Project

Asotin Creek Intensively Monitored Watershed Experiment

Goal: To determine the effectiveness of a common stream restoration method (addition of large woody debris) to increase the geomorphic and habitat diversity of sections of Asotin Creek and to monitor the response of juvenile steelhead to the restoration. Specifically changes in abundance, growth, movement, and production of juvenile steelhead in treatment and control sections will be compared both pre and post restoration for a period of at least 10-15 years.

Methods: Mark-Recapture, Lidar Bathymetry, Lidar Remote Sensing, net rate of energy intake, columbia habitat monitoring protocol

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Stephen N. Bennett
added a research item
The Asotin Creek Intensively Monitored Watershed Project was established in 2008 as a large-scale, long-term experiment to test the effectiveness of stream restoration at improving freshwater habitat conditions and increasing production and productivity of a wild summer run steelhead population. Asotin Creek is recovering from past disturbances such as riparian clearing, channel straightening, removal of large woody debris, and excessive sediment from upland farming practices. However, the majority of channels are still single thread, have low large woody debris frequency, limited floodplain connection, and consist of mostly planar geomorphic features (e.g., runs, rapids). To increase geomorphic diversity, we developed and implemented a low-tech process-based restoration method we call High-density Large Woody Debris (HDLWD) using post-assisted log structures (PALS) to create hand-built debris jams. The project area includes three tributaries to Asotin Creek and in each tributary we established three 4 km long monitoring sections, two control and one treatment section in each tributary (total study area 36 km). We have monitored juvenile steelhead since 2008 using passive integrated transponder (PIT) tags and mark-recapture methods to estimate abundance, growth, emigration, survival, production, and productivity in treatment and control sections – pre and post-restoration. Washington Department of Fish and Wildlife also provide monitoring of juvenile emigration and adult escapement near the mouth of Asotin Creek. We installed over 650 PALS in 14 km of treatment area from 2012-2016 using a staircase experimental design. To date the restoration has been effective at increasing instream complexity of steelhead habitat by forcing greater hydraulic diversity, which has led to greater pool and bar frequency and area, developing more off-channel habitat, and promoted tree recruitment. However, there has been limited floodplain connection. As a result, juvenile abundance has increased in treatment areas with minimal changes in growth or survival which suggests either egg-fry or fry-juvenile survival may have increased due to restoration. Preliminary results also suggest biomass and production of juvenile steelhead has increased in treatment sections. The increases in fish abundance and production so far are modest (15-40% increases) but we hypothesize that the greatest population increases will be realized when the restoration promotes “greater floodplain reconnection” and the project is poised to demonstrate this in the coming years. The results from this IMW will have broad applications to wadeable streams across western North America that make up the majority of stream miles in a watershed and will help to promote cost-effective and science-based approaches to stream restoration and recovery of ESA listed salmon and steelhead.
Stephen N. Bennett
added 2 research items
Before-after-control-impact (BACI) experimental designs are commonly used in large-scale environmental experiments but these designs can be confounded by location and time interactions. Staircase designs, where replicate treatments are staggered temporally, have been suggested as an alternative to BACI designs. We performed a simulation study based on data from an ongoing watershed-scale restoration experiment within three streams to test the effectiveness of adding large wood to increase habitat complexity and abundance and productivity of juvenile steelhead (Oncorhynchus mykiss). We compared the power of two asymmetric BACI (aBACI) designs to two staircase designs for detecting changes in the density of steelhead (fish/m2). A staircase design where treatments were temporally staggered in one treatment section in each stream had the highest power and best precision, especially when the innate spatial and temporal variances of steelhead density were large. A traditional BACI performed the worst, and a variation on another BACI and staircase design had intermediate performance. Multi-stream staircase designs are also more logistically and economically feasible and can maximize learning by replicating experiments across different stream types.
