Stream Habitat Conditions Research Articles

Comparing passive and active macroinvertebrate sampling gear efficacy during biomonitoring in Southern Appalachian mountain streams

AbstractAquatic invertebrates are important components of any aquatic ecosystem and are frequently monitored to determine the ecological integrity of those systems. Various gear types are used to collect aquatic macroinvertebrates in wadeable streams. We analyzed commonly used active and passive gear types, including kick seines, Hess samplers, drift nets, and Hester–Dendy samplers, across a watershed in the Great Smoky Mountains National Park to determine their efficacy under various habitat conditions in wadeable Southern Appalachian mountain streams. Hester–Dendy samplers were significantly different from other gear types for most univariate and multivariate analyses. Kick and Hess samples were most similar in multivariate comparisons of macroinvertebrate assemblages. Drift samples were similar in most univariate analyses but were distinct from other gear types when analyzed with multivariate techniques. Our results indicate that comprehensive assessments of macroinvertebrate assemblages require multiple gear types, various analytical approaches, and consistent taxonomic resolution. The complexity of the fluvial system in question should be thoroughly assessed prior to formulating a macroinvertebrate biomonitoring protocol to better ensure robust and meaningful results.

How does over two decades of active wood reintroduction result in changes to stream channel features and aquatic habitats of a forested river system?

AbstractSince the late 1980s and early 1990s, wood reintroduction has been a commonly assessed stream restoration technique. Many of the efforts have focused on short‐term, localized physical changes and response of salmonids to wood reintroduction. Few have examined how long‐term, spatially extensive increases in wood loadings alter stream channel morphology and the geomorphic processes responsible for these changes. We used before and after photos as well as a wood storage survey with tagged restoration logs in a small, low‐elevation Western Washington watershed to characterize the effects of 23 years of wood additions. In the ~6 km of wood placement we saw an increase in wood loading and channel‐spanning logjams, which contributed to deeper and more frequent pools, a reduction in particle size, increases in sediment storage, reduced stream width, vegetation re‐establishment in the riparian zone, and increased development and maintenance of floodplain channels. The largest geomorphic changes occurred due to restoration wood effectively storing pieces moving downstream. These findings imply that the cumulative habitat restoration actions and associated changes to stream habitat conditions are identifiable through comparison of historical and current photos as well as more quantitative habitat metrics. It also demonstrates that wood placement that simulates the function of large key, stable pieces accelerates habitat recovery within basins subjected to historic logging.

Evaluation of two fish-based indices of biotic integrity for assessing coldwater stream health and habitat condition in Iowa’s driftless area, USA

Evaluation of two fish-based indices of biotic integrity for assessing coldwater stream health and habitat condition in Iowa’s driftless area, USA

Hydromorphological Inventory and Evaluation of the Upland Stream: Case Study of a Small Ungauged Catchment in Western Carpathians, Poland

The hydromorphological conditions of watercourses depend on numerous natural and anthropogenic factors such as buffer zones or human infrastructure near their banks. We hypothesised that, even in a small stream, there can be substantial differences in the hydromorphological forms associated with naturalness and human impact. The paper aims at the field inventory and evaluation of the hydromorphological conditions of a small upland stream in the conditions of contemporary human activity, against the background of meteorological and hydrological conditions. The study concerned a left-bank tributary of the Stradomka River located in the Wiśnicz Foothills (Western Carpathians). The analyses were conducted with the use of the Polish method, the Hydromorphological Index for Rivers (HIR), which conforms to the EU Water Framework Directive (WFD). The hydromorphological condition and quality of habitats were evaluated based on the Hydromorphological Diversity Score (HDS) and Habitat Modification Score (HMS). The study shows that the largest changes in stream hydomorphology and habitat conditions took place in the downstream, urbanised stream catchment area with an intensive development of construction and technical infrastructure. The hydromorphological condition of the examined stream sections was evaluated as good or poor. The best hydromorphological conditions were found in the section located in the semi-natural area, and the worst in the urbanised area. As our research shows, the strong influence of human activity, including weather extremes, and the risks and hydrological hazards of the hydromorphological conditions of the small, ungauged catchment, highlight the necessity to search for other research methods to support the decision-making cycle in the transformation of riverbeds and catchments.

