Rural Watersheds Research Articles

Disposição de proprietários rurais à adoção de práticas voluntárias e compulsórias de restauração florestal na região do médio Rio Doce - MG

Abstract The maintenance of hydrological conditions in rural watersheds depends on the behavior of rural landowners regarding land use and vegetation cover protection. We analyzed the willingness of farmers from the Rio Doce basin to adopt voluntary forest restoration strategies and to bring their lands into compliance with Federal Law 12.651/2012. We applied a questionnaire to 30 landowners in the municipality of Governador Valadares and the surrounding region. The results indicate that 86% of the farmers acknowledge maintaining vegetation cover as highly important, highlighting benefits such as reduced erosion (86%) and increased discharge in springs (73%). Technical assistance for productivity (29.6%), donation of materials (22.2%) and economic incentives (22.2%) were identified as factors that increase the motivation of farmers to implement such practices. Agroforestry Systems were the most preferred modality (50%). The long-term presence of rural assistance organizations and the trust between them and landowners explain the dissemination of environmental notions and pro-conservation attitudes.

Phosphorus Export From Two Contrasting Rural Watersheds in the (Sub) Humid Ethiopian Highlands

Establishing worldwide sustainable and phosphorus efficient cropping systems is urgently needed because the supply of suitable phosphate rock is limited, and excess phosphorus in streams causes eutrophication. One of the impediments in the developing world for sustainable P practices is the lack of studies on P transport and its eventual disposition in the environment. One of these regions with few studies is the Ethiopian Highlands, with permeable volcanic soils. The objective was to establish baseline data on P watershed export in the (sub)humid highlands. Two contrasting watersheds were selected near Lake Tana. For 2 years, stream discharge and sediment, total P, dissolved P, and bioavailable particulate P concentrations were determined at the watershed outlet. The first watershed is the 57 km2 Dangishta, with lava intrusion dikes, forcing subsurface flow through faults to the surface and preventing gully formation. Subsurface flow was half of the 1745 mm annual precipitation, and surface runoff and erosion were minimal. The second watershed is the 9 km2 Robit Bata with 1,420 mm precipitation. The banks of several river banks were slumping. The upper part of the watershed generates saturation excess runoff. A hillslope aquifer in the lower part provided interflow. The average sediment concentrations of 10.5 g L−1 in the stream in Robit Bata (11 times that in Dangishta) reflected the sediments from banks slipping in the stream. The hydrology and the soil loss directly affected the phosphorus export. In Dangishta, the total P concentration averaged 0.5 mg L−1 at the outlet. In Robit Bata, the average total P concentration was 2 mg L−1. The bioavailable particulate P concentration was only twice the concentration in the runoff water. The low phosphorus content of the subsoil slipping in Robit Bata moderated biologically available particulate P at the outlet. Average dissolved P concentrations for both watersheds were around 0.1 mg L−1 in the low range found in temperate climates. It reflects the difference in length of time that phosphorus fertilizers have been applied. Our research concludes that commonly implemented practices such as strengthening river banks and stabilizing gully might not lead to improved water quality in Lake Tana.

Treatment try of simulated agricultural surface runoff pollution by using a novel biomass concentrator reactor

Increased agricultural surface runoff in rural watersheds is a leading cause of nonpoint source pollution. In this study, a new biomass concentrator reactor (BCR) is conducted to degrade simulated agricultural surface runoff for both start-up process and treatment process. The results show that both in the start-up phase and in the stable phase, BCR had a good degradation effect on simulated agricultural surface runoff. Within 13 days–15 days of completed start-up of BCR, degradation of COD can be considered to the first-order kinetics: lnCt=lnC0−0.1377t (R2 = 0.78). During the stabilization phase, the average removal rate of COD, NH4+-N, NO3−-N, TN and TP from the effluents through the BCR membrane was 94.58%, 85.79%, 53.58%, 37.87%, and 60.62%, respectively, which was increased by 7.4%, 2.5%, 5.1%, 0.18% and 11.4%, respectively, compared to control experiment which the effluents without membrane. The pollutants degradation by BCR in stable phase show a partly relative model of Lawrence-McCarty equation, which the nitrogen and phosphorus degradation is vN=(4.1+S)/(2.53×S) (R2 = 0.69) and vP=(8.78+S)/(3.0×S) (R2 = 0.67), respectively. In the stable phase, the operation cost of BCR is about $0.08/(L•d). Future research on improved BCR maybe focus on the membrane pollution and cleaning, optimized operation conditions, new materials of membrane.

