Flows and Recretion: A guide to studies for river professionals

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Study complexity. This increases with the number of flows, length of the reach, number of participants, and types of craft or opportunities under consideration. Controlled flow studies work best when they are focused on discrete flow ranges where more precision is needed, and where boating is expected to be possible and safe. Rugged terrain associated with challenging rivers may increase the logistical challenges and safety /liability risks, which may affect panel and analysis considerations. Safety priorities may also preclude examination of flows near the high or low ends of acceptable ranges, or increase costs if additional emergency equipment or expertise is needed. Cautions & limitations Controlled flow studies are most useful where river segments are short, flows can be definitively controlled, river access is easy, and users are readily available (Shelby et al. 1998). These characteristics are commonly found on bypass reaches at hydropower projects. Applying this method to longer reaches without flow control is more problematic. Controlled flow studies for boating focus on immediate effects on hydraulics, but they may not document longer -term indirect effects that may be important for boating or other recreation. These studies also may not address a diversity of flows through a season unless there are resources to examine many flows. They are better suited as a tool to identify specific flows that may be released as an augmentation for one or two opportunities. California's Pit 5 Bypass Reach during a controlled study (1,260 cfs shown here). The study examined six /lows from 250 to 1,840 cfs. Optimal ranges started about 1,200 cfs for kayaks and 1,500 cfs for rafts. Flows and Recreation: 27 A Guide for River Professionals