Habitat conditions in streams influence Odonata larval assemblages in the eastern Amazon

The growth of agricultural and mining activities in the Amazon has impacted land-use and caused significant changes in the local environmental conditions of streams. In the face of these changes, our study aimed at assessing how environmental changes affect Odonata larval assemblages in streams in the eastern Amazon. We hypothesized that habitat conditions in streams are strong predictors of Odonata larval assemblages. We sampled 30 headwater streams (1st through 3rd order) in the eastern Amazon. We corroborated our hypothesis that regional- and local-scale environmental changes are important predictors of the Odonata larval assemblage structure. These results indicate that environmental conditions within the stream channel are important to maintain Odonata larval assemblages, as they provide important resources for larval development. For new studies, we recommend the assessment of temporal dynamics to evaluate whether these patterns are stable across time. Finally, evaluating various environmental scales of the original impact is extremely relevant for preventing the deterioration of or recuperating aquatic assemblages in Amazonian streams, considering the ongoing rapid environmental changes and deforestation in the region. Here we demonstrate that in-stream environmental conditions are important to assemblage structure and this must be considered in environmental restoration plans.

Epiphyton in Agricultural Streams: Structural Control and Comparison to Epilithon

Stream biofilms play an important role in the structure, functioning, and integrity of agricultural streams. In many lowland streams, macrophyte vegetation is abundant and functions as an important substrate for biofilm (epiphyton) in addition to the gravel and stone substrate for epilithon on the stream bed. We expect that reach-scale habitat conditions in streams (e.g., nutrient availability, hydraulic conditions) affect the epiphyton and epilithon biomass and composition, and that this effect will be substrate-specific (macrophytes and stones). The objectives of our study were (i) to describe concurrent changes in epiphyton and epilithon biomass and composition over a year in agricultural streams, and (ii) to determine the substrate specific reach-scale habitat drivers for the epiphyton and epilithon structure. We monitored epiphyton and epilithon biofilm biomass and composition at three-week intervals and reach-scale environmental conditions daily during a year for two agricultural steams. The results showed that epiphyton and epilithon communities differed in biomass, having high substrate specific biomass in epilithon compared to epiphyton. Epiphyton was mainly composed of diatom and green algae, while cyanobacteria were more important in epilithon, and the diatom species composition varied between the two biofilm types. Epiphyton structural properties were less influenced by reach-scale hydrology and nutrient availability compared to epilithon. The overall explanatory power of the measured environmental variables was low, probably due to micro-scale habitat effects and interactive processes within stream biofilms. Knowledge of biofilm control in agricultural streams is important in order to improve management strategies, and future studies should improve the understanding of micro-scale habitat conditions, interactive relationships within biofilms and between the biofilm and the substrates.

Response of macroinvertebrates to changes in stream flow and habitat conditions in Dinki watershed, central highlands of Ethiopia

Knowledge on the effects of habitat and flow alterations is basis for sustainable stream habitat conservation. This study explores the effects of hydrological and stream habitat alterations on the macroinvertebrates in Dinki watershed headwater streams, central highlands of Ethiopia. A total of 86 macroinvertebrate and water composite samples were collected over 25 sampling reaches in four-round sampling effort. A multivariate analysis of variance (MANOVA) was computed to assess variations in mean values of the three dependent variables (taxa abundance, richness, and diversity) across the independent variables, study sites (Dens, Gedamoch, Hagere-Selam, and Dinki). The mean differences in macroinvertebrate and environmental variables between sampling sites were computed using a one-way analysis of variance (ANOVA). Likewise, a principal component analysis (PCA) was computed to ordinate sampling sites in relation to macroinvertebrates. Furthermore, the resistance and resilience scores were calculated to quantify the invertebrates’ persistence and rate of recovery to habitat and hydrological alterations. The MANOVA indicated a significant spatial variation in taxa abundance. Both the reduced flow and spates had declined assemblage structures in all sampling sites. The PCA also showed that the stream habitat condition influenced the distribution of macroinvertebrates. In general, macroinvertebrate assemblages in both the pre-and-post disturbance events were higher in the forested Gedamoch sites, indicating the role of stream habitat conservation to buffer hydrological disturbances. As a result, management priorities aiming to protect and restore stream condition is a sound mitigation tool to maintain stream condition and its resilience to ecological disturbances.

Measuring stream habitat conditions: Can remote sensing substitute for field data?