No widespread signature of the COVID-19 quarantine period on water quality across a spectrum of coastal systems in the United States of America

During the recent COVID-19 related quarantine period, anecdotal evidence emerged pointing to a rapid, sharp improvement in water quality in some localities. Here we present results from an analysis of the impacts of the COVID-19 quarantine period using two long-term coastal water quality datasets. These datasets rely on sampling that operates at appropriate timescales to quantify the influence of reduced human activity on coastal water quality and span coastal ecosystems ranging from low human influence to highly urbanized systems. We tested two hypotheses: 1) reduced tourism during the COVID-19 quarantine period would lead to improved coastal water quality, and 2) water quality improvements would scale to the level of human influence, meaning that highly urbanized or tourist-centric watersheds would see greater improvement than more rural watersheds. A localized reduction in fecal indicator bacteria was observed in four highly impacted regions of the Texas (USA) coast, but this pattern was not widespread. In less impacted regions, the signature of natural, decadal environmental variability (e.g., dissolved oxygen and turbidity) overwhelmed any potential signature of reduced human activity. Results from this study add to the growing body of literature on the environmental impacts of the COVID-19 quarantine period, and when considered with existing literature, emphasize that coastal water quality improvements appear to be ephemeral and reserved for the most severely affected (by human activity) systems. Furthermore, results show the importance of assessing COVID-19 signatures against long-term, decadal datasets that adequately reveal a system's natural variation.

Location Matters: A Framework to Investigate the Spatial Characteristics of Distributed Flood Attenuation

Distributed attenuation in flood management relies on small and low-impact runoff attenuating features variously distributed within a catchment. Distributed systems of reservoirs, natural flood management, and green infrastructure are practical examples of distributed attenuation. The effectiveness of attenuating features lies in their ability to work in concert, by reducing and slowing runoff in strategic parts of the catchment, and desynchronizing flows. The spatial distribution of attenuating features plays an essential role in the process. This article proposes a framework to place features in a hydrologic network, group them into spatially distributed systems, and analyze their flood attenuation effects. The framework is applied to study distributed systems of reservoirs in a rural watershed in Iowa, USA. The results show that distributed attenuation can be an effective alternative to a single centralized flood mitigation approach. The different flow peak attenuation of considered distributed systems suggest that the spatial distribution of features significantly influences flood magnitude at the catchment scale. The proposed framework can be applied to examine the effectiveness of distributed attenuation, and its viability as a widespread flood attenuation strategy in different landscapes and at multiple scales.

TEMPERATURE-DRIVEN EVAPORATION ANALYSIS OVER BALLIKAYA CATCHMENT

Hydrometeorological analysis such as terrain characteristics, flood forecasts and water potentials have become possible through computer models today in parallel with rapidly ever-evolving technology. While the surface-runoff during a storm has linearly and highly correlation with effective precipitation, it is inversely proportional to hydrological losses, including interception, infiltration, transpiration and evaporation. However, flood estimation analysis, in especially rural areas in Turkey, is still not widely and accurately usable, due to difficulties in accessing the necessary ground-based data records such as evaporation, which affects much of the rainfall. Although direct measurement of evaporation is not available now, indirect methods such as evaporation pans have been developed to give acceptable results. On the one hand, observation networks are built by Turkish State Meteorological Service for the estimation of evaporation from open water bodies, these measurements, on the other hand, are only obtained at large climatological stations such as city centers and generally for only six months of the year. In this sense, evaporation values, in order to apply rainfall-runoff analysis, were estimated by Kharrufa, Blaney-Criddle, and modified Blaney-Criddle methods to be used in Monthly Average models. While the highest underestimations were obtained in modified Blaney-Criddle method, Kharrufa method outperformed the other Blaney-Criddle products. The results, confirmed by analysis of the temperature-based Kharrufa approach in two urban areas close to the study basin, show to be appliable for estimation of long-term hydrographs. The analyzed method can be applied over rural watersheds lacking in-situ evaporation measurements as well as enables more accurate rainfall-runoff simulations processes with calibrated and verified hydrological models.

