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I- I I I I I I I I I I I I I I I I I I required by the Julesberg Irrigation District for the use of their structure. The typical charge runs around $5 per acre-foot based on other users who have agreements with the ditch company. The Peterson Ditch is an earthen channel structure that passes just to the north ofthe proposed reservoir site. A preliminary survey investigation indicated that there is a sufficient change in elevation between the ditch and the reservoir to allow for gravity diversions from the Peterson Ditch. Based on a preliminary survey ofthe Peterson Ditch and the reservoir area, gravity diversions from the ditch can be utilized to fill the reservoir to the high water line. This is a better condition than the Sedgwick site that would have required pumping to top off the reservOIr. A conversation with the operator ofthe Peterson Ditch revealed no apparent conflicts and excess capacity available if the ditch was utilized for a winter fill of the reservoir. The only other diversion below the proposed project, that is active during the winter period, is the diversion for the Lower South Platte Recharge project. The Lower South Platte Recharge site is capable of diverting 30-40 cfs (limited by the capacity of the recharge site). The operating capacity of the Peterson Ditch, according to the ditch rider, is approximately 90 cfs. The ditch rider indicated that the limiting factor for ditch capacity is bank erosion in the steeper sections of the ditch near the headgate. The capacity of the ditch increases above the proposed release structure. There are several inflow points upstream that capture stormwater that flows down the ditch. There may be some opportunity to divert these stormwater flows if water quality and administration issues can be adequately addressed. The Peterson Ditch is decreed for 534 cfs under two separate decrees, but the diversion records for the past eight years indicate that 101 cfs was the maximum diversion that has occurred. The second decree, which is junior to the compact, has not been utilized and is on the list for abandonment. The operator of the ditch indicated that there also is a possibility of diverting flows for this project via the Peterson Ditch during the spring runoff. Diversions during the spring runoff period would not be consistent, due to the fact that diversions would be dependent upon the available capacity of the ditch after the ditch shareholder's flow requirements were met. An alternate to allow diversions when shareholders are using the capacity ofthe ditch is to enlarge the capacity of the ditch in the reach from the river to the reservoir to accommodate the junior fill decree of the reservoir. This would insure no injury to present users under the ditch. It is estimated that an enlargement would run between 30 to 50 cfs of capacity. There are many additional issues associated with this concept that need to be addressed. The Julesberg Irrigation District is key in any use of this structure and will need to give approval for any proposed modifications. This alternate will need further study during the preliminary design phase and is not a part of the construction cost estimates. The present configuration ofthe Peterson Ditch diversion structure is capable of diverting all flows from the South Platte River up to ditch capacity. The structure is a wood sheet pile structure with a concrete cap. The structure for the Peterson Ditch is apparently in poor condition and there is a concern that the structure is in need of replacement. The general concern is that the streambed is degrading downstream of the structure, which eventually could cause the structure to fail. It is unknown at this time if any corrective action is slated to repair or replace the diversion structure. 8