Stephen N. Bennett
added a research item
Background The Asotin Creek Intensively Monitored Watershed (IMW) was implemented in 2008. The focal species are natural reproducing summer steelhead. Based on previous habitat assessments and preliminary IMW monitoring it was decided that riparian function and instream habitat complexity were impaired. The restoration proposed was fencing, native plant revegetation, and weed control to enhance riparian function in the long-term, and the addition of large woody debris (LWD) in the short-term to increase habitat diversity and promote a more dynamic channel (e.g., increase sediment sorting, pool frequency, and floodplain connection). We implemented the IMW using a staircase experimental design where restoration actions were implemented in different years starting in 2012 and ending in 2016 in three different streams. Each stream is divided into three 4 km long sections and one or more sections has been restored in each stream with the remaining sections acting as controls. We have built 654 large woody debris structures at an average density of 4.7 structures per 100 m in the treatment sections (~39% of the study area has been restored and 61% remains as controls). We have continued to add LWD to treatment sections as needed based on annual habitat survey results in order to keep the density of wood high in treatment sections compared to control areas (annual maintenance). We are using extensive habitat sampling and fish PIT tagging and resighting to estimate habitat changes and changes juvenile steelhead abundance, growth, survival, movement, production, and productivity in each experimental section. There are five passive transponder tag (PIT) interrogation sites within Asotin Creek that are used to monitor adult and juvenile PIT tag steelhead movement in Asotin Creek watershed – three of these sites (ACM, ACB, AFC) were upgraded with new equipment in 2018. Analyses Approaches We continue to develop and refine tools/models to help us analyze our data. We completed and present summary results on the following analyses: • Geomorphic unit delineation tool (GUT) to quantify geomorphic units (e.g., pools, bars, planar features) from topographic data collected from Columbia Habitat Monitoring (CHaMP) data we collect at 18 sites (105 visits). • Barker model for calculating true survival, site fidelity, and probability of captures. We have now completed and run all fish capture and resighting data for each season and year from 2008-2016 • Bayesian based model for aging all of our fish using a subsample of known ages and acquired from scale samples and fish lengths. We use the age model to estimate the age of tagged fish that were not aged with scales so that we can determine the brood year of migrants and calculate migrants per female as well as assess treatment responses by age class. All tagged juvenile steelhead have been aged to 2017. • Net rate of energy intake model (NREI) has been run for all CHaMP site visits from 2011-2017 to estimate the fish capacity changes by year. • Staircase statistical models to analyze juvenile steelhead abundance 2008-2017 (previously presented) • Migrant production of treatment and control sites pre and post restoration have been estimated from 2008-2017 by estimating the number of migrants (smolts) by age class and then back-calculating the brood year they came from using PIT tag detections at the interrogation sites at the mouths of each IMW study stream. Trends Habitat • We continue to see habitat responses that are in line with many of original hypotheses of treatment areas becoming more complex after restoration, but the changes are inconsistent. • The frequency of wood in the treatments is staying high relative to the control sections. • The frequency of pools and bars has increased in some treatment areas compared to control areas. • Geomorphic unit analyses are not as clean as we would have hoped and provides mixed results on habitat change. Fish • We have observed positive trends in fish abundance and are beginning to see difference in the fish response by stream. Like the habitat changes, the fish response in the North Fork appears to be greater than the other two streams despite being treated last (i.e., we are observing a Year 3 response in North Fork, Year 4 in Charley, and Year 5 in South Fork). • We observed a positive increase in survival (especially fall) in treatment sections compared control sections • Migrant production is highest in North Fork, but Charley and South Fork migrants/female is consistently higher. • Very preliminary analysis suggests that there may be a positive trend in the productivity of treatment sections compared to control sections General • It appears that responses, both habitat fish, are positive but relatively small and inconsistent. One explanation for this is the stream types themselves. They are confined streams with limited floodplain habitat. The North Fork appears to be responding to most to restoration and this may be because it has higher stream flow and more floodplain – so restoration can make relatively more habitat (and habitat change) than in Charley and South Fork. We are considering what options we have (including more restoration) based on our analysis to date. • We have implemented a robust design, completed a large restoration treatment, maintained a high quality data stream for both habitat and fish for 11 years, developed a series of geomorphically and empirically based set of tools to summarize raw data, and developed a staircase statistical model to analyze these data and separate multiple sources of variance from the true treatment response. • We are now in the phase of the project where we need to complete enough years of post-treatment monitoring to complete the migrants/female table, develop models that can explain what factors are driving the responses we see (i.e., causal mechanisms), and assessing if the responses are consistent, persistent, and how they vary between stream types.
