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5 | Page CWCB Feasibility Study – County Road 52 Improvements & Grading Representatives of these entities met over a period of two years to consider ways to mitigate flood hazards within the area that is tributary to Boxelder Creek from County Road 70 north of Wellington south to where Boxelder Creek floodwaters join the Cache La Poudre River. It was determined that the best approach to basin wide flood hazard mitigation would be to prepare a common plan for flood mitigation improvements within the Basin. Members of the Alliance pooled funding to prepare a storm water Master Plan for the Boxelder Basin. The resulting Boxelder Creek Regional Stormwater Master Plan (Master Plan) was completed in October 2006. This Master Plan formed the basis for the formation of the Boxelder Basin Regional Stormwater Authority (Authority). The Authority was formed by an Intergovernmental Agreement in August of 2008 by its Member Entities; the City of Fort Collins, Larimer County and The Town of Wellington. The central purpose of the Authority was to develop and construct three regional drainage improvement projects which are shown on Exhibit B. These projects were preliminarily identified in the 2006 Master Plan as: 1. The Coal Creek Flood Mitigation Project 2. Edson Reservoir 3. The Middle Boxelder Improvements The first of these improvement projects, the Coal Creek Flood Mitigation Project, has recently been completed by the Authority in cooperation with Larimer County. The purpose of the project was to protect close to 200 homes, dozens of businesses, and two schools that were within the Coal Creek floodplain in the Town of Wellington. This $5.1M project diverts stormwater flows from Coal Creek (which is tributary to Boxelder Creek) into the Clark Reservoir Inlet Canal and ultimately into Clark Reservoir. North Poudre Irrigation Company (NPIC) owns these facilities, which are north of the Town of Wellington. The Inlet Canal was enlarged to accommodate the 1,700 cfs from Coal Creek, Clark Reservoir was dredged and the emergency spillway was raised to accommodate the decreed storage of NPIC along with the diverted Coal Creek flows. During construction, 186,000 cubic yards of sediment was removed from Clark Reservoir. The dredging combined with raising the emergency spillway provides the 540 acre-feet of flood storage along with the 871 acre-feet of decreed storage for NPIC. Funding for this project came from a FEMA Pre -Disaster Mitigation Grant (PDM), matching funds and Authority Service Fees. The second improvement project identified in the Master Plan was originally called Edson Reservoir. This dry stormwater detention reservoir was only preliminarily sized (660 to 990 ac -ft.) and sited (see Exhibit B) in the Master Plan. A detailed Siting Study was completed by Ayres Associates (May 2010) to determine the most advantageous location for Edson taking into account flood reduction, cost and constructability issues. This Study is summarized in the previous Feasibility Study for what is now referred to as the East Side Detention Facility (ESDF) and explains the ultimate siting of ESDF. The third of the projects, the Middle Basin Improvements, went through a metamorphosis as well. Originally identified in the Master Plan as principally two storm drainage channels and a siphon structure at the crossing of Boxelder Creek and the Larimer and Weld Canal, the improvements were reduced in scope and refined in design. Most of this change in the scope of the improvements had to do with the eventual size and location of the ESDF, which will greatly reduce the Boxelder 100 -year flows where they cross the Larimer and Weld Canal. As a result, these improvements have now been reduced to a single side-flow spillway structure known as the Larimer and Weld Canal Crossing Structure (LWCCS) at the crossing of Boxelder Creek and the Larimer and Weld Canal.