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I I I I I I I I I I I I I I I I I I I rapidly, most likely due to freeze-thaw effects. The concrete is somewhat porous in nature due to the large size of aggregate used, and no air entraining was utilized in past times to increase its resistance to freeze-thaw. Portions of the structure have cracked and fallen off, and the downstream concrete apron is broken into pieces in some areas. The upstream approach slab is highly eroded and has broken off in some areas. The defect that may cause the greatest concern is the poor joint contact between the piers and the base slab. The piers support the gates and stop logs and take the full force of the hydrostatic head. Shear at the joint is in excess of 25,000 pounds per pier which would be insignificant if the joints were sound. Due to the poor condition of the diversion structure, the potential for failure during a flood is real. The structure's operational platform (walkway) is low enough that trash accumulation often occurs during a flood which creates a dam across the structure. The gates cannot be raised above high water which would allow floating debris to pass. This could increase the pressure on the structure by as much as 50 percent and decrease the overall stability, similarly, by as much as 50 percent. A failure of the structure would impede the Owner from diverting into the canal creating the potential for a loss of at least 21,000 acre-feet of water per year. This could produce enormous losses to the agricultural water users in the New Cache La Poudre system if the structure could not be utilized to divert water during the irrigation season. Some temporary structure could be placed in the river but could not be accomplished until after the flood had passed. Any temporary solution would be expensive and would take from weeks to months to construct. 3. Svstem ODeration The water right is administered by the Water Commissioner for the Cache La Poudre River system. Based upon discussions with the Commissioner and with The New Cache La Poudre Manager, the water supply at the diversion has been administered on a main channel control structure. That is, the Commissioner only requires that flows below the structure be sufficient to provide for senior right. The senior rights downstream are two decrees to the B. H. Eaton for 51.5 cfs and to the Whitney Ditch for 29.1 cfs. The river section downstream of the diversion has been rated to determine the flow at different gauge heights. However, the date of the rating and the accuracy are in question. The allocation of water in the Poudre River system is based on filling senior direct diversion rights in order of priority or order of rank within the system. This system of f11ling the water right with the highest priority first is essentially followed. However, in wet years, reservoirs in the system are often filled out of order. PAGE 2 - CbapterV