The ongoing encroachment of agricultural activities into natural areas is a growing problem for the ecological condition of streams. Stream ecological condition is best measured using both biotic and abiotic parameters that reflect different channel, riparian zone and catchment aspects. Multiple physical-chemical measures of water quality have long been widely used to represent the environmental conditions of water bodies. More recently, physical habitat structure, catchment land use and land cover have been employed to better understand water body conditions. Both water quality and physical habitat structure metrics are usually measured in the field and often have strong predictive power to analyze biological assemblage conditions. On the other hand, remote sensing of catchment land use and land cover provide relatively low-cost environmental information at large spatial extents, minimizing the need for fieldwork and reducing analytical time. Given these considerations, our aim in the present study was to evaluate the degree to which stream environmental conditions could be measured reliably via remote sensing. In particular, we assessed whether a remote sensing index (Normalized Difference Vegetation Index) and land use can be used as reliable surrogates for site habitat condition, channel dimensions, and water quality. We found that our remote sensing variables were not sufficient for predicting stream water quality or habitat structure. Therefore, we recommend using remote sensing indicators only when it is impossible to measure water quality and habitat structure in the field directly.

Forested Riparian Buffers Change the Taxonomic and Functional Composition of Stream Invertebrate Communities in Agricultural Catchments

Riparian zones form the interface between stream and terrestrial ecosystems and play a key role through their vegetation structure in determining stream biodiversity, ecosystem functioning and regulating human impacts, such as warming, nutrient enrichment and sedimentation. We assessed how differing riparian vegetation types influence the structural and functional composition (based on species traits) of stream invertebrate communities in agricultural catchments. We characterized riparian and stream habitat conditions and sampled stream invertebrate communities in 10 independent site pairs, each comprising one “unbuffered” reach lacking woody riparian vegetation and a second downstream reach with a woody riparian buffer. Forested riparian buffers were associated with greater shading, increased gravel content in stream substrates and faster flow velocities. We detected changes in invertebrate taxonomic composition in response to buffer presence, with an increase in sensitive Ephemeroptera, Plecoptera and Trichoptera (EPT) taxa and increases in key invertebrate species traits, including species with preference for gravel substrates and aerial active dispersal as adults. Riparian vegetation independently explained most variation in taxa composition, whereas riparian and instream habitat together explained most variation in functional composition. Our results highlight how changes in stream invertebrate trait distributions may indirectly reflect differences in riparian habitat, with implications for stream health and cross-ecosystem connectivity.

Riverscape nesting dynamics of Neosho Smallmouth Bass: To cluster or not to cluster?

AbstractAimHierarchical stream habitat conditions influence patterns of fish abundance and population dynamics. The spawning period is important for stream fishes but coincides with unpredictable environmental conditions and stressors. Thus, identifying habitats that confer suitable spawning is crucial to managing vulnerable fish populations, including narrow‐range endemics. Here, we evaluate reach‐ and catchment‐scale habitat features related to Neosho Smallmouth Bass (Micropterus dolomieu velox) nest presence, abundance and aggregations (clusters) and quantify nest microhabitat.LocationOzark Highlands ecoregion, USA.MethodsWe conducted snorkel and habitat surveys from 2016 to 2018 to quantify nest abundance, describe nest cluster characteristics and quantify nest microhabitat. We used field‐collected and geospatial variables and developed generalized mixed models to evaluate the influence of multi‐scale habitat features on nest cluster presence and nest abundance.ResultsNest clusters, scarcely known for other Smallmouth Bass populations, contained 25% of all documented nests. Presence of nests was more likely in warmer stream reaches with wide, shallow channels and more pool habitat. Nest cluster presence was more likely with greater nest densities and earlier in the spawning season. The abundance of Smallmouth Bass nests was related to several reach‐scale habitat conditions, with greater nest counts in warmer reaches and reaches with deeper pool habitat. Regardless of cluster behaviour, nesting Smallmouth Bass used similar microhabitats, including a range of depths (0.26–1.85 m), low velocities (<0.1 m/s) and typically gravel substrates.Main conclusionsOur results indicate plasticity in nesting ecology within Neosho Smallmouth Bass populations and highlight the need to consider multiple aspects of stream habitat when developing conservation and management plans. The importance of reach‐scale habitat features suggests it may be important to limit landscape and channel alterations. Nest clustering behaviour suggests these populations may be vulnerable to human influence during the nesting season, but also provides management opportunities for protection during critical time periods.

