The surface and ground water resources of a 991 square mile area comprising the drainage basins of English River, Old Mans Creek and Clear Creek are presented. These basins lie to the west and southwest of Iowa City, Iowa, and all three streams are tributary to the Iowa River. The area is comprised of rolling uplands with relatively broad valleys and is devoted mainly to agriculture and livestock farming.
In general, the surface water use is adversely affected by the high variability of flows and particularly by the critically small minimum flows. Augmentation of the minimum flows by means of storage reservoirs is possible but may be uneconomical in the broad valleys which require a high area to volume ratio.
The surface water supply is presented in the form of tables and graphs which show information on maximum and minimum flows, mean flow, duration of flow, frequency of low flow and flood flow and storage requirements. Low-flow discharge. profiles for the English River and South Fork English River derived from measurements at partial record and supplementary sites are also shown.
Ground water is available from shallow wells in nearly all of the area; however, the wells vary widely in productivity and reliability during a drouth. Potentially excellent aquifers may be found in the alluvium which underlies the valleys since similar areas along the lower Iowa River basin have produced yield up to 100 gallons per minute. However, the best and most reliable source of good ground water is the Jordan Sandstone. This aquifer varies from 1,375 feet below ground level in the eastern part of the area to 2,200 feet below ground level at the western end of the area. It is capable of supplying as much as 1,000 gallons per minute to individual wells. Its location is shown in the report by means of map contours referenced to mean sea level.
