EXECUTIVE SUMMARY

Similar to most western watersheds, the Roaring Fork Watershed’s flows have been, and continue to be, altered to meet agricultural, municipal, and industrial demands within and beyond the watershed boundaries. Aspects of the flow regime, including flow magnitude, timing and duration of high and low flows, and rate of change, are related to important biological and geomorphological processes that influence overall stream health. With the recent recognition of the importance of stream health to the economic and environmental sustainability of the watershed, government officials and stakeholders are more willing to identify and pursue flow regimes that meet biological needs while still providing beneficial consumptive uses. This dialog brings forth some important questions such as “how much water is needed, at what times, and for what duration?”.

These questions frame the Roaring Fork Watershed Stream Flow Survey Project (the Project). This report covers the project data collection and analyses preformed to date. Optimum conditions for one species or process may not be optimum for another; therefore, identifying desired flows should not focus on the needs of a single aspect. Stream ecosystems have evolved to adapt to a range of conditions, known as the range of natural variability. The range of natural variability for each flow parameter can be determined using daily mean stream flow data, where a sufficient period of unaltered flow data is available. The Project has involved gathering and synthesizing relevant data and assessing the applicability of appropriate tools to identify broad ecologically sustainable flow thresholds and critical areas to protect or restore. Hydrologic alteration was assessed for the Roaring Fork Watershed using daily mean stream flow gage data from three sources, as well as modeled stream flow data and several analytical methods. The modeled data representing pre-developed and developed monthly flows for the period of record (1908-1996) for 33 locations throughout the watershed provided better temporal and spatial representation of flows than the available gage data. A third assessment was made using real time daily mean stream flow data to determine how often and when Colorado Water Conservation Board instream flows were met.

The results of these analyses are discussed for the nine sub-watersheds in the Roaring Fork Watershed. We found that much of the significant hydrologic alteration is seasonal, contributed by activities such as irrigated agriculture or snowmaking. Although, the alterations can be severe (occur over all months in a season), there is a significant return flow from these activities. Other water uses cause hydrologic alteration throughout the year including trans-mountain diversions, Ruedi Reservoir management, and diversion for domestic water supplies. For example, Nettle Creek, a small tributary of the Crystal River that supplies water to Carbondale, experiences year-round hydrologic alteration. The trans-mountain diversions are one hundred percent consumptive. In the case of the Upper Roaring Fork River Sub-Watershed the effects occur in all seasons and result in unfulfilled CWCB instream flow rights. Although the Boustead Tunnel in the Fryingpan River Sub-Watershed diverts more water than the Twin Lakes Tunnel, severe effects in this sub-watershed are not seen year-round. Overall hydrologic alteration below Ruedi Reservoir is rated as severe. However, unlike many other alterations that result in lower, developed flows are significantly higher than pre-developed flows in all seasons for at least a period of one month.

These results, along with conservation targets identified by The Nature Conservancy’s Conservation Action Planning Process, will be used to prioritize areas for more in-depth hydrologic analyses. Additionally, these results will be instrumental in identifying water quantity issues for the newly initiated watershed planning process. Integration with the design of the watershed plan enhances our ability to reach the overall Project goal, which is to respond to instream flow issues and pursue approaches for achieving sustainable stream flows. Plans to improve flows in two highly altered areas, and an overview of several potential flow protection or restoration options to achieve sustainable stream flows, are presented as they relate to the overall project goal.

We extend our gratitude to all of this study’s financial supporters and partners. This is a unique, exciting, and ambitious effort and we couldn’t have made the progress we have, or be able to continue with the project’s vision, without the support of and belief in its goals and overall significance for maintaining healthy stream systems within the Roaring Fork Watershed. The Roaring Fork Watershed Collaborative Water Group perceived the need for the Stream Flow Survey Project. Two individuals, Randy Russell, Garfield County and Cindy Houben, Pitkin County, were instrumental in getting the project started. Kristine Crandall spearheaded the project’s initial phases, provided background information throughout the project and invaluable comments on a draft report. This project would not have been possible without the initiative and support of the past Roaring Fork Conservancy Executive Director, Jeanne Beaudry, the ongoing support of the current Executive Director, Rick Lofaro and the support of the Board of Directors. The Conservancy’s Education Director Tim O’Keefe continues to incorporate information from the Project into outreach presentations and reviewed this study report. Eliza Hothckiss, Office Manager, provided help and good cheer in abundance. 

Key to the project success was funding provided by: the National Fish and Wildlife Foundation, Colorado Conservation Trust, Colorado Watershed Protection Fund, Garfield County, Eagle County, Pitkin County, ESRI Conservation Program and the Environment Foundation. We gratefully acknowledge the support of project partners and look forward to continuing relationships. Specifically, The Nature Conservancy who participated in project planning, provided technical guidance, reviewed grants and report drafts, and helped with education/outreach. Their Conservation Action Planning Process in the Roaring Fork Watershed is closely linked to the Stream Flow Survey Project. Specific thanks to Tom Iseman, Terri Schulz, Albert Slap, Robert Wigington, Chris Pague, and Mike Tetrault. Don Meyer, Dave Kanzer, Jim Pearce, and Dave Merritt from The Colorado River Water Conservation District were extremely helpful in overall project planning as well as providing technical GIS assistance and help in understanding CDSS StateMod data and other technical water issues. John Carney and Peter Nichols with the Colorado Water Trust support the goal of the project and are working with us to pursue options for achieving sustainable flows. 

Several people that provided ideas, technical assistance and data were important to the study. Sheree Lynne, a graduate student from University of Colorado-Colorado Springs, provided invaluable ideas for data analyses and helped with data analyses. Colorado Water Conservation Board’s Michelle Garrison promptly and graciously answered numerous questions regarding CDSS StateMod data. Two past Conservancy employees helped with the project. Jacob Bornstein provided statistical guidance and Chrissy Sloan, a legal fellow, provided policy guidance. Mark Lacy and Andrea Holland Sears, U.S. Forest Service, provided ideas and insight into this study. George Wear from the Colorado Division of Water Resources and Mark Henneberg from the Bureau of Reclamation provided help accessing stream gage data and background information about stream gage operations. Dean Wieser, Snowmass Water and Sanitation District provided stream gage data for Snowmass Creek.