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Historically, the primary objective of traditional stormwater best management practices (BMPs) was to attenuate peak runoff discharges from urban areas. There has been growing demand to construct BMPs that improve stormwater runoff quality to reduce pollutant loading into downstream water bodies. A BMP located in Herndon, Virginia was retrofitted in 2009. Previously a dry detention pond, the new BMP design contains permanent wet pools as well as elements of Low Impact Development practices. A performance analysis was conducted on the retrofit to determine if the BMP was removing pollutants from stormwater runoff. Two mass-based methods were utilized for the performance analysis: the Summation of Loads Method and Effluent Probability Method. The Kaplan-Meier method and Robust Regression on ordered statistics (ROS) were used to make it possible to include censored datasets in the analysis. Analysis with the SOL method showed removal of suspended sediment, nitrogen, iron, and copper. Export of dissolved solids, phosphorus, organic carbon, and manganese was observed. The results of the Effluent Probability Method showed statistically significant reductions of sediment, iron, and copper across the entire range of monitored storm event sizes (p-value≤0.05). There was no statistical difference between the influent and effluent loads of nitrogen. Negative performance of dissolved solids, phosphorus, organic carbon, and manganese were observed for the entire range of monitored storm event sizes. The results of both methods indicated that the BMP retrofit is effectively removing sediment but failing to achieve significant nutrient reductions. This may be due to the creation of anoxic conditions from the oxygen demand of the micropool sediments and microbial degradation of vegetation within the BMP. Removal of the sediment bed and harvesting of the vegetation would likely improve the performance of the BMP. / Master of Science

The advent of industrial, fertilizer-intensive agriculture during the 20th century has promoted export of anthropogenic nutrients, spurring degradation of ecosystem biodiversity and water quality. Exported nitrogen and phosphorus are recognized drivers of this deterioration, and require management. In the mid-1990s, denitrifying bioreactors (DNBRs), a subsurface, edge-of-field best management practice (BMP) that intercepts and treats agricultural drainage by supporting nitrate-attenuating denitrification with a saturated, carbon-filled substrate, were developed. Since then, their utility has expanded, and recent studies have unearthed biochar's capability to stimulate simultaneous nitrate (NO3--N) and phosphate (PO43--P) removal in DNBRs. This study investigated biochar's potential as an amendment to the traditional woodchip media by conducting nine, five-day trials on twelve laboratory-scale, horizontal flow-through DNBR columns. Three media types were tested: woodchips (W), 90% woodchips and 10% biochar (B10), and 70% woodchips and 30% biochar (B30). Simulated agricultural drainage with four unique concentration combinations of 16.1 and 4.5 mg L-1 NO3--N and 1.9 and 0.6 mg L-1 PO43--P was delivered at hydraulic retention times (HRTs) of 3, 6, and 12 h. Mean NO3--N removal efficiencies ranged from 16.9%-93.7%, and media type was insignificant at low influent NO3--N concentrations, but B30 was the most effective at high influent NO3--N concentrations. Mean PO43--P removal efficiencies ranged from -122.0%-74.9%, with B10 and B30 significantly worse than W at removing PO43--P. These findings corroborate previous work indicating boosted NO3--N removal with biochar, but contradict studies upholding PO43--P-removing capabilities. / Master of Science / Nitrogen and phosphorus-containing nutrients are applied to agricultural fields for supporting higher crop yields, and once these nutrients are exported they can negatively impact ecosystem biodiversity and water quality. These nutrients therefore require management. Denitrifying bioreactors (DNBRs) are subsurface engineered structures that intercept and treat agricultural drainage by supporting nitrate-removing denitrification with a carbon substrate. Recent studies have unearthed the potential of biochar, which is a type of charcoal typically used for soil amendment, as a substrate for promoting simultaneous removal of nitrogen and phosphorus. This study investigated biochar’s potential as an amendment to the traditional DNBR woodchip media using laboratory-scale DNBRs that were subjected to different hydraulic retention times and influent nutrient concentrations. Results revealed that the biochar did not significantly enhance nitrate removal under low influent nitrate concentrations, but did significantly improve nitrate removal at high influent nitrate concentrations. The biochar-amended treatments were significantly worse than the woodchip treatments at supporting phosphate removal. These findings suggest that biochar may indeed boost nitrate removal, but may not improve phosphate removal.

Riparian Forest Buffer Systems contribute to non-point source pollution control and improve the physical and trophic qualities of streams. There is a limited understanding of the full range of costs incurred when implementing a RFBS. Establishment costs will vary with the site characteristics. The amount of forgone income will vary with the current land-use. RFBS enterprises may yield returns that partially or fully offset forgone income. Section A discusses the physical characteristics and functions of RFBS in the Chesapeake Bay Watershed. Section A argues that RFBS design and site characteristics alter the physical ability of RFBS to produce environmental services. Altering design specifications may come at little environmental loss but might greatly reduce landowner costs. Section B describes a decision support system that can provide landowners and policy makers with financial information on the site specific changes in costs that occur as RFBS designs are altered. Section C utilizes the decision support system software to simulate the common design and site characteristics found within the Chesapeake Bay Watershed of Virginia. Generalizations are drawn concerning reduction efficiencies of a RFBS based on the physical characteristics of the regions. Section D discusses government policies and incentive programs, as well as additional private income opportunities, that may influence the cost and adoption of RFBS. Findings revealed a range of annual per acre cost of adoption between $140.09 rising to a positive return of $124.79, depending on assumptions of site characteristics, land-use, and supplemental financial incentives. / Master of Science

