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NOTES: Above thet mean hi ~h waterline of bank slopes and in backwater areas~ the major soil erosive action result:; from the mechanical disintegration of soil masses by alternate wetting and dryIng (periods of precipitation and sunshine> and wind. Grasses have proven to be excel lent deterren1s to so; I erosion under these conditions. Of all the bank protection methods, vegetc:tlon Is the only self-renewable method and in many cases the most economical and aesthenically pleasing. COSTS: $5-7/bank-foot of protection. The cost of planting grass ranges from $500 to $650 per acre, including soil preparation and fertilIzer. If woody vegetation is planted with the grass, the average cosu is approximately three times that of grass alone. MAINTENANCE REQUIREMENTS: Little. ENVIRONMENTAL ASPECT: Pro,ably the least expensive, most visually attractive, and least comp J ex method of combatt I ng bank eros f on I s to estab 11 sh and ma I nta I n a deep-rooted vegetative cover along thE river. Trees provide the greatest protection against erosion because of the massive roe.t systems. Grasses and herbaceous species are also valuable, but provide less protection because their root systems are less extensive. Grasses~ however~ can be established roore quickly and at less cost than trees. Tree planting programs, and other effor1s to establish a protective vegetative cover can also provide expanded wildlife habitat, enhanced recreation opportunities~ improved aesthetics, and Improved water quality. Used alone~ vegetation Is a very positive method of erosion control. Revegetation should also be used to supplement and Improve the impacts of all of the erosion control methods which have been discussed in this section. Thought should be given to selection of plant species which wi II provide maximum erosIon protection, the most benefits to wi ldl Ife, and have the least impact on existing vegetation. 24