How Cattle and Wild Ungulate Use of Riparian Areas Effects Measures of Streambank Disturbance

Improper management of cattle near streams can negatively affect the processes that support stream and riparian ecosystems. To judge the success of riparian management strategies, public land management agencies often evaluate two metrics of livestock disturbance, stubble height and streambank alteration. There are concerns associated with how well these disturbance metrics reflect livestock use and incorporate additional effects due to wild ungulates. We sought to address these questions in 39 riparian areas by using time-lapse cameras to estimate ungulate use and then measuring near stream ungulate disturbance in these same reaches. We found daytime measures of livestock use were related to stubble height and streambank alteration. Explaining the variation in the relationship between stubble height and livestock use was improved by incorporating covariates, whereas covariates did little to improve our understanding of streambank alteration. This suggests greater flexibility in how different stream reaches are managed when stubble height is the guideline. As streambank alteration was explained solely by ungulate use, the simplest way to reduce disturbance was to reduce use. In most stream reaches, the additive presence of wild ungulates was minimal but sufficient to be included in the best models describing the effects of ungulate disturbance. On most days, no cattle were seen in the evaluated riparian reaches. Although large groups of cattle (> 20 individuals) were occasionally observed within riparian areas, they generally occurred in small groups of one to four individuals. Across the riparian reaches we evaluated, cattle presence and density were generally low enough that metrics of livestock disturbance suggested little risk to stream conditions important to aquatic biota. However, there were some riparian areas where cattle stayed too long or occurred in large enough numbers that their use along the streambanks could negatively affect stream habitat conditions.

Agricultural water use accounting provides path for surface water use solutions

Agricultural water demands can conflict with habitat needs in many North Coast watersheds. Understanding different water use patterns can help reduce conflict over limited supplies. We measured on-farm crop water use and conducted grower interviews to estimate the agricultural water demand in the upper Russian River and Navarro River watersheds. Annual agricultural water demand was less than 11% in the Russian River, and 2% in Navarro River, of the total annual discharge in each watershed. However, because demands are concentrated in the dry season when instream flows are at a minimum, these relatively small amounts can represent a significant constraint to stream habitat conditions. We have shared our study results in broad basin and community water resource planning efforts, including flow management of the Russian and Navarro rivers and implementation of the Sustainable Groundwater Management Act in the Ukiah Basin. Findings and recommendations from this study have influenced on-the-ground solutions to meet water demand in these watersheds, including construction of off-stream wintertime storage capacity to replace summertime stream diversions, and use of a municipal recycled water conveyance system as a replacement for summer diversions.

Insect-associated bacterial communities in an alpine stream

The roles of macroinvertebrate and microbial communities in stream ecosystems are recognized to be important to energy flow and nutrient cycling. While the linkages of these major groups of aquatic organisms have not been thoroughly investigated, determining how they interact is particularly important for understanding the mechanisms and potential evolutionary relationships that contribute to ecosystem processes, such as organic matter decomposition. We evaluated the microbiomes of several aquatic insect species differing in trophic ecology and belonging to different functional feeding groups at two sites along an Italian Alpine river with different elevation and environmental characteristics, one located above the tree line and the other in a forested environment. We found that the internal microbial communities of the different species significantly varied in taxonomic and functional composition and could be used to classify samples to both species and environment. We demonstrated that functional differences existed between the microbiota of different insect species with variable feeding behaviors, and that species differences were more important, in this context, than environmental or habitat conditions. These results provide new information on how the microbiomes of aquatic insects may potentially be influenced by their hosts and habitat conditions in Alpine streams.

Did changes in western federal land management policies improve salmonid habitat in streams on public lands within the Interior Columbia River Basin?

Historic management actions authorized or allowed by federal land management agencies have had a profound negative effect on salmon, trout, and char populations and their habitats. To rectify past failings, in the 1990s, federal agencies in the Interior Columbia River Basin modified how they conducted land management activities to foster the conservation of aquatic species. The primary policy changes were to provide additional protection and restoration of lands near streams, lakes, and wetlands. What remains uncertain was whether these changes have altered the trajectory of stream habitat conditions. To address this question, we evaluate the status and trends of ten stream habitat attributes; wood frequency, wood volume, residual pool depth, percent pool, pool frequency, pool tail fines (< 6 mm), median particle size, percent undercut banks, bank angle, and streambank stability in managed and reference catchments following changes in management policies. Our review of these data support the hypothesis that changes made in management standards and guidelines in the 1990s are related to improved stream conditions. Determining the precise magnitude of changes in stream conditions that resulted from the modification of land management policies is difficult due to the shifting environmental baseline. By understanding and accounting for how changes in stream conditions reflect improved land management policies and broader environmental trends, federal agencies will be better situated to make project level decisions that benefit aquatic resources.

