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sus years from 1944-1974. Crop and Livestock Re- porting Service livestock estimates were used for the years 1975-1978 if they were available. The county- level estimates of livestock numbers were aggregated to the various node hasins. It was assumed for distri- bution between node basins that livestock would be uniformly distributed throughout each county. Surface water depletions due to four separate land treatment practices, and farm ponds were estimated. These practices were: (1) contour farming, (2) ter- races, (3) minimum tillage, and (4) range pitting. De- pletions from farm ponds with fewer then 40 acres in surface area were also considered. As indicated earlier, data were collected at the county level and aggregated by node basin. It was assumed that land conservation practices and farm ponds were uniformly distributed throughout each county and distributed to node basins on that basis. Information available from the aggre- gate data includes total node drainage area, acreage total for each land conservation practice, and per- centage area affected by county by node for all nodes in the basin. A time distribution curve was developed for the base years 1944, 1950, 1960, 1970, and 1978. This distribution was used for determining acreages and depletions for all years. Estimates for intervening years were determined by assuming a constant rate of change between base years. Yearly depletion estimates were made for average weather conditions and dis- tributed on a monthly basis. A single monthly deple- tion distribution was used for the entire basin. Approximately 27 million acres or eight percent of the Missouri River basin is forested. Approximately ]6 million acres are located in the Rocky Mountains with the remainder primarily located in the Black Hills, Ozark High]ands, and along streams. These for- ests, particularly in the Rocky Mountains, are more important from a hydrological standpoint than their relative]y limited extent would imply. Mountain for- ests usually occur in areas which experience heavy accumulations of snow. Runoff from many such for- ests exceeds one acre-feet per acre per year compared to less than one inch of runoff occurring annually over most of the Great Plains portion of the basin. Forest management practices affect water yields in two prin- ciple ways: through snow distribution and on-site eva- 20 potranspiration changes. These influences are such that they can increase water yield from forested Wa- tersheds to a level in excess of that from virgin-forest conditions. Forest Service regions covering Montana, Wyo- ming, and Colorado provided information on water yield resulting from forest management practices in those aTeas. In the remaining basin states, the water yield increased from forest management is relatively minor and short-lived: therefore, the effects On streamflow would probably not be measurable. Twenty-two node basins were selected for detailed analysis of forest water yield accretions. Tbe historical data used were collected by administrative unit for the National Forest and by county for state and private lands. These data were allocated to node basins using a proportional area method. Details on the methods used to develop these effects are shown in the work group technical paper. Municipal. Industrial, Energ)'. and Rural Domestic Water Use - Data collection and analysis of water usage for purposes other than agriculture were con. dueted within four hasic categories: municipal water use for cities with populations above 2,500, self-sup- plied industrial water use, energy water use, ana rural domestic water use. Data were collected for the 93 selected drainage areas for five record years: 1944, 1950,1960,1970 and 1978. The first step in disaggregating this data was to breakdown the data into an annual record of water use. This was done by dividing the difference between subsequent record year water use into t.he number of years hetween record years. The second step in the process was to further breakdown the annual con- sumptive use figures into monthly figures. This was done by dividing the annual total consumptive use by a monthly distribution factor. Two distributions were developed, one for energy and industrial use and an- other for municipal and rural domestic water use. For this study, for these four categories of water use, the data were collected and compiled by state person- nel. While sources used varied from state to state mu- nicipal water use records and state permitting records were the major data sources.