Stephen N. Bennett
added a research item
Before-after-control-impact (BACI) experimental designs are commonly used in large-scale experiments to test for environmental impacts. However, high natural variability of environmental conditions and populations, and low replication in both treatment and control areas in time and space hampers detection of responses. We compare the power of two asymmetric BACI (aBACI) designs to two staircase designs for detecting changes in juvenile steelhead (Oncorhynchus mykiss) abundance associated with a watershed-scale stream restoration experiment. We performed a simulation study to estimate the effect of a 25% increase in steelhead abundance using spatial and temporal estimates of variance from an ongoing study, and determined the power of each design. Experimental designs were then applied to three streams and each stream was composed of three 4 km long sections. We compared the power of a single treatment section in one stream (BACI-1), three simultaneous treatments of all sections in one stream (BACI-3), three sequential treatments in one stream (STAIRCASE-1), and three sequential treatments in one section in each stream (STAIRCASE-3). All designs had > 94% power to detect a 25% increase in abundance assuming average variance. Under worst-case variance (i.e., upper 95% confidence limits of historical variance estimates), the STAIRCASE-3 design outperformed the BACI-1, BACI-3, and STAIRCASE-1 designs (i.e., 77%, 41%, 8%, and 33% power respectively). All the designs estimated the effect of the simulated 25% abundance increase, but the length of the confidence interval was much shorter for the STAIRCASE-3 design compared to the other designs, which had confidence intervals 58-596% longer. The STAIRCASE-3 design continued to have high power (88%) to detect a 10% change in abundance, but the power of the other designs was much lower (range 34-56%). Our study demonstrates that staircase designs can have significant advantages over BACI designs and therefore should be more widely used for testing environmental impacts.
Stephen N. Bennett
added 2 research items
The effectiveness of past anadromous stream habitat restoration actions has been hard to determine because few restoration projects were implemented in an experimental fashion, or were not large enough to produce a detectable effect size. Recently, a series of Intensively Monitored Watersheds (IMWs) have been established with the explicit intent to determine the population response of anadromous salmonids to watershed scale restoration actions. Paramount to the successful development and implementation of an IMW is a robust and logistically feasible experimental design. Optimal experimental designs seek to account for the significant sources of variability while achieving large enough effect size. Because replication at a watershed scale is often not logistically feasible, before-after-control-impact (BACI) designs are often used to test the effect of restoration treatments. However, implementation of a large treatment within a single year can also be logistically infeasible, and the analysis results of a BACI design can be ambiguous due to failure to account for the random effects of year-treatment interactions. An alternative to BACI designs is a staircase design whereby treatment applications are staggered over time. We use historic steelhead monitoring data (redd counts and juvenile abundance estimates) and data from an ongoing IMW in the Asotin Creek in southeast Washington to assess the power of different experimental designs to detect treatment responses. The Asotin IMW monitors summer steelhead populations and stream habitat in three tributaries in Asotin Creek. Each tributary has three 4 km long sections that are subsampled with 500 m reaches. A series of simulations were used to compare the power of the staircase design to a BACI design, and variations of a simple staircase design. The simulation results demonstrate that the power of different experimental designs is strongly influenced by sources of variance within sections of streams, between sections within the same stream, and between streams. All designs we tested were able to detect a 25% change in juvenile steelhead abundance when low-to-moderate variances were assumed. However, an alternative staircase design that treats one section of each tributary in a staggered fashion had greater power (60-70%) to detect a 25% change than all the other designs (25-30% power) when variability was high. We show how these simulations can inform the selection of appropriate experimental designs to detect population level responses to restoration actions.
Environmental stressors associated with human land and water-use activities have degraded many riparian ecosystems across the western United States. These stressors include (i) the widespread expansion of invasive plant species that displace native vegetation and exacerbate streamflow and sediment regime alteration; (ii) agricultural and urban development in valley bottoms that decouple streams and rivers from their floodplains and reduce instream wood recruitment and retention; and (iii) flow modification that reduces water quantity and quality, degrading aquatic habitats. Here we apply a novel drainage network model to assess the impacts of multiple stressors on reach-scale riparian condition across two large U.S. regions. In this application, we performed a riparian condition assessment evaluating three dominant stressors: (1) riparian vegetation departure from historical condition; (2) land-use intensity within valley bottoms; and (3) floodplain fragmentation caused by infrastructure within valley bottoms, combining these stressors in a fuzzy inference system. We used freely available, geospatial data to estimate reach-scale (500 m) riparian condition for 52,800 km of perennial streams and rivers, 25,600 km in Utah, and 27,200 km in 12 watersheds of the interior Columbia River Basin (CRB). Model outputs showed that riparian condition has been at least moderately impaired across ≈70% of the streams and rivers in Utah and ≈49% in the CRB. We found 84% agreement (Cohen’s ĸ = 0.79) between modeled reaches and field plots, indicating that modeled riparian condition reasonably approximates on-the-ground conditions. Our approach to assessing riparian condition can be used to prioritize watershed-scale floodplain conservation and restoration by providing network-scale data on the extent and severity of riparian degradation. The approach that we applied here is flexible and can be expanded to run with additional riparian stressor data and/or finer resolution input data.
