Mountain Scholar :: Browsing by Author "Hoag, Dana, committee member"

Browsing by Author "Hoag, Dana, committee member"

Now showing 1 - 8 of 8

Open Access
A cross sector evaluation comparing nutrient removal strategies in urban water systems
(Colorado State University. Libraries, 2019) Hodgson, Brock, author; Sharvelle, Sybil, advisor; Arabi, Mazdak, committee member; Carlson, Ken, committee member; Hoag, Dana, committee member
Water supply management and reduction of nutrient pollution from urban water systems are two of the most important issues facing utility managers today. To better protect water supplies, many states have or are establishing total nitrogen (TN) and/or total phosphorous (TP) loading restrictions from urban water systems. Traditionally, these targets are met by wastewater treatment facility (WWTF) improvements, but stringent regulations can make this challenging and costly. As regulations increase it may be necessary or more cost effective to consider additional options for nutrient removal from urban water systems including water management practices or stormwater control measures (SCMs). There are a wide range treatment approaches that can be considered at a WWTF for improving nutrient removal but evaluating these scenarios can be challenging and is traditionally accomplished via mechanistic models specific to individual WWTFs requiring process expertise and a rigorous sampling and analysis program. Water management practices are traditionally considered for water supply improvement, however there is little research to characterize the impact on water quality. There is a need for additional research and tools that facilitate estimating effectiveness of various nutrient removal technologies and consider cross sector strategies and tradeoffs between adoption of practices. To understand the impacts of water management practices, the impact of indoor conservation, source separation, and graywater and effluent reuse on WWTF influent and effluent and downstream water quality was characterized identifying which practices can potentially help meet nutrient reduction targets. For WWTF technologies, previously calibrated and validated mechanistic models were used to develop a simplified empirical model to more easily estimate and compare the effectiveness of various WWTF technologies as a function of influent wastewater quality. The findings from the water management practice evaluation and WWTF treatment comparison provided the framework for conducting an urban water systems evaluation by using the developed empirical models combined with the benefit of stormwater control measures (SCMs) characterized via the Simple Method to evaluate a multitude of strategies for meeting nutrient removal targets in the urban water system. Lastly, this research considered the impacts on biosolids management with the increase of liquid stream removal at the WWTF. The research identified source separation and effluent reuse as frequent part of effective nutrient removal strategies and part of an optimal nutrient removal strategy, and even necessary under stringent nutrient requirements. In terms of wastewater treatment, the benefit of adopting more advanced wastewater treatment processes will be most beneficial in carbon limited WWTFs, and negligible when there is adequate carbon for biological nitrogen and phosphorous removal. This includes sophisticated processes like nitrite shunt and 5-Stage Bardenpho and sidestream processes like struvite precipitation and ammonia stripping. While improvements to WWTF are likely with adoption of stringent nutrient regulations a multi objective optimization identified water management practices and SCMs to be part of all non-dominated nutrient removal strategies. As nutrient requirements become more stringent, the options for WWTFs in terms of processes are limited and frequently a combination of water management practices and SCMs is necessary. This was demonstrated via a systems analysis of cost-effective nutrient removal solutions in urban water systems that can be easily applied to other urban systems because of the empirical models developed with this research. These tools are necessary to help utility managers identify optimal nutrient removal strategies. As utilities invest in improvements to WWTF operations, there may also be notable impacts on biosolids management, primarily in terms of phosphorous, which may limit land application rates resulting in additional cost or disposal of biosolids that historically have been beneficially used in agriculture. These impacts must also be considered by utility managers when considering optimal nutrient removal strategies from urban water systems.
