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I I I I I I I I I I I I I I I I I I I discharge to Bear Canyon Creek. Surface runoff that does not enter the sewers may go to South Boulder Creek via streets draining to the West Valley Overflow routes. To simplify the model, the storm sewers are ignored and all of the discharge is assumed to go to the West Valley Overflow. This assumption does not affect flows along the major spill routes, but could affect flows on local tributaries west of Foothills. The area northwest of Foothills and Baseline is assumed to go to the Wellman and thence eastward. The area draining to the Wellman from Bear Canyon Creek to Foothills needs to be carefully analyzed. The ultimate South Boulder Creek model needs to be integrated with a Bear Canyon Creek model to determine the correct flow routing. The modeling of flows on eastbound Baseline Road at Crescent Drive (east of Foothills Parkway) is complex. The initial model assumed a one-third split of the discharge into the Crossover Ditch upstream of Crescent, one-third direct flow north to Crescent over the Crossover Ditch culvert, and one-third to the Crossover Ditch downstream of the Crescent culvert. Note that the Crossover Ditch has very limited capacity west of Crescent, and another split tests this capacity, and spills in excess of the Crossover Ditch capacity to Crescent Drive. The levee along the Wellman needs to be surveyed. The initial model used existing topography provided by the City of Boulder and very simplified hydraulics. The topography has only 2-foot contour intervals. A flow split model is needed. The discharge entering the Dry Creek Ditch No.2 syphon at 55th Street and the Wellman Ditch was routed to the ditch on the golf course. This and the spills north of the Wellman need to be routed in a more refined manner as part of future efforts. IV - 4