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I I " I I I I I I I I I I I I Review the Staff Gage Rating Curves for Coal Creek An inspection of the existing staff gages was made on May 12, 1993 by the CWCB. It was discovered that the channel bed at the 1st Street Bridge had aggraded. The gage downstream of Maroon Street had been destroyed. Provide Temperature Reviews for the Years 1978. 1984. and 1993 Tables are presented for the study years, which are also displayed on a curve. By recording and plotting the 1993 values, a trend can be established for the forthcoming melting period. An increase or decrease in the slope of the curve will be immediately reflected in the future discharge for the stream. Re-evaluate and Develop a 1993 Rating Curve for the 1st Street Bridge and Maroon Street Bridge Staff Gages In May 1993, the CWCB evaluated the existing rating curves which are a depicted as stream height versus discharge. It was discovered that the existing curves are no longer representative of the channel cross sections. New curves have been developed (see V. and the attached rating curves). Potential Flooding Problems Should the 1993 Spring snowmelt runoff yield a discharge greater than 600 cis, the Town will have a flood problem which will have to be handled by alternate flow paths or increased streambank heights (see VI.). Outline a Procedure for Developing a "Flood Preparedness Plan" Upon completing an evaluation of 1) the basin snowpack, 2) capacity of the Coal Creek Channel, 3) conditions of the channel banks and levees, and 4) the runoff potential, it appears that the Town may need a "Flood Preparedness Plan" which willinc1ude the following elements: . Recording the daily "high" and "low" temperatures to determine the Degree Days; . Reading and recording the Staff gage levels to determine a daily discharge; I I . Obtaining the daily water content of the snowpack for the basin; . Developing a "Mitigation Plan" for discharges greater than 500--600 cfs; I I