Riparian buffers in agricultural landscapes are designed to trap pollutants in overland flow by slowing, filtering, and infiltrating surface runoff entering the buffer via sheet flow. However, observational evidence suggests that concentrated flow is prevalent from agricultural fields. Also, over time sediment can accumulate in riparian buffers forming berms that restrict sheet flow from moving into the buffers; these berms ultimately back up surface runoff, resulting in an eventual breakthrough which concentrates runoff. Breakthrough by concentrated flow can lead to gully formation that may reduce the filtering capacities of buffer systems by providing direct conduits to stream channels. This study explores the frequency of concentrated flow paths in riparian buffers at both the field and watershed scale. At the field scale, intensive topographic surveys were conducted at 10 field sites in southern Illinois to characterize concentrated flow paths, accumulated berm sediments, and field area drained by concentrated flow. Detailed digital elevation models (DEMs) were created for each site and riparian buffer and agriculture field characteristics were analyzed to assess the development and occurrence of concentrated flow paths. At each site, soil samples were analyzed to characterize sediment deposition patterns within the buffer. To assess the prevalence of concentrated flow paths at the watershed scale, three watersheds in southern Illinois were selected for walking stream surveys. Five stream segments, approximately 1000 m long, were randomly selected within each watershed and surveyed for the occurrence and size of concentrated flow paths. These data were analyzed with respect to riparian buffer vegetation, buffer width, and surrounding land cover data. Concentrated flow paths were identified in all topographic surveys and all walking stream surveys indicating a common occurrence in agricultural watersheds of southern Illinois. Among field scale sites, concentrated flow accounted for 82.5-100% of the drainage areas contributing to riparian buffers. Results from the watershed scale analysis suggest that concentrated flow paths are significantly more abundant in agricultural land cover, than forested land. Current riparian buffer design principles are based on the assumption that sheet flow is the primary form of surface runoff entering buffers. Furthermore, buffers are installed and not maintained which can lead to berm accumulation and buffer failure. Results from this study indicate that concentrated flow was the prevalent form of runoff at field scale sites. Managers need to consider the occurrence of concentrated flow paths when designing riparian buffers to protect stream water quality.

Seasonal hypoxia in the northern Gulf of Mexico has been mapped extensively and is known to overlap the habitat of the brown shrimp Farfantepenaeus aztecus on the Louisiana continental shelf. Yet the impacts of Gulf hypoxia on the profitable brown shrimp fishery in Louisiana remain largely unknown. The problem is primarily attributable to nonpoint source pollution in the Mississippi River, but awareness of the problem has not resulted in an effective policy solution to stem this pollution to date. Using the combination of a quantitative data analysis to look for a correlation between Farfantepenaeus aztecus and hypoxic water, a survey mailed to shrimp fishers in Louisiana, and qualitative interviews with shrimp fishers and environmental activists and lawyers in Louisiana, I will examine the potential of a legal tool, the Public Trust doctrine, to slow nonpoint source pollution into the Mississippi River.