Doctor of Philosophy / Department of Agricultural Economics / Jeffery R. Williams / The two topics addressed in this dissertation are both related to surface water quality. Reservoir sedimentation and water quality trading are examined from economic and environmental perspectives. Each topic and the resulting policy implications are relevant to stakeholders at the local, state, and federal levels. Reservoir sedimentation has been recognized as a major environmental, social, and economic issue in much of the Midwestern US. There is an effort to focus public and private funds to achieve the greatest return on the investment from soil erosion and sediment reduction strategies. How can physiographical and economic relationships within the watershed be quantified in such a way to provide insights into the selection of alternative management strategies? This study focuses on answering that question by integrating a physically-based watershed model with an economic analysis of alternative sedimentation reduction strategies for the case of Tuttle Creek Lake located in northeastern Kansas. Several key finding of this study are that both physiographical and economic factors must be considered for cost-effective conservation to occur. Considering these factors and targeting BMP implementation from 8 to 23 times more cost-effective than random implementation. If targeting cannot be done effectively or if “intangible” costs of BMP implementation are too large, dredging is likely to be more cost-effective. While this research compares the cost-effectiveness of various BMP implementation approaches in Kansas with dredging, the benefits associated with each of these strategies is not addressed. While there is substantial evidence that nonpoint sources have lower nutrient reduction costs than point sources, experience with water quality trading (WQT) reveals a common theme: little or no trading activity. These outcomes suggest the presence of obstacles to trading that were not recognized in the design of existing programs. To examine the ways that various market imperfections may impact the performance of a WQT market, an agent-based model is constructed, which simulates a hypothetical point-nonpoint market. This study first presents an overview of the concepts and simulation modeling technique used and then analyzes the effects of two prominent market impediments identified in the WQT literature: information levels and trading ratios. The results imply that if market designers feel that only a limited number of trades will be consummated, creating an institution that provides accessible information about buyers’ prices is preferred to providing information about sellers’ prices. Overall, more information is always better, but it becomes less important with higher trading ratios.

Few elements in surface waters are monitored as closely as phosphorus (P) due to its role in the eutrophication and degradation of surface waters. Limiting P mobilization from source areas is, therefore, a central goal of water quality protection plans. But the work of locating sources in mixed-use watersheds is challenged by the spatial and temporal variability of critical source areas (CSAs) of P. Synoptic sampling is a proven method for capturing the spatial variation of water quality parameters in surface waters, though it's not often used to track temporal dynamics across the same study area. Phosphorus fractionation is an analytical method that divides the total P (TP) in water into fractions, which for this study included total dissolved P (TDP), particulate P (PP), dissolved reactive P (DRP), and dissolved organic P (DOP). The objective of this study was to demonstrate the utility of combining temporally repeated synoptic sampling with simple P fractionation as a unique strategy for locating and characterizing CSAs of P. Seven synoptic sampling campaigns were conducted over a two-year period (March 2015 – July 2016) in a rural, montane watershed in north central Utah, USA. In each campaign, we sampled 18 sites across three tributaries (Main Creek, Spring Creek, and Little Hobble Creek) during three distinct, annual hydrologic periods (rising flow, peak flow, and baseflow). Temporal repetition clearly identified the rising flow period as the period with greatest P loading in the watershed. Combining repeated synoptic sampling and P fractionation successfully identified CSAs of P and most probable transfer pathways. Specifically, stream segments along lower Spring Creek and Main Creek were associated with the greatest increases of PP loads during periods of rising flow and peak flow. In the same time periods, the greatest DOP loads stemmed from forested areas as well as areas in the lower watershed associated with winter grazing of cattle. The watershed exhibited a significant background concentration of DRP from groundwater-driven subsurface sources in the lower half of the watershed that persisted year-round. These assessments can be used to develop management practices that limit various P loads from these respective critical source areas. The characterization of CSAs could not have been made using only a traditional synoptic sampling approach. This study demonstrated that the combination of repeated synoptic sampling and P fractionation can be an effective technique for locating and characterizing critical P source areas in order to guide best management practices that improve surface water quality.

The introduction of sustainable stormwater management in society has proved complex. Most cities do not operate jointly planned and owned stormwater facilities and institutional barriers have proved difficult to overcome. Experience from a Swedish project where extensive changes were made in the Augustenborg area in Malmö shows that it takes many years to overcome institutional obstacles when a society undergoes transformation.   Major part of research is still based on engineering and technical function although the social perspective is of great importance for the functioning of sustainable stormwater management. In-depth knowledge is needed about sustainable stormwater management and its connection with composition of population and socio-economic conditions. Research needs to be done on how information campaigns and cooperation are best designed to simplify planning, construction, and maintenance of stormwater facilities.

Using benthic macroinvertebrates to measure stream health has been widely used and accepted around the world. Macroinvertebrates are resident monitors of chronic impairment in a stream since they are relatively sessile and most commonly respond to disturbance by drift but can recolonize a restored stream reach very quickly. This study tested the effectiveness of macroinvertebrate metrics developed through the Rapid Bioassessment Protocol (RBP) to detect changes in stream integrity as the result of placement of a best management practice (BMP), installed on a tributary of Roaring Branch, located in Columbus, Georgia. The BMP was designed to attenuate flow to reduce sediment suspension and downstream deposition. A sampling protocol derived from the Georgia Ecoregions Project was implemented to evaluate the macroinvertebrate community, located downstream of the BMP, and downstream of the confluence with Roaring Branch, both before and after the BMP installation. The resulting metrics were compared to a reference condition described for subecoregion 65c, sandhills-lower piedmont. A dramatic improvement or increase of macroinvertebrate populations suggests an improvement in water quality (via reduction in fine sediment deposition) due to improved physical habitat conditions for indicators (Trichoptera) of healthier streams. The results of this study suggests further restoration activities should continue and that re-evaluation of the sampling protocol should take into account a larger subsample size of benthic macroinvertebrates than currently recommended by the RBP.

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