The first statewide stream macroinvertebrate bioassessment in Washington State with a relative risk and attributable risk analysis for multiple stressors

We report results from the first statewide assessment of biological health in perennial streams in Washington State. Using a probabilistic sampling survey design, we were able to make unbiased estimates of biological condition of macroinvertebrate communities throughout the state based on 346 sites sampled from 2009 to 2012. Results from randomly sampled sites were classified as either good, fair, poor in comparison with 75 regional reference sites that were sampled concurrently. We determined that approximately 34 percent of stream kilometers assessed were in poor biological condition as measured with a multi-metric index, the Benthic Index of Biotic Integrity. Additionally, we evaluated a variety of chemical and physical habitat stressors known to negatively influence macroinvertebrate communities and determined that poor substrate conditions were the most prevalent and important stressors impacting stream macroinvertebrates, with relative bed stability and percent sand/fines being the most prevalent. A relative risk/attributable risk analysis suggests that improving physical habitat conditions in streams, most notably a reduction in percent sand/fines, will have the greatest impact for improving biological condition for macroinvertebrate communities. It is estimated that approximately 60% of stream kilometers now classified as in poor biological condition in Washington could be improved by reducing the amount of percent sand/fines in the substrate. These results are consistent with those obtained from EPA’s national stream surveys and suggest that poor habitat conditions are the most prevalent stressors impacting stream macroinvertebrates in Washington State.

Accuracy and Optimal Altitude for Physical Habitat Assessment (PHA) of Stream Environments Using Unmanned Aerial Vehicles (UAV)

Physical Habitat Assessments (PHA) are useful to characterize and monitor stream and river habitat conditions, but can be costly and time-consuming. Alternative methods for data collection are getting attention, such as Unmanned Aerial Vehicles (UAV). The objective of this work was to evaluate the accuracy of UAV-based remote sensing techniques relative to ground-based PHA measurements, and to determine the influence of flight altitude on those accuracies. A UAV quadcopter equipped with an RGB camera was flown at the altitudes of 30.5 m, 61.0 m, 91.5 m and 122.0 m, and the metrics wetted width (Ww), bankfull width (Wbf) and distance to water (Dw) were compared to field PHA. The UAV-PHA method generated similar values to observed PHA values, but underestimated distance to water, and overestimated wetted width. Bankfull width provided the largest RMSE (25–28%). No systematic error patterns were observed considering the different flight altitudes, and results indicated that all flight altitudes investigated can be reliably used for PHA measurements. However, UAV flight at 61 m provided the most accurate results (CI = 0.05) considering all metrics. All UAV parameters over all altitudes showed significant correlation with observed PHA data, validating the use of UAV-based remote sensing for PHA.

Effect of a baffled chute on stream habitat conditions and biological communities

Despite the occurrence of many low head hydraulic structures in rivers, such as drop hydraulic structures or boulder ramps, there is still a lack of information on how these structures influence stream habitat conditions and biological communities. This lack of knowledge especially applies to baffled chutes, which, to date, have not been the subject of any hydrobiological studies. Our study examined a baffled chute on the Lubenka stream in Poland that was constructed in the early 1970s and rebuilt in 2015 with European Union financial support. We analysed the influence of that particular ramp hydraulic structure on the biological conditions upstream and downstream, looking into the quality and abundance of fish and benthic invertebrates. The Peterka-type baffled chute interfered with the ecosystem of the stream and fundamentally changed the conditions for the organisms in a relatively long section. In the area of the direct impact of the chute, hydraulic parameters changed drastically, which entailed the formation of three new distinct habitats with associated biological communities. The presence of the baffled chute resulted in transformations to the stream's biological communities over relatively long sections. It disrupted the natural balance between deposition and erosion, with the former dominating above the chute and it acted as a barrier to the general movement or migration of aquatic fauna. The Lubenka chute seems to be an example of an ill-considered human intervention that has adversely affected the ecosystem for several decades. Despite this, it was decided to incur large costs for the renovation of the chute rather than opt for its removal or at least to build a fish pass. Given the data presented in this paper, the chute seems to be a clear example of a bad management practice. The application of these solutions (baffled chute) should be limited to artificial wastewater canals. In streambeds, the chute causes drastic and practically irreversible changes.

