Stream-restoration projects are usually designed to improve habitat quality for fishes. These projects manipulate flow patterns, substrate distribution, and amount and placement of large woody debris. Consequently, they also affect the size and composition of the aquatic macroinvertebrate community. This research evaluates two types of fish habitat restoration: off-channel structures (alcoves) and in-channel structures (log weirs). I compared macroinvertebrate habitats and communities in natural and artificial alcoves in Upper and South Fork Lobster Creeks, Lane Co., and examined the effects of log weirs on in-channel habitat diversity, community composition, drift patterns, and fish consumption of macroinvertebrates. Macroinvertebrate samples were collected from artificial and natural alcoves using hand pumps and D-nets. Within the channel, macroinvertebrates were collected from restored and unrestored reaches with a Hess sampler and using a stratified random sampling scheme. Forty-eight hour invertebrate drift samples were obtained at outlets of log-weir pools. Stomach contents were obtained from coho salmon (Oncorhynchus kisutch) and cutthroat trout (O. clarki) in restored reaches. Although natural alcoves differed from artificial in location within the floodplain, morphology, permanence, and degree of interaction with the stream channel, both alcovetypes provided similar habitats and contained similar macroinvertebrate communities. Average densities and diversity within the alcoves depended on habitat and time of year. Average densities were higher in artificial than in natural. Alcoves contained 29% of species richness within Upper Lobster Creek. Within the stream channel, the diversity of macroinvertebrate habitat was lower in restored than in unrestored sections. Log weirs were associated with reduced taxonomic and functional feeding-group diversity. Composition of drift was not significantly different in restored and unrestored areas; however, drift densities were significantly lower in restored reaches. Diets of fishes in restored areas were composed primarily of organisms produced from outside restored areas. Although in-channel structures may enhance physical habitat for fishes, they may alter or reduce the availability of food for fishes feeding on drifting invertebrates. Recommendations are given for improving the design of stream restoration projects with respect to macroinvertebrates; however stream restoration should focus on restoring whole-system integrity and function, instead of targeting just one or two types of organisms. / Graduation date: 1996

Seven streams, one of them permanent, were studied in western Oregon, USA. The research was designed to assess the value of summer-dry headwaters for conservation oriented landscape management. Streams were categorized primarily according to exposure (forest versus meadow sites) and secondarily according to flow duration (ephemeral = short-flow versus temporary = long-flow sites). Ephemeral streams have discontinuous flow and last less than three months annually. Temporary streams have continuous flow for more than five months each season. Ephemeral forest streams were highly efficient at filtering road-generated sediment. Uptake lengths for suspended sediment were short (36 m-105 m) at moderately elevated input concentrations. As a result of the filtration mechanism, filtration efficiency is expected to increase as annual flow duration decreases. Injection experiments yielded nitrate uptake rates of almost 1% per m of temporary stream channel. Exchange with subsurface flow was the most important route for nitrate removal from the water column. Biological uptake was insignificant in a light-limited forest stream, whereas a considerable amount of nitrate was retained by the biota a nutrient-limited meadow channel. At least 207 insect species were collected from the summer-dry streams. Species richness recorded from temporary forest streams exceeded that in an adjacent permanent headwater and there was high overlap between the fauna of the permanent and the temporary streams. Species richness in ephemeral channels was only 1/4 to 1/3 of that in long-flow forest streams. Multivariate analysis of community structure revealed flow duration and microhabitat pattern (riffle-pool) as the most important environmental factors determining faunal composition in temporary forest streams. Summer drought conditions at the sample sites also were important. By providing habitat and contributing to water quality in permanent downstream reaches, summer-dry streams have the potential to serve multiple purposes in conservation management. Their value from a conservation perspective is unexpectedly high. Landscape management therefore should be directed toward the preservation and protection of ephemeral and temporary streams. / Graduation date: 1993

Responses of juvenile steelhead trout to changes in stream habitat resulting from an instream habitat rehabilitation project in Meadow Creek, Oregon were measured from 1991 through 1992 and compared to pre-treatment data from 1987 through 1990. Sixty nine pool-forming, and 59 channel-stabilizing log structures were constructed by the U.S. Forest Service in a 3.7 km reach in 1990. A 20-year flood caused extensive modifications to the instream structures in May 1991. Pool habitat and large wood volume increased in the treatment and the two reference reaches but pool development was greater in the treatment reach compared to the two reference reaches. Summer rearing densities of juvenile steelhead were similar for the treatment and the two reference reaches at the reach scale. Summer rearing densities were lower in the post-treatment period compared to the pre-treatment period for the treatment and two reference reaches. Mean density of juvenile steelhead was higher in complex pools compared to non-complex pools throughout the study area. Mean density of juvenile steelhead was higher in pools associated with large wood from washed-out structures compared to pools associated with intact structures in the treatment reach. Changes in smolt production from the treatment reach following the rehabilitation project could not be determined due to trapping difficulties. Only three percent of the smolts emigrating from the basin overwintered in the treatment reach in 1992. Four life history patterns of juvenile steelhead were identified. Only one of the four life history patterns rears in the Meadow Creek basin until smolting. From these findings I conclude that the instream habitat rehabilitation project did not increase the abundance of juvenile steelhead or smolt production during the first two years after treatment. An extended drought and a 20-year flood may have been the dominant factors controlling abundance of juvenile steelhead over the study period. The Meadow Creek rehabilitation project may have limited success at increasing smolt production because it influences only one of four life history patterns of juvenile steelhead during the entire freshwater rearing phase. / Graduation date: 1997

