATIONS FIGURE PAGE 1 Capacity-watershed area criteria extracted from sedimentation curves 3 2 Average annual precipitation, in inches, 1900-1944 period 5 3 Average colder half-year precipitation, in inches, 1900-1944 period 5 4 Average warmer half-year precipitation, in inches, 1900-1944 period 5 5 Maximum rainfall amounts equalled or exceeded for various recurrence intervals and durations at any point in south-central area 6 6 Areal frequency distribution of maximum 24-hour amounts equalled or exceeded at various recurrence intervals in the south-central area 6 7 Minimum 6-month precipitation amounts, in inches, expected once every 5 and every 25 years, for colder and warmer half-years 7 8 Minimum 24- and 60-month precipitation amounts, in inches, expected at varying recurrence intervals 8 9 Average annual snowfall, in inches, 1920-1955 period 9 10 Stream gaging stations and numbers 10 PLATE 1 Surface water resources of south-central Illinois In pocket TABLES TABLE PAGE 1 Average number of days with varying weather conditions per month 6 2 Summary of discharge records at stream gaging stations 11 3 Data on public surface water supplies 12 Potential Surface Water Reservoirs of South-Central Illinois by Julius H. Dawes and Michael L Terstriep SUMMARY The south-central portion of Illinois comprises 29 counties having a total area of 14,586 square miles. The physical potential for development of surface water reservoirs is favorable in much of this area because the rainfall and the resulting runoff is adequate and the topography is suitable for reservoir construction. The counties included in the south-central section are Bond, Calhoun, Clark, Clay, Clin­ ton, Coles, Crawford, Cumberland, Douglas, Edgar, Edwards, Effingham, Fayette, Greene, Jasper, Jersey, Lawrence, Macoupin, Madison, Marion, Monroe, Montgomery, Moultrie, Richland, Shelby, St. Clair, Wabash, Washington, and Wayne. Within these counties 218 potential surface water reservoir sites have been identified. Potential sites are abundant in Clark, Coles, Cumberland, Greene, Jasper, Macoupin, Mad­ ison, Marion, and St. Clair Counties. Sites suitable for reservoir development are scarce in Calhoun, Clinton, Douglas, Edgar, Edwards, Lawrence, Moultrie, Wabash, and Wayne Counties because of unfavorable to­ pography or geology, or both. Calhoun County had a limited number of sites because of the high gradient streams with little or no watershed drainage area. Rainfall in the area averages 39.4 inches per year. Thunderstorms account for 40 to 50 percent of the annual rainfall and 65 percent of the summer rainfall. This predominance of variable convective summer rainfall causes the streamflow to be highly variable. In the warmer half-year, rainfall of less than 13 inches may be experienced once in 5 years. Ground-water contribution to streamflow causes continuous flow in many of the streams on which potential reservoir sites have been located. The normal runoff from an average rainfall of 27.4 billion gallons per day (bgd) is estimated at 7.15 bgd from 14,586 square miles of drainage area. An average 5.55 bgd flows from the 29 south-central counties via the Kaskaskia River, the Little Wabash River, the Embarras River, and tributaries to the Mississippi, Illinois, and Wabash Rivers. INTRODUCTION It is becoming increasingly apparent that water sup­ skia River near Shelbyville in Shelby County. It will ply deficiencies can exist in the 29 counties described as control 1030 square miles and have a total storage capa­ south-central Illinois. This region is bordered on two city of 684,000 acre-feet. Lincoln Reservoir, located on sides by major rivers, the Mississippi on the west and the Embarras River near the Coles-Cumberland County the "Wabash on the east. Internally the area is drained line, is in the planning stage and when completed will by Macoupin Creek, the Kaskaskia River, the Little control 915 square miles and have a total storage of Wabash River, and the Embarras River. There are 538,300 acre-feet. All three reservoirs have three pur­ several developments of surface water impoundments, poses, flood control, water supply, and recreation. exemplified by the following lakes: Johnsonville, Lincoln There are over 218 potential reservoir sites capable of Trail State Park, Mattoon, Charleston, Sara, Collins- development within the 29 counties. This section of the ville, Horseshoe, Silver, Raccoon, Omega, Moredock, state supports a population of 1,026,000, or 21 percent Hillsboro, Washington County, and New Gillespie of the total state population, and extends over 14,586 Reservoir. square miles which represents 26 percent of the area Three large reservoirs are in progress by the U.S. of Illinois. Army Corps of Engineers for this area. Carlyle Reser­ voir on the Kaskaskia River near Carlyle in Clinton County is now under construction and almost completed. Objectives and Scope After completion of the dam in early 1966, filling is expected to take two years. The reservoir controls 2680 This report is primarily an inventory of potential square miles of drainage area and has a total storage reservoir sites, plus a partial list of presently developed capacity of 983,000 acre-feet. Initial construction phases sites, for the 29 south-central counties. The sites are have begun for the Shelbyville Reservoir on the Kaska­ potential reservoir areas insofar as they have 1) the 1 physical characteristics necessary to impound water, Since the basic site data were obtained from topographic 2) runoff from the watershed in sufficient quantities to maps, they may require modification in light of addi­ provide storage for beneficial use plus anticipated losses, tional field investigations. and 3) relative freedom from man-made or natural ob­ This report has two principal parts. Part 1 discusses structions. Although a large potential for reservoir the pertinent hydrologic elements including geology storage is present in the south-central counties, the dis­ and climate. Part 2 includes the data on potential and tribution over the area is poor. existing reservoirs for each of the 29 counties. A complete evaluation of the potential reservoir sites for water resource development involves far more than physical availability of sites such as considered here. It Acknowledgments is important to consider water developments in relation to other natural resources, social and political environ­ This study has been completed by the authors under ment, and the economy of a region. Cost of development the guidance of H. F. Smith, Head of the Hydrology must be balanced by benefits. These are all critical fac­ Section, and William C. Ackermann, Chief, Illinois tors that must be dealt with before a comprehensive State Water Survey. A number of Water Survey per­ report can be made. The surface water impoundment sonnel have aided in the preparation of this report. John potential is dependent upon rainfall, topography, run­ B. Stall, Engineer, provided the streamflow analysis off, geology, and man's occupancy as determined from and furnished counsel during the development of a com­ an analysis of physiographic and hydrographic data. puter program used in watershed yield analysis. W. J. This inventory of potential reservoir sites was selected Roberts, Engineer, made available previous reservoir from a map study of U. S. Geological Survey quad­ studies and evaporation data.