Long-term analysis of road salt loading and transport in a rural drinking water reservoir watershed

Chloride exports from the widespread application of road salt serve as a primary contribution to water body salinity in cold climate regions. Road salt pollution is a concern in drinking water supplies due to the relationship between chloride concentration and water corrosivity. In the Northeastern U.S., researchers and water quality managers are interested in better understanding how management practices can mitigate the negative effects of road salt pollution. This study uses regression-based chloride load estimates from LOADEST to produce mass balances and analyze transport flow-paths to the Wachusett Reservoir from a predominantly rural watershed. A chloride mass balance for 2000 through 2019 revealed that reservoir and watershed export only recently reached a level similar to estimated inputs from road salt (11,200 ton/yr). Results from hydrograph and load separation techniques show that average loading (4300 ± 1300 ton/yr) and discharge from baseflow (3.2 ± 0.9 m3/s) contributed approximately 74% and 65% of the total loading (5800 ± 1800 ton/yr) and discharge (4.93 ± 1.50 m3/s), respectively from water years 2001 through 2019. Approximately 40% of the total annual tributary load (30% baseflow; 10% runoff) occurred in the spring (March–May) and is attributed to elevated baseflow conditions from snowmelt. As indicated by a baseflow chloride index, baseflow concentrations are 14% greater than the total concentrations measured in the tributaries. Therefore, the baseflow-dominated tributary chloride loading is due to a combination of greater discharge and chloride concentration in baseflow as compared to direct surface runoff. However, a long-term trend analysis suggests a slightly increased fraction of chloride loading via overland flow in several reservoir tributaries, potentially indicative of late 20th century land development. This study offers a unique monitoring approach for management authorities to better assess road salt pollution in water systems. The decadal response of the reservoir system reflects the slow-moving nature of the baseflow-dominated chloride loading and suggests that measurable water quality improvements will only be realized with a sustained long-term decrease in the amount of road salt applied.

Degree of Anthropogenic Land Disturbance Controls Fluvial Sediment Hysteresis.

Storm events dominate sediment delivery to stream corridors, but the effects of anthropogenic disturbances on altering the sources, pathways, and timing of delivery remain uncertain. To address this knowledge gap, we analyzed 849 events from over a decade of high-frequency turbidity data across five watersheds in an urbanization gradient. Sensing results suggested that hysteresis patterns evolved with land use from clockwise (low-rural) to figure-eight (high-rural) to counter-clockwise (high-urban), indicating a disturbance-driven shift of sediment provenance from proximal to distal. Sediment loading pathways in the lowest-disturbance rural watershed were dominated by a single hysteresis shape (>90% of export by clockwise events), whereas the most-disturbed urban basin had the greatest variability in loading pathways (∼25% of export by clockwise, counter-clockwise, figure-eight, and complex events, respectively). Finally, wastewater treatment facilities modulated the release of "hungry-water" baseflow, causing more-rapid periods of high streamflow variance in catchments with a treatment facility (∼4 h period) than in those without (∼6 h period). Together, our results indicate that anthropogenic disturbances, including tile drainage, impervious surfaces, and roadway density, increase the connectivity of distally located sediment that would-in undisturbed basins-deposit along the sediment cascade. This information is important to watershed managers as they mitigate erosion in developing basins.

Factors Influencing Water Quality Perceptions in an Urban and Rural Watershed in Southern Ecuador

River water quality and quantity are declining globally as a result of land use and population growth. Enhanced river management that includes input from local watershed residents is needed to sustain this resource. As an international framework, integrated water resources management (IWRM) aims to support inclusive governance of water systems. Ecuador is one of the countries that has looked to IWRM as a guide, though little research on water quality is available in the country. Our case study describes both the research process and outcomes of an integrated assessment of water quality and perceptions in the south Ecuador city of Loja, through which flow two rivers: Rio Zamora and Rio Malacatos. Our team sought to take both biophysical and perceptual measures of water quality in these rivers and tributaries and build interdisciplinary research skills among undergraduate and early graduate students in collaboration with faculty researchers from the Universidad Técnica Particular de Loja and the University of Idaho. In this case article, we concentrate on the process and results of the social scientific dimension of this interdisciplinary project, describing how surveys and interviews were used to build our understanding of the connections between the biophysical water quality measures and water quality perceptions of different communities within the watershed. Readers will learn about the possibilities of conducting interdisciplinary, international team projects to answer applied socioenvironmental questions along with challenges that should be anticipated when designing this kind of research.