The restoration of rivers and streams should be based on a strong conceptual framework. Streams are developing systems. As such, streams exhibit temporal behaviors that change with changing stream environments. Underlying the dynamic development of streams is potential capacity. Streams express this capacity as an array of habitats over time and across the landscape. Human land uses in the western United States have rapidly altered aquatic habitats as well as the processes that shape habitat. As a result, the diversity of native fishes and their habitats has been suppressed. Restoration is fundamentally about allowing stream systems to re-express their capacities. Four steps are provided to guide stream restoration activities. Key tasks include: identification of the historic patterns of habitat development; protection of the developmental diversity that remains; local application of specific knowledge about suppressive factors; classification of sensitive, critical or refugium habitats; release of anthropogenic suppression; and monitoring of biotic response to habitat change. Applying these concepts, I describe potential habitat refugia for aquatic organisms in the Joseph Creek basin in the Blue Mountains of northeast Oregon. Five valley segment classes, differing in valley corridor landforms, are described. Of these, low-gradient wide alluvial valleys have been most altered by human land use. Riparian vegetation has been extensively removed or altered in alluvial valleys. Currently, stream habitats are structurally depauperate, and warm to temperatures well above thermal tolerances of native salmonids. Potential refugia for native coldwater fishes in these valleys include patches of complex habitat within stream reaches. Reaches fenced to exclude domestic livestock exhibit narrower channels, more pools, and higher frequencies of stable vegetated banks than nearby unfenced reaches. During summer low flow periods, cold groundwater seeping into and accumulating in stream channels forms "cold pools". Cold pools provide potential seasonal refuge for coldwater fish at microhabitat scales. Cold pools are associated with channel complexity, and are more frequent in reaches with vigorous riparian vegetation. Seven classes of cold pools are described. Cold pool classes differ in minimum temperature, maximum depth and volume. Distributions of cold pool classes between valley segment classes suggest that valley geomorphology in addition to local channel form may influence development of certain cold pool types. Although refugia at the microhabitat to reach scales are important, the context within which remnant or refugium habitats and associated relict populations are maintained may ultimately determine the persistence of those species and habitats. In managed landscapes, protection and restoration of habitats at many scales may be necessary if we are to best insure the persistence of native species. / Graduation date: 1995

Forested lands of western Oregon provide aquatic habitat for many fish and riparian dependent species, including a wide variety of salmon species. Current policies set riparian protections using fixed buffers on streams for federal and private lands based on stream type or size. These buffers can create a series of disjointed riparian protections, as federal lands require buffers that are much larger than private lands. In addition, the fixed buffer approach is neither flexible nor tailored to aquatic ecosystem values. This thesis presents a framework for comprehensively assessing stream networks using site specific watershed features and then suggests riparian conservation strategies that key stream and riparian protection to aquatic ecosystem values. Seven study watersheds were used in this analysis, totaling over 2.5 million acres of forested lands in western Oregon. Employing a set of geospatial tools, called NetMap, streams in each watershed were classified into higher and lower priorities using criteria of intrinsic potential, erosion/debris flow susceptibility, and thermal loading potential. Results demonstrated the inherent variability within and among watersheds based on the geomorphic and ecological processes determined important for selected salmon species. Within each watershed, both federal and non-federal lands had many miles of higher priority fish-bearing and non-fish bearing streams, suggesting the need for comprehensive, holistic watershed conservation strategies. Based on the partitioning of streams into higher and lower priorities, an alternative riparian conservation strategy was then modeled for federal lands that allocate protection on the basis of the ecological context of a stream segment’s potential and particular location while still meeting federal aquatic conservation goals and objectives. Possible increases to the land base for long-term timber production were then identified if this strategy were applied to federal Matrix lands. Results demonstrated that 8-30 percent of the current riparian buffers could be reallocated to the land base for long-term timber production. An additional 26-45 percent of current buffers could be managed simultaneously for both timber production and aquatic ecosystem goals. Results also provided a framework for targeting of conservation and restoration efforts towards higher priority streams within each watershed. As many of the most ecologically important streams were located on non-federal lands, riparian conservation policies focused on streams classified as higher priority on those lands may be needed to protect aquatic species and their environments. / Graduation date: 2013