City Of Greeley
 

Cache La Poudre River General Investigation Study


Inquires may be directed to Dave.wells@greeleygov.com

Study Location, Purposes, and Costs

The US Army Corps of Engineers and the City of Greeley are conducting a Feasibility Study of the Cache La Poudre River in and near Greeley. The study area is the lower 17 miles of the river, from its confluence with the South Platte River upstream. The primary purposes of the study are to identify cost-justified  projects that will reduce flood damages and/or improve wildlife habitat.  This study will cost approximately $2,610,000, with most  of the costs split 50/50 between the City of Greeley and the Corps of Engineers. The City has received $300,000 in grants from the Colorado Water Conservation Board to help with the City's share.

Status Summary

The US Army Corps of Engineers is in the final months of the study. The Corps evaluated several levee alignments for the high damage reach through Greeley, to determine levee benefit to cost ratios. Unfortunately, no levee alignment has been found with average annual benefits exceeding average annual costs, i.e., a benefit/cost ratio over 1.0, which is the Corps benchmark for being feasible and supportable. Focus has turned to "nonstructural" alternatives, such as elevation residences above flood elevation or building a flood-proof barrier around non-residential properties. Separately, work is nearly complete on environmental restoration plans at numerous locations along the Cache la Poudre River. A draft Feasibility report will be available for public review period in spring of 2014. The study will be completed in the summer of 2014.

Background

A Reconnaissance level study was completed in 2004, which found that a Feasibility study was merited. Work on the Feasibility study began in February, 2006 and will be complete in 2014. The Feasibility study included an initial investigation of potential flood damage reduction along the urbanized reach of the Cache la Poudre in Greeley. This investigation completed in May 2008, indicated there was a likelihood that a levee project could be feasible; that is, it could have a benefit to cost ratio greater than 1.0.
The Corps also generated reports that identified potential ecosystem restoration opportunities along the Cache la Poudre River. The initial reports, completed by Corps contractor Otter Tail Environmental Inc. summarized existing environmental conditions of the study area and the restoration opportunities.
A public meeting was held December 4th, 2008. Numerous comments and questions were received from interested property owners as well as various local government agencies. The Corp's Omaha District presented information in English and Spanish, and conducted an audience question, answer, and discussion period followed by small group and one-on-one interaction with attendees. A draft Feasibility report was reviewed by the Corps Northwestern Division and Corp Headquarters, and then was released in June 2010. Subsequently, levee cost estimates rose until, in summer 2013, analysis showed that levees no longer appeared economically feasible. Flat terrain meant a costly floodwall was needed at each end of a levee to tie it off. Also, substantial requirements for levee projects to be FEMA certified meant significant cost. These requirements call for a large system of runoff storage basins and pumping systems, to handle 100-year rainfall flooding within the levee-protected area, simultaneous with 100-year river flooding. Because structural levee alternatives do appear infeasible, Corps efforts with Greeley support have focused on nonstructural alternatives. Potential "nonstructural" alternatives include elevating a residence at its existing location, dry flood proofing commercial and public buildings, and wet flood proofing some buildings. Not all buildings within a flood prone area would receive large enough damages in floods to justify the cost of implementing these measures. Of those that did, the property owners would decide whether to participate in a nonstructural measure. The Corps' Omaha District continues to evaluate these potential measures and to explore the Federal and other policies that would apply to them.
Also since 2010, multiple potential ecosystem restoration measures at 9 locations have been evaluated. The costs and benefits of a variety of plans have been compared to each other. A Federally preferred National Ecosystem Restoration Plan has been tentatively been identified, and Greeley is considering its own preferred plan. The Corps and Greeley are also considering the potential for minimally disruptive recreation features to be included with ecosystem restoration areas.  

Meeting Summaries

  • March 19, 2010 Feasibility Scoping Meeting
  • Cache la Poudre at Greeley Draft Feasibility Report ATR
  • June 30, 2009 Executive Committee Meeting
  • May 6, 2008 Advisory Committee Meeting
  • December 5, 2008 Resource Agency Meeting
  • December 4, 2008 Public Scoping Meeting/Workshop
  • September 8, 2006 General Meeting
  • September 7, 2006, Gravel Pit break out meeting
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