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by snow melt, rather than the HEC-l results obtained by modeling rainfall-runoff characteristics. The u.s. Army Corps of Engineers (USACE) HEC-1 model was used to develop peak discharges for II~inois and Jones Gulches. Peak discharge-drainage area relationships for Blue River Middle Branch and Cucumber, Illinois, and Jones Gulches are shown in Table 1, "Summar.y of Dischar.ges." The hydraulic analyses for Blue River Middle Branch and Cucumber, Illinois, and Jones Gulches were computed using the USACE HEC-2 computer program (Reference 7). starting water-surface elevation~ were determined by the slope-area method or predetermined ~ elevations. cross-section and geometric data, such as culvert sizes, inverts, bridge dimensions, and roadway elevations, were obtained from a variety of sources. Information from the original Flood Insurance Study for the Town of Breckenridge (Reference 12) served as a base. Additionally, cross sections were surveyed specifically for this restudy, particularly in areas where the topography was known to have changed. Restudies of the flood plain had been conducted for recent developments in the Town of Breckenridge. Several short sections of river had been surveyed for. projects such as pipeline crossings or new bridge construction. This information was also incorporated into the restudy. Finally, the 1980 Breckenridge Town Topographic Mapping was used in areas where it was known that conditions changed between the time of the original study and production of the Breckenridge Town Topographic Mapping. To determine channel and over.bank roughness coefficients (Manning's "n" values), an assessment of the conditions along each channel was made. In areas where channel alterations had not been made, the general, main channel "n" values ranged between 0.0035 and O.DOSO. Overbank "n" values ranged from 0.0350 to 0.1000. As part of this revision, the format of the map panels has changed. Previously, flood-hazard information was shown on both the Flood Insurance Rate Map and Flood Boundary and Floodway Map. In the new format, all base flood elevations, cross sections, zone designations, and flood plain and tloodway boundary delineations are shown on the Flood Insurance Rate Map and the Flood Boundary and Floodway Map has been eliminated. Some of the flood insurance zone designations were changed to reflect the new format. Areas previously shown as numbered Zone A were changed to Zone AE. Areas previously shown as Zone B were changed to Zone X (shaded) Areas previously shown as Zone C were changed to Zone X (unshaded). In addition, all Flood Insurance Zone Data Tables were removed from the Flood Insurance Study report and all zone designations and reach determinations were removed from the profile panels. The Flood Insurance Study for the unincorporated areas of Summit county, Colorado (Reference 13), is being updated concurrently with this restudy. These studies are in agreement with each other. Table 2, "Floodway Data," and Exhibit 1, "Flood Profiles," were revised to reflect changes as a result of the restudy. 20