Stephen N. Bennett
added 2 research items
AbstractWe conducted simulations to compare the precision and bias of survival estimates from Cormack?Jolly?Seber (CJS) and Barker models to known parameter values based on empirical data for steelhead/resident Rainbow Trout Oncorhynchus mykiss from the John Day River, Oregon. We simulated seasonal differences in recapture and survival rates, and we varied the number of fish tagged, recapture and resight rates, sample site size, and fish movement (migratory or resident). Survival estimates from the Barker model had higher precision and lower or equal bias in comparison with estimates from the CJS model under almost all simulation scenarios. The precision of Barker survival estimates increased the most as the number of tagged fish increased from 50 to 200 (CV = 0.4?0.09). The Barker model's superior performance was dependent on the availability of resight data; such data are becoming more readily available, especially in places where large numbers of individuals are PIT-tagged and where an interrogation infrastructure exists (e.g., Columbia River basin). Tagging of 75?100 fish/site during high-capture periods (e.g., summer and fall) and focusing on the resighting of fish with fixed or mobile interrogators during low-capture periods (i.e., winter and spring) may be the most cost-effective strategy for improving estimates of juvenile steelhead survival.Received April 18, 2014; accepted August 26, 2014
Substantial research effort has been devoted to understanding stream-dwelling salmonids’ use of summer rearing and growth habitat, with a subset of studies focusing on foraging position selection and the energetic trade-offs of differential habitat use. To date, however, cost–benefit analyses for most foraging model studies have focused on small sampling areas such as individual habitat units. To address this knowledge gap, we applied a mechanistic foraging model to 22 stream reaches (100–400 m) from two watersheds within the Columbia River Basin. We found a strong, positive correlation (R2 = 0.61, p < 0.001) between predicted carrying capacities and observed fish densities. Predicted proportion of suitable habitat was weakly correlated with observed fish density (R2 = 0.18, p = 0.051), but the mean net rate of energy intake prediction in sampling reaches was not a significant predictor of observed fish biomass. Our results suggest spatial configuration of habitat, in addition to quantity and quality, is an important determinant of habitat use. Further, carrying capacity predicted by the model shows promise as a habitat metric. We also evaluated the feasibility of applying this data-intensive modeling approach in a large-scale monitoring program to examine habitat quality and quantity. Though the approach can be computationally expensive, we feel the model’s ability to integrate physical habitat metrics (e.g., depth, velocity) with important biological considerations like food availability and temperature is a benefit that far outweighs associated costs. We feel this modeling approach has great potential as a tool to help understand habitat use in drift-feeding fishes. © 2016, National Research Council of Canada. All rights reserved.
Stephen N. Bennett
added 2 research items
Despite substantial effort and resources being invested in habitat rehabilitation for stream fishes, mechanistic approaches to designing and evaluating how habitat actions influence the fish populations they are intended to benefit remain rare. We used a Net Rate of Energy Intake (NREI) model to examine expected and observed changes in energetic habitat quality and capacity from woody debris additions in a 40-m-long study reach being treated as part of a restoration experiment in Asotin Creek, WA. We simulated depths, velocities, and NREI values for pre-treatment, expected, and post-treatment habitat conditions, and we compared pre-treatment vs. expected and pre-treatment vs. post-treatment simulation results. The pre-treatment vs. expected topography simulations suggested treatment would increase energetically favorable area, mean NREI, and capacity in the study reach. Pre-treatment vs. post-treatment comparisons yielded similar predictions, though to smaller magnitudes, likely due to the short time span and single high flow event between pre- and post-treatment data collection. We feel the NREI modelling approach is an important tool for improving the efficacy of habitat rehabilitation actions for stream fishes.
