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001181 PART n: CASE HISTORIES OF MULTJ.GOVERNMENT FLOODPLAIN MANAGEMENT Introduction The case studies which follow illus- trate a variety of problems and ap- proaches in the management of flood- plains by multiple governments. The studies concern small urbanizing water- sheds located in six diverse regions and states: Mississippi, Oitlahoma, illinois, Tennessee, Minnesota, and Massachu. setts. While the nature of the flood prob- lem, the extent of urban development, and the laws and customs of each area differ, there is much of value to be learned from each case history which may be applied elsewhere in the U.S. The first two cases-the Pearl River in Mississippi and Haikey Creek in Okla- homa-depict "horror stories" of the re- sults of lack of intergovernmental plan- ning and coordination in floodplains. While each is complex in its facts, the Pearl River case involves principally a conflict between cross-stream jurisdic- tions while Haikey Creek presents upstream-downstream issues. The next four cases illustrate various approaches to multi-governmental coor- dination, with differing degrees of suc- cess. In the Salt Creek case, a county forest preserve district served as catalyst to an intercommunity floodplain acquisi- tion program. Maryville and Alcoa, Ten- nessee, under the benevolent encourage- ment of TV A agreed to coordinate their floodplain policies through an intergov- ernmental agreement. Lilydale, Minne- sota, was relieved of a chronic flood problem through extraterritorial action by Ramsey County which acquired the Lilydale floodplain and relocated its resi- dents. Finally, the Charles River case indicates the opportunities for coordi- nating federal, state, and local actions- both structural and nonstructural-to relieve flooding on a basinwide basis. 1. JACKSON, MISSISSIPPI-PERIL ON THE PEARL Thi3 is the story of wishful thinking in .Juckson, Mississippi-by the local authorities, the local citizens, and the federal government-all of whom ignored the possibility of disaster until it struck on Easter, 1979. The Setting: At the River's Edge The Pearl River rises in central Mi81lis- sippi and flows south for 240 miles until it reaches the Gulf of Mexico at the boundary between Mississippi and Lou- isiana. Its watershed is about 8,760 square miles-usually drained in a lei- surely fashion, for the Pearl is in most places, at most times, a shallow, meander- ing stream' (average gradient, approxi- mately one foot per mile). About halfway down the Pearl-with 3,110 square miles of drainage area above it-lies Mississippi's capital city, Jackson, on the west bank of the river. The natural floodplain at Jackson is around two miles wide, through which the Pearl plods sluggishly. However, neither the floodplain nor the river's course are still natural there: the ROBS Barnett Dam just upstream, extensive channelization, and levees on the east and west banks (all constructed during the 1960's) have caused subltantial river- ine changes. Nor has the city and its environs stayed the same. Between 1960 and 1976, Jackson grew from 144,422 to 205,100 in population (partly through annexation). Across the river, the city of Pearl's population has more than tripled, going from 5,081 in 1960 to 15,750 in 1976 (although the small town of Flowood has largely held to its 1960 level of 500 due to a lack of bridge ac- cess to Jackson. In addition, the wholly new city of Richland with a population of more than 3,000 has grown up on the east bank since 1960 (Fig. 13). Why all this growth? To some extent, it can be attributed to normal popula- tion change, but it is also due to other 27