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Pagosa Springs San Juan/Delores River Div 7 Response Letter
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Pagosa Springs San Juan/Delores River Div 7 Response Letter
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Last modified
11/6/2014 12:00:03 PM
Creation date
10/27/2014 11:54:50 AM
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Water Supply Protection
Description
Dave Rosgen respone letter on the San Juan River in Pagosa Springs, CO
State
CO
Basin
San Juan/Dolores
Water Division
7
Date
1/1/2007
Author
Dave Rosgen
Title
Pagosa Springs WWP, San Juan/Delores Division 7 Dave Rosgen's response letter
Water Supply Pro - Doc Type
Correspondence
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• <br /> concrete is not necessary for stability, I think its use is inappropriate based on the <br /> objectives stated for this work. In the Engineering Department at Colorado State <br /> Univerisity, Dr.Brian Bledsoe has monitored the structures on the Little Snake <br /> River system for five years. These structures have proven to be very stable. <br /> Hundreds of structures were installed (W-weirs, cross-vanes,J-hooks, etc) <br /> without any concrete, and many of these structures were installed on bedrock <br /> similar to the previous projects on the San Juan River. Thinking that one must use <br /> concrete to have a stable in-stream structure would be a dangerous precedent to <br /> set! <br /> 3. A proposed new river structure is planned immediately above the Hot Springs <br /> Blvd bridge. The current structure is due to be replaced by a U drop structure. <br /> The existing structure has been in place for 10 years, has withstood higher floods <br /> than in 2005, provides fish habitat and bridge protection due to near-bank stress <br /> reduction, and has not had any stability or safety issues. Since this structure has <br /> met its design objectives and performed well over 10 years,why replace it? If the <br /> objectives of the new work are similar to the previous objectives, why disturb the <br /> habitat and reconstruct a concreted check dam to replace it? Since public funds <br /> were used to build this structure using"Fishing for Fun" grant monies, the <br /> structures are to be maintained for at least 20 years as part of the agreement with <br /> the State—the proposal violates previous agreements. Why tear out a structure <br /> and disturb the site and the fishery habitat created when it is a functional <br /> structure? I suggest seeking opinions from the user groups, especially the <br /> kayakers and the Colorado Division of Wildlife,before"replacing"this structure. <br /> I have numerous photographs and video of kayakers "surfing"the waves in this <br /> favorite location. Why aren't public monies spent on creating boating and habitat <br /> where it does not exist? The reaches of the San Juan River below the foot bridge <br /> are definitely in need of enhancement as they are not at their potential. <br /> 4. The W-weir above the foot bridge in Town is proposed to be replaced with a U <br /> drop, concreted structure. What is the documented-evidence that the existing <br /> structure needs to be replaced? The U drop structure created obvious bank <br /> erosion across from the Chamber of Commerce building following snowmelt <br /> runoff. This bank erosion did not occur in the past in the presence of the W-weir <br /> at flows higher than experienced in the snowmelt runoff spring of 2005. <br /> Apparently, the use of boulder rip-rap is proposed to reduce anticipated bank <br /> erosion from this structure. The improved aesthetics objective is not met by the <br /> use of boulder rip-rap instead of riparian vegetation, which is necessary for long- <br /> term stability and enhanced fishery(shading, detritus, and terrestrial insect <br /> availability for food). Hard control of this nature is not new,but is it consistent <br /> with the objectives of the planned work?...I don't think so! An alternative to hard <br /> control is strongly recommended. The U drop structure will also direct velocity <br /> vectors straight into the location where the foot bridge foundation sets on easily <br /> eroded travertine material. There is also a hot water pipeline above this site that <br /> also would be at risk. If this structure is constructed as designed, an additional <br /> structure(such as a J-Hook or Cross-Vane structure) would redirect the velocity <br /> core away from the bank/bridge location. The plan does not show any proposed <br />
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