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II 1-9 The Puls method of flood routing through a reservoir (Reference 9) was used for this analysis. An example of the effects of reservoir routing for Hidden Lake and Bates Lake for the future development storm runoff conditions can be seen in Figures 111-4 and 111-7. For the future development condition, the 100 year peak flow of Hidden Lake is reduced from 2171 cfs to 326 cfs (dam overtopping) while storing a maximum of 139 A-F out of 170 A-F of storm runoff. The Bates Lake detention system reduced the future development conditions 100 year storm runoff from 466 cfs to 26 cfs while storing 17.6 A-F of the 21.0 A-F of storm runoff. The maximum 100 year water surface of Bates Lake is 0.5 feet below the existing low point of the crest, which is to be increased to three feet, according to the current Arvada plans for Bates Lake Park. There are several areas, both in the Hidden Lake Planning Basin and Bates Lake Planning Basin where storm runoff "splits" and flows in two distinct directions. This flow splitting is caused by the inability of the existing drainage facility to pass or carry the entire storm flows. In the Hidden Lake Planning Basin, three flow splitting conditions were identified, one at 66th Avenue and Lowell Boulevard, one at 64th Avenue and Lowell Boulevard and one at the D & RGW Railroad and Tennyson Street. The splitting of flows at these locations is caused by the flows backing up at the existing culverts and causing the storm water to overtop the street. The degree of flow-splitting was analyzed by estimating the percentage of area available for overflow in each direction. Based on this procedure, thirty percent of the flows at 66th and Lowell flow east along 66th Avenue and twenty percent of the flows at 64th and Lowell Boulevard flow east along 64th Avenue, as can be seen from Tables 111-4 and 111-5. The third flow splitting situation, at the "