A redução dos impactos da poluição difusa é ainda pouco explorada no Brasil, havendo ausência de critérios legais quanto à sua mitigação. Contudo, na esfera científica o seu impacto é reconhecido. Seguindo evidências de que há uma carência no tratamento de poluição difusa no país, este trabalho se propõe a analisar wetlands construídas como medidas de controle de poluição difusa, através de modelagens, para 4 áreas na bacia do córrego do Mineirinho. A exploração dessa proposta se deu por três abordagens paralelas. Na primeira, as wetlands foram projetadas para tratar o escoamento superficial de uma chuva crítica, de 61 minutos. Na segunda abordagem, foi utilizada uma chuva crítica de 24 horas de duração. Na terceira, utilizou-se o índice de precipitação anual. O escoamento superficial foi calculado conforme os coeficientes de runoff. Atribuíram-se valores de concentrações médias de evento para DBO e Fósforo aos tipos de uso e ocupação, obtendo-se concentrações médias nas águas pluviais a serem tratadas. O modelo P-k-C* foi empregado na primeira e terceira abordagens, para dimensionar os sistemas com base no desempenho de remoção de cargas. Os resultados obtidos demonstraram a aptidão dos sistemas em reduzir cargas e/ou concentrações na bacia, apresentando como principal limitação técnica o espaço demandado para sua implantação. Houve influência majoritária da infiltração na remoção de cargas, que agiu em conjunto com o decaimento de poluentes ao longo dos sistemas. Na primeira abordagem, o modelo P-k-C* apresentou limitações em prever o desempenho dos sistemas por não comportar vazões variáveis. A segunda abordagem foi a mais simples, baseada apenas no armazenamento do evento crítico, entretanto, há uma carência de relações empíricas traçadas experimentalmente para prever seu desempenho. A terceira abordagem se mostrou a mais adequada ao modelo P-k-C*, podendo ser aprimorada de duas formas: adaptações nas constantes cinéticas ou vazões equivalentes, a fim de descrever uma média anual de desempenho. Concluiu-se que wetlands construídas demonstram potencial para o tratamento de poluição difusa, porém há uma necessidade de estudos a fim de se adaptar as ferramentas de modelagem disponíveis. / Nonpoint source pollutions impacts are still a rarely explored theme in Brazil, in which there are no legal criteria for its treatment. Although, in the scientific sphere its impacts are well known. Following evidence that there is a lack of nonpoint source pollution treatment in Brazil, this study proposes to analyze constructed wetlands as a nonpoint source pollution control measure, through modelling, for four different areas in the Mineirinho stream watershed. This proposal was explored through three different approaches. At first, the wetlands were designed to threat a critic rainfall for flood estimation, with detailed hydrographs. On the second approach, the wetlands were design to fully contain a 24-hour critic rainfall. On the third approach, the wetlands were designed to treat the average annual rainfall. The runoff volumes were estimated by runoff coefficients, and event mean concentrations for BOD and TP were assigned to each source area, resulting in the stormwater quality estimation. The P-k-C* model was applied to calculate systems performance on the first and third approaches. The results showed the aptitude of the systems for reducing loads and concentrations in the watershed, although mainly limited by the availability of areas. Infiltration had a major hole in reducing loads, although there were also significant amounts of pollutant removed by the systems. At the first approach, the P-k-C* model presented limitations on describing stormwater treatment, because of its unsteady and intermittent characteristics. The second approach was the simplest, based on containing the whole runoff volume, but it also showed a lack of studies stablishing empiric relations to estimate its performance. The third approach was the most adequate to the P-k-C* model, which usage could be improved by two adaptations in its parameters: kinetic coefficient adaptations or the adoption of equivalent steady flows, to describe the annual wetland performance. The study concluded that constructed wetlands show great promise for treating nonpoint source pollution in the watershed, but there is a need of more studies to regionalize empiric solutions available in the scientific literature, to apply the designing techniques with greater precision.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Economic development and growth of productive activities have been accelerating the degradation of water resources. This research aimed to evaluate the pollutant loads in surface waters and in sediments conveyed by urban drainage systems in a tributary of the Cadena creek in the municipality of Santa Maria-RS. A number of factors may interfere with the water pollution, such as precipitation, stream flow, use and occupation of the land area of the basin, and dry period prior to the event. Results showed that the mean concentration of events presented a variability related to precipitation and precipitation intensity. The average concentration of pollutants in the events tended to increase with the precipitation and precipitation intensity. The prior dry period was significantly correlated with the heavy metals copper and nickel. Diffuse load obtained