Closed population models are commonly used to estimate stream salmonid abundances using mark–recapture information collected during electrofishing surveys. To meet the model assumption of geographic closure, block nets are often used to prevent emigration and immigration of fish during the survey. Increased sampling and tagging efforts in an open site may be an appealing trade off given the time it takes to properly deploy block nets, but it also increases an abundance estimate’s vulnerability to bias. We assess the extent of geographic closure violation from emigration in open sites between mark and recapture passes utilizing passive integrated transponder antennas as virtual block nets. This allowed us to quantify emigration rates of juvenile steelhead (Oncorhynchus mykiss) from 60 fish surveys across multiple seasons and watersheds. Our goals were to determine how season and site length influence emigration, examine how the life history of an anadromous salmonid may induce bias on mark–recapture abundance estimates, and to provide recommendations on minimizing the bias associated with violating the geographic closure assumption. Average emigration rate was low across all surveys and watersheds (5.1%), with higher emigration rates correlating with larger fish, shorter site length, and the season in which the site was sampled. We conclude that the bias associated with violating the geographic closure assumption in an open site can be minimized by avoiding times of migration, and sampling sites up to 650 m long depending on fish density and capture efficiency. Our findings provide useful information for planning mark–recapture studies that have multiple sampling objectives. Received 27 Jul 2016 accepted 24 May 2017 revised 19 May 2017
Reid Camp
added 2 research items
Winter is commonly seen as a bottleneck for salmonid survival due to unbalanced energetics in cold temperatures, physical disturbance from ice formation or movement, a lack of preferred habitat, or any combination of multiple stressors. Salmonids can avoid some of these stressors by concealing themselves in interstitial spaces in the substrate. Quality of winter concealment habitat is a function of substrate size, water velocity, embeddedness, and temperature. We monitored steelhead (Oncorhynchus mykiss) winter concealment behavior using passive integrated transponders and mobile antennas. We identified and rated benthic environment characteristics at the sub-meter scale to define quality winter concealment habitat. Winter concealment is an important life history strategy for juvenile steelhead to maintain their growth rates and survival through harsh winters. Restoration projects that alter the substrate need to be aware of the importance of winter concealment habitat in regions where winter concealment behavior is likely to occur.
Poor data management, lost data sheets, and data entry errors plague project managers after every field season. Using mobile technology, we can alleviate many of the data issues that arise when data is handed from field crews to supervisors. Mobile devices are getting cheaper and application development software is becoming more accessible for all users; however, private consultation for custom mobile databases is still expensive. We are using FileMaker software to create database forms that can be deployed on any apple (iOS) device such as iPads and iPhones. FileMaker is a relational database software that allows users with little programming experience to create data forms. The ease of use, low cost, and availability of rugged cases make iOS devices ideal for data entry in remote conditions. FileMaker allows users to enter data offline, then sync to a central database after returning to cellular or Wi-Fi service. Using these mobile database forms forces crews to enter data in a precise structure and prevents data entry errors. We will present the benefits and limitations of using FileMaker for database solutions. We will also demonstrate the applications we have been developing and deploying in the field across Utah, Oregon, and Washington.
Reid Camp
added 3 research items
Fieldwork is a major component of nearly every geoscience discipline. Over the past 3 decades, scientists have amassed an array of specialized instrumentation and equipment to help them measure and monitor a staggering assortment of geophysical phenomena.