Intra‐annual variability of urban effects on streamflow

AbstractWhile considerable research has established the impacts of urbanization on streamflow, there has been little emphasis on how intra‐annual variations in streamflow can deepen the understanding of hydrological processes in urban watersheds. This study fills this critical research gap by examining, at the monthly scale, correlations between land‐cover and streamflow, differences in streamflow metrics between urban and rural watersheds, and the potential for the inflow and infiltration (I&I) of extraneous water into sewers to reduce streamflow. We use data from 90 watersheds in the Atlanta, GA region over the 2013–2019 period to accomplish our objectives. Similar to other urban areas in temperate climates, Atlanta has a soil‐water surplus in winter and a soil‐water deficit in summer. Our results show urban watersheds have less streamflow seasonality than do rural watersheds. Compared to rural watersheds, urban watersheds have a much larger frequency of high‐flow days during July–October. This is caused by increased impervious cover decreasing the importance of antecedent soil moisture in producing runoff. Urban watersheds have lower baseflows than rural watersheds during December–April but have baseflows equal to or larger than baseflows in rural watersheds during July–October. Intra‐annual variations in effluent data from wastewater treatment plants provide evidence that I&I is a major cause of the relatively low baseflows during December–April. The relatively high baseflows in urban watersheds during July–October are likely caused by reduced evapotranspiration and the inflow of municipal water. The above seasonal aspects of urban effects on streamflow should be applicable to most urban watersheds with temperate climates.

MAXIMUM FLOW STUDY BY THE HYDROGRAM METHOD FOR A WATERSHED IN THE SOUTH OF SANTA CATARINA, BRAZIL

Knowing the maximum flow and its return period is extremely important for safely dimension hydraulic projects for flood prediction and control and also water erosion prediction. Thus, this study aimed to evaluate Capivari river watershed maximum flow, located in south of Santa Catarina, that has a flooding history. The method used was The United States Soil Conservation Service (SCS) Triangular Unit Hydrogram method (current Natural Resources Conservation Service), and, for effective rainfall, the US Curve Number (SCS-CN) method is used. To estimate the maximum flow in the watershed, three background moisture scenarios (CNI, CNII and CNIII) and six empirical equations proposed for rural watersheds were adopted to calculate the concentration time. To evaluate the observed upstream flow, a 34-years historical series was used, measured at the São Martinho downstream fluviometric station (code 84598002), located in the outlet section of the study watershed. The results showed that the maximum flows estimated by the SCS-CN method for the conditions of CNII and CNIII had greater differences (-198% and -287%) compared to the observed flow. The smallest differences were verified for the CNI condition for all the analyzed return periods (2, 5, 10, 15, 20, 25, 50 and 100). Also, it was observed that, the longer is the return period, smaller the difference among the maximum observed and estimated flows, and, the smallest was verified for the 50-year period, indicating that this is the most appropriate for studies of extreme events in the study watershed.

Multi-Criteria Hydro-Economic Decision Tool for Rejuvenating Community Irrigation Tanks in Rural India

Rising water scarcity in agriculture has been a major concern worldwide. As resource managers seek to address this issue, Integrated Water Resources Management (IWRM) has become a widely accepted sustainability paradigm. The purpose of this study is to evaluate restoration alternatives of irrigation tanks by applying multi-criteria and probabilistic benefit–cost analysis for a rural watershed in India. We incorporate the principles of local-IWRM, namely, hydrological balance, efficiency, equity, stakeholders’ involvement, and uncertainty. We use the mixed-method approach of data collection, including remotely sensed hydro-ecological data, walk-through field observations, focus groups, and household surveys. The study region produces a large percent of runoff water (i.e., about 67% of the total precipitation) which can be partially captured to sustain irrigation tanks. The majority of the tanks in the study area do possess moderate to high irrigation potential yet remain in poor conditions. A proposed lift irrigation scheme with a 75% or more increase in water availability could return from ₹ 1.23 to ₹ 1.73 on every Indian rupee (₹) invested, in addition to other socio-ecological benefits. The increase in water availability could lead to future crop area expansion, which comes with a high price tag. Therefore, using additional water on the existing crop area can be just as economically viable as water-induced crop expansion. A coordinated effort on the part of local agencies and water users is necessary for efficient and equitable use of incremental water that comes from any restoration efforts in the study area or elsewhere.