for total suspended solids, BOD and total coliform organisms was 28.812 kg/ha/year, 3.225 kg/ha/year and 5,03E+07 organisms/ha/year, respectively. The curves M(V) along with the curves of maximum divergence evidenced the variability of the first flush and the differences between the events and parameters. The difference in the pollutant load is due to the high degradation process because of anthropogenic activities, such as urbanization and launch of domestic wastewater. Concentrations of heavy metals in bottom and suspended sediments were below the limit established by CONAMA Resolution 454/12 and the guidelines of the sediments of the Environment Institute of Canada. The bed material of the Cancela-Tamandaí creek is sandy with a predominance of coarse and medium sand. / O desenvolvimento econômico e o crescimento das atividades produtivas vêm acelerando o processo de degradação dos recursos hídricos. Esta pesquisa teve como objetivo avaliar as cargas de poluentes nas águas superficiais e nos sedimentos veiculados pela rede de drenagem urbana, em um afluente do arroio Cadena, no município de Santa Maria-RS. Obtendo-se uma análise dos fatores que interferem na poluição do curso hídrico como: precipitação, vazões, uso e ocupação do solo, área da bacia e período seco antecedente ao evento. As concentrações médias dos eventos tiveram variabilidade em função da precipitação e da intensidade da precipitação. A concentração média dos poluentes nos eventos mostrou tendência a aumentar com a precipitação e com a intensidade de precipitação. O período seco antecedente apresentou correlação significativa com os metais pesados cobre e níquel. A carga difusa obtida para sólidos suspensos totais foi de 28.812 kg/ha/ano, para DBO de 3.225 kg/ha/ano e para coliformes totais de 5,03E+07 organismos/ha/ano. As curvas M(V), juntamente com as curvas de máxima divergência evidenciaram a variabilidade da carga de lavagem e as diferenças entre os eventos e parâmetros. A diferença na carga poluente deve-se ao processo de degradação elevada devido às atividades antrópicas, como urbanização e lançamento de efluente doméstico. As concentrações de metais pesados nos sedimentos de fundo e em suspensão apresentaram-se abaixo do limite estabelecido na resolução CONAMA nº 454/12 e nas diretrizes de sedimentos do Instituto do Meio Ambiente do Canadá. O material de leito do arroio Cancela-Tamandaí é arenoso, com predomínio de areia grossa e areia média.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / This paper aimed to quantify pollutants connected to sediments of different sizes in impermeable surfaces in three sampling campaigns. Dry sediments collections were dane on Marquês do Herval ad Rigoberto Duarte streets, both located on the Cancela Creek basin in Santa Maria county, RS, as well as hidrosedimental monitoring at the drainage system escape on Marquês do Herval St. Dry sediments samples prior to rainfall, as well as surface runoff sediment samples during rainfall, were separated into 4 granulometric bands (≤63μm, 63-250μm, 250-500μm e ≥500μm). Organic pollution, nutrient and heavy metal contents were evaluated for each granulometric band by determining the concentration of the following parameters: oxygen chemical demand, ammonia, nitrite, nitrate, phosphate, sulphate, chloride, fluoride, copper, nickel, zinc and lead. Granulometry lower than 63μm represented on average 2,6% of the total sediment content for Marquês do Herval St. and 3,5% for Rigoberto Duarte St. Granulometry above 250μm represented on average 70% of the sediment content for both streets. Heavy metal samples showed higher concentrations in granulometry below 63μm. In dry sediment samples, the highest sulphate, phosphate and chloride contents were found in granulometry above 500μm. Ammmonia, nitrate, lead and zinc are associated with the 63-250μm granulometric band. / Este trabalho teve como objetivo quantificar os poluentes ligados aos diversos tamanhos de sedimentos em superfícies impermeáveis em três campanhas de amostragem. Foram realizadas coletas de sedimento seco nas ruas Marquês do Herval e Rigoberto Duarte, ambas localizadas na bacia do arroio Cancela no município de Santa Maria-RS; e monitoramento hidrossedimentológico na saída da canalização da rua Marquês do Herval. As amostras de sedimento seco dos dias anteriores a precipitação, bem como as de sedimento ligado ao escoamento superficial, durante a precipitação, foram separadas em 4 faixas granulométricas (≤63μm, 63-250μm, 250-500μm e ≥500μm). Para cada faixa granulométrica foi avaliada a carga de poluição orgânica, de nutrientes e de metais pesados, através da determinação das concentrações dos seguintes parâmetros: demanda química de oxigênio, amônia, nitrito, nitrato, fosfato, sulfato, cloreto, fluoreto, cobre, níquel, zinco e chumbo. A granulometria menor que 63μm representa em média 2,6% da carga total de sedimentos para a rua Marquês do Herval e 3,5% para a rua Rigoberto Duarte. A granulometria maior que 250μm representa em média 70% da carga de sedimentos em ambas as ruas. As amostras de metais pesados apresentaram maiores concentrações na granulometria menor que 63Sm. Nas amostras de sedimento seco, as maiores cargas de DQO, sulfato, fosfato e cloreto foram encontradas na granulometria maior que 500μm. A amônia e o nitrato, chumbo e zinco estão associados a faixa granulométrica de 63-250μm.