In response to human impacts, river restoration and rehabilitation actions have become a priority in the United States. In the Pacific Northwest, most restoration actions are focused on repairing degraded freshwater habitat to increase or improve Pacific salmonid production. However, traditional river restoration actions remained largely unchanged for over 100 years despite a lack of definitive evidence that the actions were effective. More recently, there has been a surge in process-based restoration actions, which aim to reestablish the physical and biological processes that maintain fluvial and floodplain environments by targeting the root causes of degradation in a watershed. Cheap and cheerful restoration projects focus on restoration actions that are low impact and cost effective, can be implemented over large scales, and target degraded processes. However, because cheap and cheerful restoration is a relatively new method, the success of these types of projects has not been assessed. To address this issue, I studied the short-term physical effectiveness of a type of cheap and cheerful restoration that uses high density large woody debris (HDLWD) to restore instream habitat complexity in two wadeable tributaries to Asotin Creek in southeast Washington State. My specific research objectives included (1) assessing hydraulic and geomorphic responses in the stream channel imposed by restoration structures, (2) quantifying the changes to geomorphic channel unit assemblages post restoration, (3) quantifying changes in sediment storage post restoration, and (4) developing a geomorphic condition assessment of Asotin Creek using the River Styles Framework. Additionally, I developed a mobile database application (app) to facilitate data collection using a novel rapid restoration effectiveness assessment survey. Through analysis and a thorough review of the land use history in Asotin Creek, I determined that much of the watershed is in poor geomorphic condition based on the River Styles Framework for river classification. Many stream reaches have been degraded from their historic condition and often lack habitat complexity associated with suitable rearing habitat for juvenile salmonids. My results indicate that the structures are impose several immediate hydraulic responses following installation. These hydraulic responses increase hydraulic roughness, which results in predictable geomorphic responses following high flow events. Following restoration, the number and area of pools and bars significantly increased within treatment sites, while the number and area of planar units decreased. Likewise, it appears that the addition of the structures has led to a 25% increase in depositional volume at treatment sites compared to control sites. Results from the rapid assessment approach supported the more vetted approaches used to assess the efficacy of the treatment. However, the viability of the app and rapid protocol indicate that inter-observer variability may be high, and estimates of geomorphic unit area are not entirely consistent with the vetted approaches. Analysis of the rapid assessment approach revealed pertinent improvements to the app and rapid protocol that will be made in the future.
Stephen N. Bennett
added 4 research items
This report summarizes the first four years of pre-restoration IMW monitoring and infrastructure development. Restoration began in the summer of 2012 and be implemented in a hierarchical-staircase design (see below) in three tributaries to Asotin Creek over three consecutive years. Monitoring of the restoration effectiveness will continue until 2018.
EXECUTIVE SUMMARY Asotin Creek in southeast Washington was chosen as a site to develop an Intensively Monitored Watershed Project (IMW). The purpose of the IMW program is to implement stream restoration actions in an experimental framework to determine the effectiveness of restoration at increasing salmon and steelhead production and to identify casual mechanisms of the fish response to help guide restoration actions in other watersheds. Asotin Creek is designated a wild steelhead refuge and steelhead are the focus of the IMW. • The Asotin Creek IMW has a hierarchical-staircase experimental design which includes the lower 12 km of three tributaries: Charley Creek, North Fork Asotin Creek, and South Fork Asotin Creek (hereafter the study creeks). Each study creek is divided in three 4 km long sections and one section of each creek will be treated (i.e., restoration applied) with the remaining sections acting as controls. Treatments will be staggered over three years with one section treated each year starting in 2012. A total of 12 km will be treated. • The study creeks consist primarily of highly homogenized and degraded habitats, which are thought to be limiting steelhead production. One of the primary limiting factors in these study creeks is a lack of pool habitat and cover for fish, particularly a relatively low abundance, density and mean size of large woody debris (LWD) compared to reference conditions and assumed historic recruitment levels. Therefore, LWD restoration treatments have been proposed for the Asotin