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VII -6 are to the developer, the bui 1din9 owner, and to the pub! ic. The values would not be estimable without a detailed study and would be simi lar for all alternatives. 2. Reduced Street Maintenance. It ie; recognized in hi9hway engineering that poor surface drainage and hi9h ground water tables are enemies of good pavements. The same is true of urban streets. Potholes, alligators, cracks, and similar distress in pavement surfaces can often be traced to poor drianage, both surface and subsurface. Besides roads near the major drainage system, probable road con- ditions throughout the basin wi I I improve because of a clearer out- fall for the initial drainage systems" This figure is not dis- tinguishable because of the complexities and relative causes of street deterioriation. 3. ~roved Traffic Movement. A rainstorm in Denvel- often signals an early exodus from places of business by the employees because they know that traffic movement will be slow. A wet motor in one auto can stall a long line of traffic. Ponding of water on the streets and at Intersections slows traffic, and often reduces a four-lane arterial quite effectively to a two- lane street from the traffic standpoint. The Lena Gulch channel work and subsequ€mt local drainage improvements wi 11 result in much improved traffic Icovemenl: during stom runoff periods. Dollar values for this secondary benefit were not included in the evaluation of the alternatives. These benefits, however, do not vary significantly from alternative to alternative and would not significantly change our basic conclusi~,s. 4. Public Health Benefits. Public health and welfare is a prime consid- eration when evaluating the advantages and disadvantages of a good storm drainage system. The type of public health benefits include consideration of pest and insect control. Furthermore, it Is well established that storm runoff water, particularly following the initial flush-down of gutters and streets.. is rathel" highly polluted. The pol- lution consists of coliform organisms, suspended organic solids, and settleable solids. It Is evident that standing water, because of poor drainage, can have an adverse effect upon public health because of these pollutants. For all alternatives, public health wi;; be improved fairly uniformly. This type of benefit was not claimed for the same reasons elaborated upon for the improved traffic movement benefits.