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Chapter 5 RESTORING AQUATIC RESOURCES TO THE LOWER MISSOURI RIVER: ISSUES AND INITIATIVES By David L. Galal, t John W. Robinson,2 and Larry W. Hesse3 INTRODUCTION Most large rivers in developed countries have been severely influenced by human alteration (petts, 1984; Davies and Walker, 1986; Hynes, 1989), and the Missouri River is no exception. Significant intervention began after the Louisiana Purchase, when in 1804, Lewis and Clark were commissioned by the Federal government to find a road to the West for economic development (Keenlyne, 1988). Subsequently, the Missouri River became the first great highway for exploitation and settlement of the Ameri- can West. The Missouri River has been so radically altered by damming, channelization, and pollution that its funda- mental aquatic character and processes no longer approxi- mate natural conditions. Our goal is to review existing information on the lower Missouri River. To accomplish this. we have four objec- tives: (I) review the theoretical framework for perceiving large river-floodplain ecosystems and natural versus human-induced disturbance, (2) briefly describe the lower Missouri River ecosystem, (3) summarize major alterations and their effects on the biota, and (4) conclude by recom- mending restoration approaches and reviewing current res- toration efforts. RIVER-FLOODPLAIN INTERACTIONS IN LARGE RIVERS Disturbance and recovery of large rivers cannot be understood without a conceptual framework of their normal behavior. Streams and rivers exist in a state of dynamic I National Biological Service, Missouri Cooperative Fish and Wildlife Research Unit. 2Missouri Department of Conservation. 3River Ecosystems. Inc. equilibrium (National Research Council, 1992). Local phys- ical features are naturally created, change through time, and eventually disappear, while the overall pattern (e.g., riffle- pool sequence, meandering) remains constant at large spa- tial and long temporal scales. This dynamic equilibrium in the physical system creates a corresponding dynamic equi- librium in the biological system. Contemporary perceptions of the structural and func- tional properties of lotic waters are largely expressed in two paradigms: the river continuum concept (RCC) (Vannote and others, 1980; Minshall and others, 1985) and the resource spiraling concept (Webster and Patten, 1979; New- bold and others, 1981; Elwood and others, 1983). The RCC says that a continuous gradient of physical conditions and resources exists from a river's headwaters to its mouth. The stream's physical features provide much of the habitat tem- plet for stream community structure and function. River net- works are viewed as longitudinally connected systems of ordered biotic assemblages. forming a temporal continuum of synchronized species replacements. Ecosystem~level pro- cesses in downstream reaches are linked to those upstream through processing inefficiencies or leakage, so that upstream energy loss becomes downstream energy gain. Consequently, there is a trade-off between maximizing nutrient and energy use within a reach via retention mecha- nisms that minimize downstream energy loss and the depen- dency on this material to drive downstream processes. Within this framework a storage-cycle-release phe- nomenon, tenned resource spiraling (rather than recycling), becomes apparent because of the unidirectional flow of water and continuous transport of materials in lotic ecosys- tems (Webster and Patten, 1979; Elwood and others, 1983). Efficiency of utilization of nutrients and organic carbon within a reach is associated with the tightness and magnitude of the spirals. Physical retention, microbial activity, and macroinvenebrate processing are important activities for defining the tightness of resource spiraling and 49