IMW. • The addition of LWD to streams to improve habitat complexity and quality is not a new restoration strategy. However, we argue that most projects place undue focus on the size and stability of LWD with frequent attempts to anchor LWD in place. From a stream or watershed perspective, we think that the low density of LWD is a much bigger problem than the size, and streams with healthy rates of LWD recruitment see much more dynamic behavior in their LWD (i.e., it moves regularly). We seek to produce a population-level response in steelhead in the Asotin Creek Watershed by treating over 12 km of stream in three study creeks with 500 – 600 LWD structures. We expect this to fundamentally alter the complexity of habitat at three sections within the project area inducing an increase in steelhead production at the stream scale. • To achieve the desired LWD densities with traditional treatment methods would be extremely expensive, highly disruptive to the existing riparian vegetation, and logistically infeasible to implement over the broad range of steelhead habitat in the Columbia Basin. We instead propose to test the effectiveness of a simple, unobtrusive, method of installing Dynamic Woody Structures (DWS), which are constructed of wood posts, driven into the streambed, and augmented with LWD cut to lengths that can be moved by hand. • Dynamic Woody Structures are installed with a hand-carried, hydraulic post-pounder by a crew of 2-4 people. Typical installation time is on the order of 1-2 hours per structure and material costs are < $100. Thus, if the treatment method proves effective, this is potentially an easy and cost-effective method to transfer to other streams. • Dynamic Woody Structures, like naturally occurring LWD jams, are designed to produce an immediate hydraulic response by constricting the flow width. Like natural LWD accumulations, this alteration of the flow field creates more hydraulic heterogeneity, providing shear zones for energy conservation for fish next to swift areas with high rates of invertebrate drift. Moreover, the convergent flow produced by the constriction is likely to scour and/or maintain pools at high flows, and divergent flow downstream of the DWS where the stream width expands, may promote active bars that provide good spawning habitat. • The fate of an individual structure is not as critical as the overall density of structures. A high density of DWS will increase the large-scale roughness of the stream section creating much more variability in flow width and opportunities to build, alter, and maintain complex assemblages of active bar and pool habitat. Ultimately, we hope to use the DWS to initiate a more regular exchange of materials (sediment, water, LWD, etc.) with the adjacent riparian area. • We have articulated these predicted responses into a series of explicit design hypotheses, which are guiding our monitoring efforts. The monitoring is part of an adaptive management plan and is nested within the hierarchal-staircase experimental design. A targeted blend of detailed, habitat monitoring and fish sampling nested within treatment and control sections is combined with coarser-grained rapid assessment inventories and remote sensing at the stream and watershed scale. This approach ensures that we can reliably detect and infer mechanisms of geomorphic changes and fish response at local scales, but we can then reasonably expand these understandings to the stream and population scales. • The staggered implementation of the restoration (i.e., staircase design) provides explicit opportunities within the adaptive management plan to refine and adapt implementation and monitoring specifics as may be necessary. • Preliminary results from the performance of 15 trial structures installed in the summer of 2011 suggest that the structures are able to withstand higher than average spring floods (the peak March 2012 discharge was the largest in 12 years at the confluence of North Fork and South Fork) and produced many of the intended hydraulic and geomorphic responses.
Stephen N. Bennett
added 2 research items
Across the Pacific Northwest, at least 17 intensively monitored watershed projects have been implemented to test the effectiveness of a broad range of stream restoration actions for increasing the freshwater production of salmon and steelhead and to better understand fish–habitat relationships. We assess the scope and status of these projects and report on challenges implementing them. We suggest that all intensively monitored watersheds should contain key elements based on sound experimental design concepts and be implemented within an adaptive management framework to maximize learning. The most significant challenges reported by groups were (1) improving coordination between funders, restoration groups, and researchers so that restoration and monitoring actions occur based on the project design and (2) maintaining consistent funding to conduct annual monitoring and evaluation of data. However, we conclude that despite these challenges, the intensively monitored watershed approach is the most reliable means of assessing the efficacy of watershed-scale restoration.