Open Access
Assessing nutrient management scenarios at the system level
(Colorado State University. Libraries, 2017) Jobin, Olivia, author; Arabi, Mazdak, advisor; Hoag, Dana, committee member; Sharvelle, Sybil, committee member
The exponential increase in urbanization and population has led to water quality degradation throughout the country. This can be linked to the increase in impervious surfaces from urban expansion, most wastewater treatment plants (WWTPs) not being equipped to handle higher nutrient inflows, and the exponential demand for food that has led to more intensive farming practices that erode and degrade the soil, further enhancing runoff. The overall goal of this study was to assess nutrient management scenarios at the system level. The objectives included: 1) determine a methodology that could be used to quantify nutrient load contributions from each sector at the watershed scale; 2): determining delivery ratios for each sector based on the ambient nutrient loads at the outlet of the watershed; 3): and assess the cost, equity, and water quality effects of conservation management practices, BMPs, wastewater treatment technologies, and water conservation practices. Assessing the effectiveness of agricultural management practices is often jeopardized by lack of comprehensive monitoring data and computational burden at larger scales. The Soil and Water Assessment Tool (SWAT) within the eRAMS platform was used to assess the benefits of different agricultural management practices at field and watershed scale for the South Platte River Basin (SPRB), a moderately large semi-arid watershed located in northeastern Colorado. The model was calibrated using measured field observations from a study site in the watershed where the target management practices were implemented and monitored for their effectiveness. The agricultural management practices studied included fertilizer application rate and timing, tillage practices (i.e. conventional, reduced, strip, and no-tillage), and center pivot versus surface irrigation for roughly 21,000 irrigated agricultural fields (740,000 acres) in the SPRB. Center pivot irrigation showed the highest potential for nutrient reduction while tillage practices had an intermediate effect. Due to interim warm water instream total nitrogen (TN) and total phosphorus (TP) levels being exceeded over the period of 2002-2015, nutrient management scenarios were assessed at the system level for the Cache la Poudre (CLP) watershed in Colorado. The CLP watershed consists of 13 WWTPs, as well as irrigated agricultural fields, forested land, rangeland and urban areas making it an ideal candidate for this analysis. The scenarios created involved a combination of different practices and technologies for each sector and their associated costs to determine cost effective solutions for the issue at hand. A Gini Index coefficient was also determined in order to determine how equitable each scenario was. Models were used to determine the nutrient load contributions over the 14 year time frame with and without the implementation of the different practices and technologies tested, and were validated based on previous research and monitoring data. It was found that TN reductions needed for regulations could be achieved through the adoption of carbon addition, WWTP effluent reuse, 10% adoption of strip tillage, and a 25% adoption of bio-retention basins for a total of roughly $6,000,000. Whereas the TP reduction needed for regulations for all hydrologic conditions could not be achieved with any combination of the practices looked into, however 2 out of the 3 reductions could be achieved from the adoption of Chem-P, WWTP effluent reuse, 10% adoption of strip tillage, and 25% adoption of bio-retention basins for roughly $11,000,000. Further research would be needed to determine a scenario that could achieve a 70% TP reduction and 40% TN reduction simultaneously at the outlet, which was needed at the system level to be in compliance with regulatory standards.
Open Access
Confronting the natural variability and modeling uncertainty of nonpoint source pollution in water quality management
(Colorado State University. Libraries, 2017) Tasdighi, Ali, author; Arabi, Mazdak, advisor; Bledsoe, Brian, committee member; Bailey, Ryan, committee member; Hoag, Dana, committee member
Nonpoint source pollution is the primary cause of impaired water bodies in the United States and around the world. Hence, managing the water quality is hinged mainly on controlling this type of pollution. However, characterization of nonpoint source pollution is extremely difficult due to high inherent natural variability and uncertainty. Nonpoint source pollution loads depend on climate, land use, and other environmental conditions that are highly variable by nature. On the other hand, since it is often infeasible to measure pollutant loads from nonpoint sources within a watershed using monitoring campaigns, models are increasingly used to estimate these loads. Models are simplified representations of reality. Consequently, they are subject to various sources of uncertainty including: model parameters, input data (climate, land use, etc.), model structure (conceptualization), and measurement data (streamflow, nutrient concentrations or loads, etc.).
Open Access
Distribution and economic analysis of Prosopis juliflora in Ethiopia
(Colorado State University. Libraries, 2015) Wakie, Tewodros T., author; Laituri, Melinda, advisor; Evangelista, Paul, advisor; Hoag, Dana, committee member; Jarnevich, Catherine, committee member
Invasive species are one of the drivers of biological and socio-economic changes around the world. Over the past 30-40 years, the non-native Prosopis juliflora plant has emerged as a major invader of the arid and semi-arid regions of Ethiopia. Information on its distribution, impact, use and management is highly needed to contain and prevent the spread of this highly invasive plant. In the first study, I used a correlative modeling framework to track and map the current and potential distribution of P. juliflora in Afar, north-eastern Ethiopia. Specifically, I used time-series of Moderate Resolution Imaging Specrtoradiometer (MODIS) satellite imagery, 143 species-occurrence records and the Maxent modeling technique to map its current distribution. I then used topo-climatic predictors, species-occurrence records and the Maxent software to map its forecasted distribution. I found that the current extent of P. juliflora invasion in the Afar region is approximately 3,605 Km2, while its predicted distribution is approximately 5,024 Km2. My findings demonstrates that MODIS vegetation indices and species-occurrence points can be used with Maxent modeling software to map the current distribution of P. juliflora, while topo-climatic variables are good predictors of its potential habitat