Presented at the Washington-British Columbia Chapter’s 2015 Annual Meeting for the American Fisheries Society and the 26th Northeast Pacific Pink and Chum Salmon Workshop, “A Comparison of Desktop Hydrologic Methods for Determining Environmental Flows” was recently published in the Canadian Water Resources Journal. Researched and written by Ecofish Senior Environmental Scientist Todd Hatfield in collaboration with Alberta Dept. of Environmental and Sustainable Resource Development’s Andrew Paul, this paper reviews different desktop methods and their performance on a range of streams in British Columbia; moreover, it highlights the need for clearly defined objectives when utilizing these methods for any water allocation decision. This paper can be accessed online at: http://www.tandfonline.com/doi/full/10.1080/07011784.2015.1050459.
Determining environmental flows can be a daunting task because fluvial systems are physically and biologically complex, and there can be difficult trade-offs between instream and out-of-stream water uses. Desktop methods are office-based exercises that use readily available hydrologic information to assess a proposed diversion of stream flows. This paper reviews six well- known desktop hydrologic methods. Seventeen performance measures (PMs), for ecosystem health (hydrology, habitat, geomorphology, connectivity, and water quality) and out-of- stream water use, are used to compare and contrast the predicted outcome of the desktop methods to three mid-size rivers with different hydrologic regimes. Results of the PM calculations demonstrate that absolute and relative performance of the six desktop methods is not consistent across the three streams. As a group, the desktop methods clearly underscored the trade-off between water use and ecosystem health; however, the methods had widely divergent performance for water use PMs and variable performance on the different ecosystem health PMs. All desktop methods performed well on the fish habitat PMs, but performance on the other ecosystem health PMs was variable and not consistent among methods. The results emphasize the need for clearly articulated objectives as an integral component of any desktop method and the benefit of transparent trade-off considerations during any water allocation decision.