C150372 Approval Letter - Laserfiche WebLink

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Oligarchy Irrigation Company October 18, 2013 (Updated October 21, 2013) Page 3 of 5 Water Rights The water rights impacted by this project include TABLE 1: IMPACTED DIRECT FLOW WATER RIGHTS Agenda Item 8d Name Amount (CFS A ro riation Date Ad. udication Date Oligarchy Ditch 43.95 6/1/1866 6/2/1882 Oligarchy Ditch 98.65 12/1/1870 6/2/1882 Oligarchy Ditch 36.84 3/1/1872 6/2/1882 Oligarchy Ditch 58.07 1 4/1/1874 1 6/2/1882 TABLE 2: IMPACTED STORAGE WATER RIGHTS Name Amount AF A ro riation Date Adjudication Date Union Reservoir 13,219 10/6/1902 3/13/1907 Union Reservoir 5,879 5/1/1973 3/11/1977 McIntosh Reservoir 2,460 10/8/1902 3/13/1907 McIntosh Reservoir 2,460 1 12/31/1929 7/23/1951 Average annual diversions through the diversion structure are 7,966 AF Project Description The Project goal is to reconstruct the Company's St. Vrain Creek diversion structure, which was destroyed by the September 12 -16, 2013 flood, including the diversion dam, sand gate, Rubicon flumegate, headgates, and bypass gate. The Company has retained Deere and Ault Consultants, Inc. to provide design and construction review services. Alternative 1 — Do Nothing: This alternative is considered unacceptable. Failure to replace the diversion structure would prevent the diversion of the Company's water rights and the inability to uphold the Company's responsibility to deliver Union Reservoir and McIntosh Reservoir water rights. Selected Alternative 2 — Rebuilding Collaboratively with Improvements: The Oligarchy Ditch already serves multiple users and interest including its shareholders, and the owners of Union and McIntosh Reservoirs. The Rubicon flumegate serves the interests of the St. Vrain Creek Corridor Committee for preserving streamflow past the structure. Because of the relatively isolated location of the Oligarchy Diversion (nearest headgates are nearly one mile upstream and one mile downstream), no practical means of serving additional multiple interests were identified. The Project will reconstruct the damaged facilities in the same location, size and for the same function as the pre -flood structure, with improvements to provide a long lasting installation. The rebuilt structure will provide a better hydraulic cutoff and energy dissipation which should provide additional protection of the structure under future flood flow conditions. The original structure had one sand gate into which the Rubicon flumegate was installed. For better operation and river administration, the rebuilt diversion will separate the sand gate and the flumegate into their own passages through the diversion dam.