<p>A survey of farmers was conducted to determine the extent of cost-share and non-costshare BMP implementation and to evaluate the impact of socio-economic variables of the adoption of BMPs in Virginia's Chesapeake Bay drainage basin. Farmers in 67 counties in Virginia were randomly selected using VirGIS land use data and GRASS 4.1. All of the counties included in the study had at least 90 percent of their total land in the Chesapeake Bay drainage basin. Surveys were mailed to approximately 5,850 farm operators and 1,377 responses were returned, with approximately 1,099 estimated to farm in the Chesapeake Bay basin.</p> <p> A concern for pollution in the Chesapeake Bay was evident by farmers throughout the Bay basin, as 80 percent of the respondents indicated being concerned about water pollution in the Chesapeake Bay. However, only 33 percent believed that their farm contributed to water quality problems. The most often indicated perceived causes of pollution were runoff from urban or paved areas, industrial waste or factory discharge, sewer systems, and litter or garbage.</p> / Master of Science

This study discusses the monitoring requirements of an effluent credit trading system that allows point source discharges to purchase effluent reductions by financing agricultural nonpoint source best management practices. It describes the results of a national survey of existing trading programs that assessed how each program determines nonpoint source baseline pollutant discharges, pollutant reductions attributable to best management practices, verification of best management practice(s) installation and maintenance activities, and how often this verification is performed. This study surveyed the nonpoint source discharge monitoring programs of several of the successful effluent credit trading systems in the U.S. It documents and discusses specific characteristics of nonpoint source pollutant discharge monitoring strategies. Finally, this thesis compares trading program discharge monitoring characteristics to the current Virginia Cost-Share nonpoint source monitoring program. The goal of this study is to recommend elements of a nonpoint source discharge monitoring strategy to the Commonwealth of Virginia that can be used in a trading program of its own. The study shows that the majority of existing effluent credit trading programs use watershed models and land use evaluation algorithms to indirectly monitor nonpoint source pollutant discharges on a watershed basis rather than relying on empirical sampling and analysis activities for individual farms of fields. Monitoring takes a variety of forms to provide the diverse information necessary to indirectly determine nonpoint source discharges. Most trading programs monitoring strategies are no more comprehensive than agricultural cost-share programs even though many stakeholders believe that a trading program's monitoring activities should be exact enough to determine contributions from individual nonpoint sources to support the payments for individual activities. This objection is a barrier to the acceptance of trading programs by the public. A Virginia trading program must enhance its agricultural best management practice cost-share program monitoring practices to track nonpoint source discharges from individual farms or fields to be accepted and successful. / Master of Engineering

Monitoring of a regional stormwater management facility, located on the Virginia Tech campus in Blacksburg VA, was conducted in order to assess its efficacy in reducing nonpoint source pollutant losses downstream. The facility design includes both an upper water quality (wet) pond and a lower 100-yr-event quantity (dry) pond. These on-stream ponds capture both baseflow and storm runoff from the southern portion of the Virginia Tech campus and surrounding lands, and release the water back to the unnamed stream shortly above its conjunction with Stroubles Creek, a tributary of the New River. Monitoring sites for flow measurement, water quality sampling, and biotic assessments (habitat evaluation and rapid bioassessment of benthic macroinvertebrates) were located above and below each of the ponds. Both grab samples and automated samples were collected at these stations. Between 1997 and 1999, water quality grab samples included 35 baseflow samples and 22 stormflow samples. The grab samples were analyzed for concentrations of total suspended solids (TSS), metals, bacteria, and nutrients as well as temperature, pH, dissolved oxygen, conductivity, total organic carbon (TOC), and chemical oxygen demand (COD). Automated flow-weighted sampling was initiated in February of 1999 and results are reported through the end of October 1999. Thirty-three storms in 1999 were monitored for flow and various water quality parameters (TSS, TOC, COD, and nutrients). Pollutant loads and pollutant removal estimates were calculated with regard to the wet pond, dry pond, and the combined facility. Two types of pollutant removal efficiencies were calculated: (1) the EMC efficiency, based on pollutant concentrations from individual