Soil properties characterization for land-use planning and soil management in watersheds under family farming

Environmental monitoring of small, rural watersheds was one of the components of the Natural Resources Management and Rural Poverty Alleviation Program (RS-Rural) in southern Brazil. The purpose of the monitoring was to assess the impact of promoting soil conservation and environment management practices adopted by farmers and funded by the Program. In four small monitored watersheds, in a total of 95 plots representing distinct land use and soil management, surface soil was collected to characterize ground-zero of the Program by determining several soil physical, chemical and microbiological properties. Principal component analysis (PCA) shows soil physical, chemical and biological properties were decisive in defining the agricultural soils in the rural watersheds with family farming. The sensitivity to chemical properties provides an opportunity to improve soil quality if soil management focuses on altering those properties. Soil management practiced by tobacco farmers leads to rapid, intense degradation of some natural soil properties, especially those related to the dynamics of soil organic matter, compared with more conservationist uses (forest, regrowth, and grassland). Thus, soil management must be reoriented to avoid the progress of degradation and recover soil physical and biological quality. Cover crops and by land-abandonment to allow natural vegetation are important management strategies for the degraded soils used for tobacco production, increasing soil organic matter, nutrients and microbial activity and thus allowing further crop production. In conclusion, watersheds with tobacco cropping have soils with lower quality than when under no-tillage grain production, requiring changes in land use and soil management.

Applying a novel framework for the estimation of the full cost of water in a degraded rural watershed

Abstract Water Resources Management's modern concerns include solutions on water scarcity, water quality problems and the use of economic and decision-support tools. Especially, the agricultural sector in South Europe under the requirements of the Water Framework Directive 2000/60/EC(WFD) remains a challenge. Most scholars so far doubt and criticize the implementation of the full cost of irrigation water, review papers highlight the limited progress, and fewer cases provide guidance on how to address this case. The present study applies a novel methodological framework for the estimation of the full cost of irrigation water, based on hydro-economic concepts such as: water balance, profits from agriculture, water value, water quality, monetary, opportunity and environmental costs. Originally, the method has been applied only once in a rural watershed with surface and groundwater resources. Here, a degraded Greek watershed using only groundwater resources is the study area, and the results of the two cases are compared. The model was also examined under demand management strategies and recommendations to scrutinize the effects and the applicability of the proposed measures in hydrological and economic terms. The findings give useful insights on the future management of achieving economic objectives with environmental constraints and the harmonization of Greek agriculture to the WFD.

Streamflow simulation in data-scarce basins using Bayesian and physics-informed machine learning models

AbstractHydrologic predictions at rural watersheds are important but also challenging due to data shortage. Long Short-TermMemory (LSTM) networks are a promising machine learning approach and have demonstrated good performance in streamflow predictions. However, due to its data-hungry nature, most of LSTM applications focused on well-monitored catchments with abundant and high quality observations. In this work, we investigate predictive capabilities of LSTM in poorly monitored watersheds with short observation records. To address three main challenges of LSTM applications in data-scarce locations, i.e., overfitting, uncertainty quantification (UQ), and out-of-distribution prediction, we evaluate different regularization techniques to prevent overfitting, apply a Bayesian LSTM for UQ, and introduce a physics-informed hybrid LSTM to enhance out-of-distribution prediction. Through case studies in two diverse sets of catchments with and without snow influence, we demonstrate that: (1) when hydrologic variability in the prediction period is similar to the calibration period, LSTM models can reasonably predict daily streamflow with Nash-Sutcliffe efficiency above 0.8, even with only two years of calibration data. (2) When the hydrologic variability in the prediction and calibration periods is dramatically different, LSTM alone does not predict well, but the hybrid model can improve the out-of-distribution prediction with acceptable generalization accuracy. (3) L2 norm penalty and dropout can mitigate overfitting, and Bayesian and hybrid LSTM have no overfitting. (4) Bayesian LSTM provides useful uncertainty information to improve prediction understanding and credibility. These insights have vital implications for streamflow simulation in watersheds where data quality and availability are a critical issue.

