Stream restoration was implemented on the Upper Arkansas River near Leadville, Colorado, to improve brown trout (Salmo trutta) populations. Metals pollution and channel disturbance associated with historic mining, land use, and water development degraded aquatic and riparian habitat. Changes in instream habitat quality following restoration were investigated with a before-after-control-impact study design. Baseline, asbuilt, and effectiveness surveys were conducted in 2013, 2014, and 2016, respectively. Two-dimensional hydrodynamic modelling with River2D was used to estimate weighted usable area (WUA) for adult, juvenile, fry, and spawning brown trout across a range of flows. WUA was calculated from habitat suitability curves for velocity, depth, and channel substrate. Foraging positions (FP) and habitat heterogeneity were also evaluated as indices of habitat quality. All results were analysed with analysis of variance. At impact sites, WUA increased by 12.2% from 2013 to 2014 but decreased by 10.2% from 2014 to 2016, whereas FP increased by 24.8% from 2013 to 2014 but decreased by 26.1% from 2014 to 2016. Spawning habitat increased 53.3% from 2014 to 2016 at impact sites. The 15.4% increase in depth variability from 2013 to 2016 indicates that habitat heterogeneity was enhanced at impact sites. No changes in WUA, FP, or habitat heterogeneity were observed at control sites. Although changes in WUA and FP suggest that initial habitat improvements were not sustained, increased spawning habitat and depth heterogeneity suggest otherwise. Our results highlight the value of monitoring strategies that utilize multiple lines of evidence to evaluate restoration effectiveness, inform adaptive management, and improve restoration practices.

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The use of mobile radio frequency identification (RFID) systems to detect PIT tags has increased in support of research on fish movement, population dynamics, and habitat use. We describe the development and application of a mobile RFID system that incorporates GPS to detect PIT‐tagged fish and evaluate habitat utilization in streams. The study was conducted in two distinct phases. First, development and testing of the RFID–GPS system were conducted using georeferenced, PIT‐tagged rocks to evaluate detection probability and GPS accuracy. Second, the system was field deployed to estimate the abundance of PIT‐tagged fish and evaluate habitat utilization. Detection probability was negatively influenced by stream width, distance from the stream center, and water depth, whereas detection probability increased with the number of passes. The GPS error between detected and surveyed positions averaged 4.5 m, with greater error observed in longitude than in latitude. Because of high capture and recapture probabilities, abundance estimation of PIT‐tagged fish was not only possible but also relatively precise. All detections during field deployment were assigned habitat types using the “intersect,” “closest,” and “buffer” methods in ArcGIS. Analysis of habitat utilization was limited to two bedform classes, riffles and pools, because the average area of runs and glides was smaller than the average GPS error. More Brown Trout Salmo trutta were detected in pools (76–80%) than in riffles, and all Rainbow Trout Oncorhynchus mykiss and cutbow trout (Cutthroat Trout O. clarkii × Rainbow Trout) were detected in pools. The detection field covered more cross‐sectional area in pools than in riffles, which could have influenced the analysis of habitat utilization. The influence of GPS error on habitat evaluations will depend on stream size, as erroneous habitat associations should diminish as stream size increases. The flexibility of the RFID–GPS system makes it useful for a variety of studies related to habitat utilization, fish migration, and population trends. Received March 31, 2017; accepted August 19, 2017 Published online October 20, 2017

Whitewater parks (WWPs) are increasingly popular recreational amenities, but the effects of WWPs on fish habitat and passage are poorly understood. This study investigated the use of a two‐dimensional (2‐D) model as compared with a three‐dimensional (3‐D) hydrodynamic model (flow‐3D®) for assessing effects of WWPs on fish habitat. The primary aims of this study were to (1) examine the utility of 3‐D modelling versus 2‐D modelling in a hydraulically complex WWP and (2) compare modelled habitat quality for resident fishes with actual fish abundance and biomass generated from field sampling surveys. Two reaches of a wadeable river in Colorado were modelled: a natural reach and a reach containing a WWP. A 2‐D habitat suitability analysis for juvenile and adult brown trout, juvenile and adult rainbow trout, longnose dace and longnose sucker predicted the same or higher habitat quality in the WWPs than the natural pools for all four species and for all modelled flow rates; however, results from fish sampling found significantly higher fish biomass for all four species in natural pools compared with WWP pools. All hydraulic metrics (depth, depth‐averaged velocity, turbulent kinetic energy, 2‐D and 3‐D vorticity) had higher magnitudes in WWP pools than in natural pools. In the WWP pools, 3‐D model results described the spatial distribution of flow characteristics or the magnitude of variables better than 2‐D results. This supports the use of 3‐D modelling for complex flows found in WWPs, but improved understanding of linkages between fish habitat quality and 3‐D hydraulic descriptors is needed. Copyright © 2015 John Wiley & Sons, Ltd.

Stream habitat fragmentation caused by manmade structures is ubiquitous in Colorado, creating a need for passage solutions that accommodate multiple fish species. This study tested the effectiveness of a rock-ramp fishway to pass nine fish species with a range of swimming abilities. Target species for fishway design included Brassy Minnow Hybognathus hankinsoni (weakest swimming), Longnose Dace Rhinichthys cataractae, Longnose Sucker Catostomus catostomus, and Brown Trout Salmo trutta (strongest swimming). Testing included a 46-hour enclosure study and three-month extended study, during which fish passage was evaluated using PIT tags. All species exhibited successful passage through the fishway during the enclosure study, but movement