storms; and (2) the SOL efficiency, based on pollutant loads, to estimate long-term performance over the study period. Benthic macroinvertebrate sampling and habitat assessment were performed in both 1997 and 1999. In addition, a preliminary investigation of pond characteristics was conducted, including measurements of water quality and composition, sediment deposition and composition, and residence time. As a system, the stormwater management facility appears to have minimum impact on improving the downstream water quality. Pollutant concentrations and loads both appear to increase downstream of the facility as compared to upstream, during both storm event and baseflow periods. Monitoring results of the benthic assemblages showed evidence of moderate to high impairment at all sampling locations, and habitat assessments showed evidence of high sedimentation levels within the stream, even after installation of the stormwater management facility. Total suspended solids (TSS) concentration removal efficiency was 10% for the combined wet pond and dry pond system, much lower than the 80 to 90% TSS removal expected for properly functioning stormwater management facilities (Hartigan, 1989). There is some evidence of sedimentation within the ponds because of a slight reduction in sediment-bound constituent export, but the dissolved nutrient constituents had either very low and most often negative (indicating pollutant export) removal efficiencies. Concentrations of metals measured in the stream often exceeded their respective acute and chronic water quality criteria at all sampling locations. Pollutant removal efficiencies measured in the wet pond are atypical of those reported in the literature (Schueler, 1993). Insufficient residence time (two days compared to the optimal two weeks), and wet pond embankment failure are likely the principal causes of the wet pond's inadequate performance and thus, the inadequate performance of the overall facility. TSS removal efficiencies were low in the wet pond (19% for concentrations and 33% for loads) compared to the 80 to 90% expected for similar ponds. Nevertheless, the wet pond reduced the concentrations of several pollutants typically associated with TSS and not likely to be associated with the fill material for the wet pond embankment. Zinc concentrations in sediment cores were highest near the pond inlet, where the majority of sedimentation occurs. During storm events, the following results were noted. Copper and zinc concentrations in 1998 were lower at the pond outlet as compared to the pond inlet, and TOC concentrations and loads were also reduced by the wet pond (13% for concentrations and 12% for loads). However, sedimentation is also expected to remove phosphorusl, and wet pond phosphorus loads were only reduced by 10% and 3% for orthophosphorus and total phosphorus, respectively. Because the wet pond is undersized with respect to the watershed it serves (surface area less than 1% of the watershed area (0.87 ha), as compared to the 3% ratio often recommended for optimal pollutant removal (Athanas, 1988)), higher removal efficiencies were found during baseflow periods. The greatest reductions in baseflow concentrations were for ammonia (67%), nitrate (57%), total nitrogen (54%), and COD (45%). However, the residence time of two days appears to be insufficient to reduce fecal coliform concentrations in the stream, and over 40% of the fecal coliform samples collected exceeded the water quality standard for contact recreation (DEQ-WQS, 1997). Furthermore, the wet pond did not appear to reduce TSS or TOC during baseflow periods. Export of TSS (-29% EMC efficiency) and TOC (-44% EMC efficiency) from the wet pond during baseflow periods is likely due to the wet pond embankment failure as well as pond eutrophication. Eutrophication processes are favored by the water temperature increase as flow passes through the shallow wet pond. The wet pond increased downstream temperatures by approximately 8°C above inflow temperatures during the summer, and to levels above 21°C which cannot be tolerated by sensitive coldwater species (Schueler, 1987). The dry pond did not remove dissolved nutrient constituents or other pollutants during baseflow periods, but there is some evidence of sedimentation within the dry pond during storm events. During storm events, the dry pond was effective in removing TSS, with a concentration removal efficiency of 69% (EMC efficiency) and loading removal efficiency of 43% (SOL Efficiency). Removal of TKN and total phosphorus (36% and 37% respectively for concentrations) within the dry pond is further evidence of sedimentation within the dry pond. The wet pond embankment was built in 1997, and monitoring occurred during a potential stabilization period when evidence of water quality benefits are slow to appear, especially with respect to downstream habitat and aquatic communities. Some benefits which could have been observed more immediately may have been negated or masked by the progressive erosion of the wet pond embankment as a result of a design flaw. Further complicating