• Asotin Creek in southeast Washington was chosen as a site to develop an Intensively Monitored Watershed Project (IMW). The goal of the IMW is to implement stream restoration actions in an experimental framework to determine the effectiveness of restoration at increasing salmon and steelhead production and to identify casual mechanisms of the fish response to help guide restoration actions in other watersheds. Asotin Creek is designated a wild steelhead refuge and steelhead are the focus of the IMW. • The Asotin Creek IMW has a hierarchical-staircase experimental design which includes the lower 12 km of three tributaries: Charley Creek, North Fork Asotin Creek, and South Fork Asotin Creek (hereafter the study creeks). Each study creek is divided in three 4 km long sections and one section of each creek has been treated (i.e., restoration applied) with the remaining sections acting as controls. Treatments were staggered over three years with one section treated each year starting in 2012. • The study creeks consist primarily of highly homogenized and degraded habitats, which are thought to be limiting steelhead production. One of the primary limiting factors in these study creeks is riparian function which has led to a lack of pool habitat and cover for fish, and a relatively low abundance, density and mean size of large woody debris (LWD) compared to reference conditions and assumed historic recruitment levels. • The addition of LWD to streams to improve habitat complexity and quality is not a new restoration strategy. However, we argue that most projects place undue focus on the size and stability of LWD with frequent attempts to anchor LWD in place. From a stream or watershed perspective, we think that the low density of LWD is a much bigger problem than the size, and streams with healthy rates of LWD recruitment see much more dynamic behavior in their LWD (i.e., it moves regularly). We seek to produce a population-level response in steelhead in the Asotin Creek Watershed by treating over 12 km of stream in three study creeks with 500 – 600 LWD structures. We expect this to fundamentally alter the complexity of habitat at three sections within the project area inducing an increase in steelhead production at the stream scale. • To achieve the desired LWD densities with traditional treatment methods would be extremely expensive, highly disruptive to the existing riparian vegetation, and logistically infeasible to implement over the broad range of steelhead habitat in the Columbia Basin. We instead propose to test the effectiveness of a installing post-assisted log structures (PALS), which are constructed of wood posts, driven into the streambed, and augmented with LWD cut to lengths that can be moved by hand. • Post-assisted log structures were installed with a hand-carried, hydraulic post-pounder by a crew of 2-4 people. Typical installation time is on the order of 1-2 hours per structure and material costs are < $100. Thus, if the treatment method proves effective, this is potentially cost-effective method to transfer to other streams. • Post-assisted log structures, like naturally occurring LWD jams, are designed to produce an immediate hydraulic response by constricting the flow width. Like natural LWD accumulations, this alteration of the flow field creates more hydraulic heterogeneity, providing shear zones for energy conservation for fish next to swift areas with high rates of invertebrate drift. Moreover, the convergent flow produced by the constriction is likely to scour and/or maintain pools at high flows, and divergent flow downstream of the PALS where the stream width expands, may promote active bars that provide good spawning habitat. • The fate of an individual structure is not as critical as the overall density of structures. A high density of PALS will increase the large-scale roughness of the stream section creating much more variability in flow width and opportunities to build, alter, and maintain complex assemblages of active bar and pool habitat. Ultimately, we hope to use the PALS to initiate a more regular exchange of materials (sediment, water, LWD, etc.) with the adjacent riparian area. • We have articulated these predicted responses into a series of explicit design hypotheses, which are guiding our monitoring efforts. The monitoring is part of an adaptive management plan and is nested within the hierarchal-staircase experimental design. A targeted blend of detailed, habitat monitoring and fish sampling nested within treatment and control sections is combined with coarser-grained rapid assessment inventories and remote sensing at the stream and watershed scale. This approach ensures that we can reliably detect and infer mechanisms of geomorphic changes and fish response at local scales, but we can then reasonably expand these understandings to the stream and population scales. • The staggered implementation of the restoration (i.e., staircase design) provides explicit opportunities within the adaptive management plan to refine and adapt implementation and monitoring specifics as may be necessary. • Preliminary results from the performance of over 400 structures installed in the summer of 2011-2013 suggest that the structures are able to withstand higher than average spring floods (the peak March 2012 discharge was the largest in 12 years at the confluence of North Fork and South Fork) and produce many of the intended hydraulic and geomorphic responses. • We have collected a robust set of pre-treatment fish data including abundance, growth, movement, and survival across multiple spatial and temporal scales and are in the process of collecting post-treatment data to determine how effective the restoration has been at increasing steelhead production. • Preliminary estimates indicate fish abundance has increased in treatment sections compared to control sections suggesting that the habitat changes we have observed are improving habitat for fish. • We are developing methods to use PIT tag arrays to assess movement patterns and productivity at the stream and treatment section scales. We have not calculated measures of productivity yet but this will be the focus of the IMW from 2015-2019. • There also is a robust set of fish data at the watershed scale (WDFW Fish In Fish Out), habitat data at various scales from individual restoration structures and geomorphic units to the watershed scale, as well as watershed wide stream temperature, and discharge data that will all be used to interpret fish responses to restoration and help extrapolate results from Asotin Creek to other similar watersheds.
Stephen N. Bennett
added a project goal
To determine the effectiveness of a common stream restoration method (addition of large woody debris) to increase the geomorphic and habitat diversity of sections of Asotin Creek and to monitor the response of juvenile steelhead to the restoration. Specifically changes in abundance, growth, movement, and production of juvenile steelhead in treatment and control sections will be compared both pre and post restoration for a period of at least 10-15 years.