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iJ. 3. ilREY EHGINEERS REPORT (CONI' 'D) the barrier. By reason of its extreme length and large capacity spillways, Cherry Creek Dam No.1 is expensive. Its cost. estilnated by the District Engineer of :',6,409,938, becomes more nearly (;8,200,000 as revised by the Board of Engineers. The reservoir design flood, as used by the Engineer Corps, if it occurred, would cause a flood of 68,300 acre-feet in volume and 166,000 sec. ft. peak discharge, unless as proposed it be controlled by Cherry Creek Dam and Reservoir No.1; would overtop and destroy the exist- ing Sullivan Barrier; and, with the failure of that structure, would create a crest flow in Denver of 230,000 sec. ft. Suoh a flood, being 11.5 times the size of the greatest flov! previously experienced. would cause enormous damages, estimated by the District Engineer, at (;40,000,000 at present valuations, or an average of ::,50,000,000 over the economic life of the structures recommended for construction. In spite of such large expenditures for flood control,- :,:10,500,000 to control 386 sq. mi. equals $27,200 per square-mile, or ::.i42.50 per acre of drainage area, - the City of Denver cannot be said even then to be fully protected from floods in Cherry Creek. If the reservoir design flood can happen above Sullivan Barrier, it can happen below. Dbile the uncontrolled area belovl is small (29-square miles), a flood from that area, at peak flow rates assumed for the area above, would exceed channel cap~city in Denver, and cause substantial damage. Similarly, it may be noted, that if the assumed design storm should visit the City of Denver, it would cause runoff greatly in excess of storm S~1er capacities, and would directly, before it reached -26- ....-