Influence of Stream Condition on Habitat Diversity and Fish Assemblages in an Impaired Upper Snake River Basin Watershed

AbstractHabitat diversity reflects the range of available habitats used by species with different niche requirements and, therefore, influences species diversity. Land use influences stream condition, and streams in poor condition are often wide, shallow, sediment‐laden channels with low instream habitat diversity. Our goal was to evaluate the effect of instream habitat diversity on fish species diversity, the effect of stream habitat condition on habitat diversity, and the effect of habitat diversity, stream condition, and other natural stream features on fish assemblage structure (proportional abundance) in an impaired upper Snake River basin watershed containing a locally diverse but regionally depauperate species pool. We sampled fishes and instream and riparian habitat at 41 sites, focusing on measures of instream habitat diversity and the following stream condition indicators: livestock trails on streambanks, streambank stability, channel width‐to‐depth ratio, percent fine substrates, and woody riparian vegetation. Multiple regression revealed that fish species diversity was positively associated with all four components of habitat diversity, that is, diversity in substrate, cover, water depth, and water velocity (P &lt; 0.09, adjusted R2 = 0.642). All four components of habitat diversity increased with stream size, and each component was negatively but weakly associated with at least one stream condition indicator (P &lt; 0.10, adjusted R2 = 0.23 to 0.61). Fish assemblage structure was influenced primarily by natural stream features (gradient, temperature) and secondarily by stream condition indicators and streamflow diversity. Our results connect fish species diversity increases in larger streams with concomitant increases in four dimensions of instream habitat diversity. The findings show how stream condition reflecting land uses, such as riparian over‐grazing, can negatively impact habitat diversity within that stream‐size continuum, thus emphasizing the role land management plays in maintaining fish species diversity.Received November 6, 2015; accepted February 20, 2016 Published online June 22, 2016

Habitat specialization and sensitivity to change in a threatened crayfish occupying upland streams

Abstract1. Crayfish are culturally and ecologically important species in freshwater ecosystems, but many are now threatened with extinction, due to threats such as habitat loss. Depending on their habitat selectivity and sensitivity, freshwater crayfish could provide effective targets for stream monitoring, restoration and conservation. This study used repeated field surveys of the threatened Murray crayfish, Euastacus armatus (family Parastacidae), to establish their habitat preferences and sensitivity to habitat loss across mesohabitat and microhabitat scales within upland streams of south‐east Australia.2. Selectivity analysis revealed that upland populations of E. armatus displayed a strong preference for areas of intermediate water flow velocity, deeper water, and stream beds dominated by boulders and gravel. Variations in E. armatus density among and within the two upland streams aligned with these microhabitat preferences, with best‐subsets analyses revealing that E. armatus abundance hotspots were best predicted by models combining water depth with percentage cover of boulders, gravel and overhanging riparian vegetation.3. Major shifts in stream habitat condition from 2009 to 2015 (e.g. 32% and 50% decline in boulder and overhanging vegetation cover, respectively) was associated with a 91% decline in E. armatus mean density within glide‐pool mesohabitats.4. These findings highlight how habitat specialization in threatened crayfish such as E. armatus may render them sensitive to changes in stream habitat condition, and how targeted monitoring, restoration and conservation of their preferred habitats could yield multiple benefits for montane freshwater ecosystems. Copyright © 2016 John Wiley &amp; Sons, Ltd.

Optimizing the operation of a hydraulic dam for ecological flow requirements of the You-shui River due to a hydropower station construction

River ecosystems are closely linked to flow velocity, depth, water temperature, and river bed substrates, and the alteration of hydrological regime due to dam operation has significant impacts on the river ecosystem. It is critical for river managers to seek the optimal solution to balance the environmental discharge requirement with hydropower production. This study investigated links between hydropower plant generation and stream habitat conditions in the You-shui River, China, and developed an optimization model to obtain the most beneficial solution for both generating capacity and environmental discharge. The typical annual flow rates were determined, and Chinese sucker (Procypris rabaudi) was chosen as the target fish with 4 life stages to represent the habitat suitability situation under the environmental discharge. The optimal model was designed to be a function of the maximum value of the sum of the power generating function and the overall suitability index (OSI) function. The traditional environmental flow scheme and optional plan with 3 other schemes were also calculated for comparison. The results of this model indicate that traditional environmental discharge methods cannot satisfy the requirement of juvenile, adult, and spawning stages of the target fish. The solution of the optional plan can meet the habitat demand but will significantly reduce the hydropower generation. The analysis indicates that the optimal model could well balance the hydropower production and the ecosystem protection in the You-shui River and is therefore recommended as a suitable dam management method.