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. . . . At this point in the analysis there are five regions in the Arkansas basin. Region 1 includes the southern foothills. Region 2 includes the central foothills. Region 3 includes the mountains. Region 4 includes the northern foothills (Colorado Springs area). Region 5 includes the eastern plains. Because there were so many data points in the Colorado Springs area and because Region 4 is subject to a great deal of internal hydrologic variability, Region 4 was subdivided into 4 sub- regions (4a, 4b, 4c, 4d). There are, therefore, 8 preliminary regression equations to address all of the approximate stream reaches in the Arkansas River basin. The preliminary equations and curves for the Arkansas basin were presented to the Hydrology Advisory Committee for comment The approval of the methodology was given provided the limitations and disclaimers are identified. The only adjustment recommended by the committee was the selection of less complex equations. In those cases where it was appropriate a less complex equation was selected. What About Stream Gal!:e Data? The Hydrology Advisory Committee included representatives of the USGS. They asked why the Guidelines were based on previously designated studies which might have been prepared by a variety of methodologies. Instead they suggested that regional regressions already prepared by the USGS using stream gage records throughout the state could be used. In 1976 just such a publication was prepared. The Board's TM-I publication, prepared in cooperation with the United States Geological Survey has been useful in many hydrologic analyses. TM-I presents regional regression curves which were developed from stream gage data. Over the past 20 years, it has been discovered that the methods presented in the manual may over-estimate the IOO-year floodplain values in some regions and under-estimate the values in other regions. More recent USGS publications have updated some of the TM-I analyses for specific regions of Colorado. There is still some disagreement among hydrologists about the suggestion that gage analyses should always take precedence over other forms of hydrologic analysis. The Hydrology Advisory Committee debated this issue and decided to support the Board staff position that already designated data should form the basis of the guidelines. The Board staff and the committee recommend, however, that the differences between gage analyses and other hydrologic analyses ought to be investigated on a continuous basis, particularly in foothills regions of Colorado where the gage network is not as comprehensive as it should be. The answers to the questions about gage data are not cast in stone, Remaininl!: Work In addition to the work already performed in the Arkansas River basin, initial work has begun on the South Platte River basin (including the Republican River basin). Most of the data points in the South Platte basin have been entered into the spreadsheet. No subdivision of the basin into regions has been performed. For the other major basins (Colorado River, San Juan River, Rio Grande and Green River) no data collection has been done. Because the South Platte basin includes over half of the current flood hydrology data points in the state, that analysis is expected to take some time. Once the South Platte analyses have been completed, the CWCS