Poudre River Flow Recommendation

Recommended Flow Regime
for the Cache la Poudre River
Through Fort Collins, Colorado


by John Bartholow [johnb @ FossilCreekSoft .com]


It is generally agreed that river rehabilitation most often relies on restoring a more natural flow regime, but credibly defining the desired regime can be problematic. I combined four distinct methods to develop and refine month-by-month and event-based flow recommendations to protect and partially restore the ecological integrity of the Cache la Poudre River through Fort Collins, Colorado. A statistical hydrologic approach was used to summarize the river's natural flow regime and set provisional monthly flow targets at levels that were historically exceeded 75 percent of the time. These preliminary monthly targets were honed using results from three Poudre-specific disciplinary studies. A substrate maintenance flow model was used to better define the high flows needed to flush accumulated sediment from the river's channel and help sustain the riparian zone in this snowmelt-dominated river. A hydraulic/habitat model and a water temperature model were both used to better define the minimum flows necessary to maintain a thriving cool water fishery. The result is a range of recommended monthly flows and daily flow guidance illustrating the advantage of combining a wide range of available disciplinary information, supplemented by judgment, in a highly altered, working river.


Download most recent version of the flow recommendation: MainstemPoudreFlowRec5.pdf


What Others Have Said Regarding this Proposal

1.  "Thanks for doing this, well done.  ... I am very grateful for your efforts.  Overall, I think the report provides a sorely needed foundation for adaptive management of the river ecosystem through Fort Collins. ... The numbers you propose can serve as reasonable preliminary estimates until the relationships, especially for channel and riparian corridor maintenance, can be better quantified with existing models."


Brian P. Bledsoe
Department of Civil and Environmental Engineering
Engineering Research Center
Colorado State University
Fort Collins, CO

2.  "Thanks for taking the initiative to craft a flow regime recommendation that is flexible, yet provides the range of variability needed to help sustain the linked aquatic-riparian ecosystem of the Poudre in Fort Collins.  I hope that your working model will foster discussion to improve current and future water management proposals for the basin."

Kurt Fausch
Department of Fish, Wildlife, and Conservation Biology
Colorado State University
Fort Collins, CO

3.   "I have read your well prepared Recommend Flow Regime for the Poudre River proposal and I commend you for your effort. Thank you.
The proposal puts forth a convincing argument for a flow designed to restore and maintain the environmental integrity of the Poudre.
Yes, I am very willing to give my support to this proposal."
Jim Henriksen
Environmental Flow Specialists, Inc.
Fort Collins, CO

Author of Henriksen, J.A, J. Heasley, J.G. Kennen, and S. Nieswand. 2006. Users' manual for the Hydroecological Integrity Assessment Process software (including the New Jersey Assessment Tools). Open-File Report 2006-1093. Fort Collins, CO: U.S. Geological Survey, Fort Collins Science Center. 71 p.

4.  "I believe you have put together an important synthesis of data relevant to the sustaining the integrity of the Poudre River.  ... Presenting a novel (but science-based) view for management of the river allows your proposal to stand on its own as a competing vision for the river.  

I hope your efforts are rewarded with some serious consideration."

Barry R. Noon, PhD
Department of Fish, Wildlife, and Conservation Biology
Colorado State University
Fort Collins, CO

5.  "I endorse the recommended flow regime for the Cache la Poudre River through Fort Collins, Colorado proposed by John Bartholow.  The recommended flow regime is a responsible recommendation of a flow regime that would protect the ecological integrity of the Cache la Poudre River."

Robert T Milhous
USGS Hydrologist (ret.)
Fort Collins, CO

6.  "This document articulates how the present geomorphic and ecological functioning of the Poudre River is maintained by a naturally variable flow regime. The flow recommendation for the Poudre is based on an impressive synthesis of a broad literature on contemporary river science.  Importantly, the document provides a valuable starting point for an informed, and much needed, societal discussion of how to manage the river in an ecologically sustainable fashion.  The vision presented here merits serious consideration."

N. LeRoy Poff
Department of Biology
Colorado State University
Fort Collins, CO

7.  "I can endorse the concept. ... We operate on the theory that something less than the ‘full’ natural regime is necessary, and that one can identify flows that maintain the ecology—at least at some acceptable level—while providing water for human uses.  That’s what you have implicitly done here."

John Sanderson
The Nature Conservancy
Fort Collins, CO

8.  "As Trout Unlimited’s Aquatic Specialist, I endorse your approach of synthesizing data from four different methodologies into a flow regime recommendation for the Poudre River that considers natural hydrologic variability, channel maintenance flows, fish habitat requirements, and water temperature issues.  Your paper highlights the thought processes that are required to develop stream flow recommendations that include the critical elements of a flow regime - magnitude, timing, frequency duration and rate of change."
Greg Espegren
Trout Unlimited
Boulder, CO

Additional endorsement statements pending

All comments, or endorsements, welcome