the results is the appearance; based on observations of extended drawdown time and results from a water budget analysis in the wet pond (where inflow substantially exceeds inflow); that groundwater interacts with the pond in a complicated fashion, possibly including both recharge and discharge. To fully understand the impact of the stormwater management facility on the water quantity and quality within this tributary of Stroubles Creek, monitoring efforts should continue after the wet pond embankment is repaired and is fully operational. If biotic community improvement is desired, the stabilization period could be defined by the time necessary to flush out accumulated sediment within the channel. Monitoring efforts should also expand to include the investigation of the groundwater regime and water level fluctuations within the wet pond. Further measurements of pollutant removal processes and influences upon those processes within the wet pond should also be considered. Last, the influence of the stormwater management facility on downstream flow regimes should be investigated to assess the adequacy of its performance with regard to flow control and prevention of stream channel degradation. / Master of Science

ABSTRACT PHYSIO-CHEMICAL EVALUATION AND FUNCTIONAL ASSESSMENT OF NATIVE WETLAND SOILS AND ORGANIC AMENDMENTS FOR FRESHWATER MITIGATION WETLANDS MAY 2007 EMILY K.D. STOCKMAN, B.S., UNIVERSITY OF MASSACHUSETTS AMHERST M.S., UNIVERSITY OF MASSACHUSETTS AMHERST Directed by: Dr. Peter Veneman Due to the history of wetland loss within the United States a National “No Net Loss” policy was adopted in 1988. This policy requires the creation of mitigation wetlands to replace lost and/or damaged natural wetlands. The role of soil in natural wetland systems is key in providing a number of ecology functions, such as the supply of wetland plant nutrients and the retention of nonpoint source pollutants. Nonetheless, Federal and Massachusetts guidelines regarding the creation of soil and the utilization of organic amendments in mitigation wetlands lack specific parameters and thresholds. This research compares the chemical and physical properties of two commercially available composts and two natural wetland soils and evaluates these materials as possible pollutant sources and sinks. The results of the characterization study demonstrate significant differences between the compost samples and the wetland soils in regards to the following properties: organic matter content, pH, polarity, total nutrients (P, K, B, Zn, Fe, Al, Cd, Ni, Cr) and extractable nutrients (P, K, Ca, B, Mn). These physio-chemical properties influence the functions of supplying plant nutrients and retaining nonpoint source pollutants such as excessive nutrients and herbicides. The results of the nutrient release studies indicate that the compost samples behave as potential sources of excessive levels of phosphorus and nitrate. In addition, the pollutant retention studies concluded that the compost samples sorbed lower amounts of phosphorus under aerobic conditions and lower amounts of the commonly-used herbicide, 2,4-D, as compared to the wetland soils. Overall, the differences in both physio-chemical properties and the behavior of the composts as compared with the wetlands soils as well as each other, substantiate the necessity to re-evaluate Federal and Massachusetts guidelines pertaining to mitigation wetland soil and amendments. Based on the results of this study the following minimal analyses are recommended: organic matter content, pH, total nutrients and extractable nutrients. In addition, based on the phosphorus release and retention studies the following thresholds are recommended to prohibit the release of excessive levels of phosphorus into the mitigation wetland and adjacent aquatic systems: Morgan’s extractable P content ≤ 25 mg kg-1 and/or the total P content ≤ 1286 mg kg-1.

Authorities of municipal separate storm sewer systems (MS4s) are required to address illicit discharges as part of the National Pollutant Discharge Elimination System (NPDES) stormwater program. Field reconnaissance is an effective measure to detect and identify illicit discharges, but requires substantial staff and financial resources to conduct. While risk analysis techniques and guidelines have been developed to facilitate MS4 prioritization of field operations, neither a standard set of indicators nor a standard operating procedure has been adopted. This study investigates the relationships among indicators of illicit discharge potential (IDP) and the locations of illicit discharges in two Virginia MS4s. Results of the study indicate that certain risk factors are statistically more effective at predicting IDP, suggesting that a core set of factors can be used to map illicit discharge risk. The results also show that risk mapping tools are significantly impacted by uncertainty in model inputs. Recommendations are provided for MS4s interested in pursuing IDP risk mapping as a tool to improve cost-effectiveness and guide illicit discharge program implementation. / Master of Science