Combining narrative scenarios, local knowledge and land-use change modelling for integrating soil erosion in a global perspective

Mediterranean soil resources are heavily affected by water erosion. There is a need for anticipating the potential impact of land-use change at the catchment scale, considering a range of contrasted possible changes, in order to prepare a relevant adaptation strategy. While participatory scenario approaches are useful for unveiling the diversity of possible futures, their outputs generally take the form of narratives that may be difficult to relate to biophysical models used for simulating soil and water processes. We addressed this challenge by developing a methodology combining narrative scenarios and land-use change modelling at the catchment scale, interacting with local stakeholders who were involved throughout the research, in line with current Land System research. First, we built contrasted scenarios, each with a narrative story and quantitative assumptions for key variables. Then we drew up rules for translating narrative scenarios into spatially explicit maps based on expert groups and local knowledge, simulating the evolution of land use over time. Third, we evaluated and validated the final scenarios by conducting two workshops with scientists and local stakeholders. Finally, we assessed the impact of these scenarios on agricultural production and erosion control. This approach was implemented in the Tleta basin (Morocco), a 180 km2 rural watershed, 10 km from Tangiers and heavily affected by water erosion. As a result, we propose three contrasted spatially explicit land-use change scenarios by 2040. Our work highlights the interest of combining narrative storylines and land-use modelling when developing spatially explicit scenarios at the catchment scale, incorporating the local knowledge of stakeholders. The combination of Land System and ecosystem frameworks contributes to integrating the soil erosion issue in a more global perspective, and lays the foundation for building sustainable strategies for Mediterranean catchments affected by soil erosion.

Water Resources Management: Green Watershed Index (GWI)

A large number of indices and indicators of water performance at the basin level exist throughout the world, however, the need to generate tools that allow the monitoring of basins from their administration and water and environmental management, takes greater force in a global context where sustainability takes great importance. The GWI (green watershed index) methodology is presented, as an extension of urban control methodologies, but this time for rural watersheds. The method is implemented in some rural areas of Colombia, and in some cases the difficulty of implementing the methodology is evidenced, and in other cases the opportunity to improve the management and administration of water resources at the level of rural basins.

Selection of a Hydrological Model and Objective Function for Water Resources Management in Predominantly Rural Watershed using Criteria-Based Evaluation

Selection of a fitting up-to-date hydrological model using an evaluation of the functionality, modeler’s requirements, and modeling experiences are very important for water resources management in rural watersheds. Similarly, the selection of appropriate objective function is equally crucial in hydrological modeling processes. Accordingly, A review study was carried to select an appropriate model and objective function for water resources modeling in the predominantly rural watershed. Hydrological models namely HEC-HMS, MIKE SHE, SWAT, TOPMODEL, and SWMM, and objective functions namely NSE, RMSE, MRAE, and RAEM were reviewed. Hydrological models were reviewed under several criteria viz. temporal scale, spatial scale, hydrological processes, documentation, resources requirement, user interface and, model acquisition cost. Whereas, criteria for the review of objective functions were mathematical implication, flow regime, and modeling purpose. Each of the review criteria was comprised of several factors. The criteria-based evaluation was done to quantify the review outcome of the hydrological model and objective function. SWMM was found to be the most suitable model for simulating rural watersheds for water resources management purposes whereas, MRAE was found to be the most appropriate objective function to evaluate the performance of the model selected for rural watershed modeling.

Precipitation-induced transport and phase partitioning of organophosphate esters (OPEs) in urban and rural watersheds

Particle-bound OPEs were observed at fractions higher than expected based on predicted partitioning behaviour, i.e. organic carbon–water partitioning ratios (log ) calculated from field data were generally higher than predicted values.

Microfiber Content in Freshwater Mussels from Rural Tributaries of the Saint John River, Canada

Microfibers are now ubiquitous in the environment largely due to the widespread use of natural and synthetic textiles. Many enter aquatic systems through wastewater treatment plant (WWTP) effluent, surface water runoff, and atmospheric deposition, where they persist and may be ingested by filter-feeding organisms. In addition to causing physical damage (e.g., digestive and respiratory obstructions), microfibers are often carriers of chemical pollutants that may also harm biota. This exploratory study aimed to determine whether freshwater mussel (Margaritifera margaritifera L.) microfiber content varied between two rural tributaries of the Saint John River, whether microfiber content was related to WWTP discharge points or potential diffuse microfiber sources, and whether mussel size was associated with microfiber content. Mussels were collected both upstream and downstream of five WWTP discharge points and at 11 other points along two rivers within rural watersheds of maritime Canada. Microfiber content differed significantly between the two rivers; however, no trends were observed in microfiber content in relation to WWTP discharge points on either river. Smaller mussels contained significantly more microfibers than larger mussels, despite differences in mussel size ranges between tributaries. These results reveal a potential pathway for microfibers to enter aquatic food webs and highlight important implications for the use of freshwater mussels as bioindicators of microfiber contamination.