in Ethiopia. In the second study, I used a participatory research framework to map P. juliflora over a fine geographic scale, and to identify the major resource related problems in the region. I learned about the introduction history, spread, impacts, uses and traditional management practices of P. juliflora in Afar by interviewing 108 pastoralists and agro-pastoralists. Additionally, I detected the land-cover categories most affected by P. juliflora invasion by superimposing community produced maps on ancillary land-cover layers, and performing overlay analysis. Prosopis juliflora has highly invaded grasslands and open areas in Afar. The species displaces useful native grass and forage species, which are important for sustaining the region's wildlife and livestock resources. In addition to threats from invasive species, Afar people face conflicts from neighboring Issa ethnic groups, and land-grabs from the central government and foreign investors. The findings demonstrates that participatory mapping methods are suitable for mapping species distribution, detecting land-cover changes, and managing invasive plants. High invasive species control costs have swayed most developing countries to adopt cost effective P. juliflora eradication and utilization practices. However, the effectiveness and economic viability of these new approaches have not been thoroughly tested. In the third study, I used an economic analysis framework to assess the economic feasibility of selected P. juliflora eradication and utilization methods that are practiced in southern Afar. The dominant P. juliflora eradication option was to convert infested lands into irrigated farms, while the preferred utilization options were to make animal fodder from P. juliflora seed pods, and to produce charcoal from P. juliflora wood. I interviewed 19 enterprise owners (i.e., farmers, flour producers and charcoal makers) and collected primary data on prices, yields, costs and revenues. I assessed the economic feasibility of the selected methods by performing enterprise, profitability, sensitivity and risk analyses over 10 years and an interest rate of 10% per year. Converting P. juliflora infested lands into irrigated agriculture is a profitable and risky P. juliflora eradication approach. Charcoal making is a moderately profitable and less risky utilization approach, while flour production is a risky and an un-profitable utilization approach. Introducing new changes in the production and management steps of flour production may be needed to make flour enterprises profitable. My overall economic analysis suggests that control through utilization may be one of the effective and economically viable P. juliflora management strategies currently accessible to Ethiopia. I generated reliable information on the distribution and impacts of P. juliflora in Afar by employing a wide variety of scientific approaches. My results can guide local level P. juliflora utilization and control efforts in Afar, while my methodologies can be replicated for managing invasive plants in other developing countries.
Open Access
Exploring compensation programs and depredation reporting for wolf-livestock conflict across the North American West
(Colorado State University. Libraries, 2021) Nickerson, Rae, author; Evangelista, Paul, advisor; Breck, Stewart, advisor; Niemiec, Rebecca, committee member; Hoag, Dana, committee member
With the continuing reestablishment of wolves (Canis lupus) across the American West, livestock producers will be increasingly exposed to wolf-related conflict such as livestock depredation. The financial implications of wolf conflict can be significant depending on the context of an individual livestock operation. Compensation programs administered by government agencies and occasionally non-government organizations aim to ameliorate some of the financial risks associated with wolves and the loss of livestock; yet the effectiveness of these programs at fostering tolerance and adequately addressing losses is increasingly questioned. Reporting depredation is often required for compensation eligibility, and reports are the primary source of data used by wildlife agencies to address conflict and inform local management. Yet not all producers report depredation or utilize compensation, and we know very little about what factors motivate reporting and compensation use. Additionally, we know very little about producer perspectives on existing compensation programs or whether producers are interested in alternatives. I designed an exploratory survey based on an expanded version of the Theory of Planned Behavior to identify the social-psychological and demographic factors most strongly correlated with compensation use and wolf depredation reporting intentional outcomes. I also utilized a simplified Discrete Choice Question to gauge producer interest in alternatives to traditional compensation programs. My online survey was sent to livestock producers across Arizona, California, Colorado, Idaho, Montana, New Mexico, Washington, Wyoming, and Alberta, Canada (n=165 responses). While 87% of respondents experiencing wolf depredation had reported a depredation in the past, only 69% had utilized compensation. Levels of satisfaction with existing compensation programs were mixed. The most common reasons stated for not applying for compensation included dissatisfaction with the depredation confirmation process (too much validation and/or paperwork), that the amount of compensation available is not enough or not worth the hassle of applying for compensation, and a lack of trust and satisfaction with state government employees and their wolf management decisions. Using Lasso regression, I found that descriptive norms (p<0.01), age (p<0.01), and past experience with depredation (p<0.05) were the strongest predictors of reporting intention. Trust (p<0.001), perceived risk (p<0.05), descriptive and personal norms (p≦0.05), attitudes (p<0.05), and state of residence (varied by state) had the strongest relationship with compensation use intention. The overall predictive power of my models was high, suggesting the expanded Theory of Planned Behavior model was effective at predicting both behavioral intentions. The results of my Choice Question suggest that my surveyed population wants access to diverse and adaptive payment and engagement options for wolf depredation. I also found that although these producers are interested in alternatives like Habitat Leases and Cost-Shares for financial and technical assistance with conflict reduction tools, they still want access to traditional compensation for depredation to address local variation in depredation across neighboring operations. Although limited by my sample size, these findings suggest that 1. building interpersonal trust between wildlife agency personnel and livestock producers, 2. reducing wolf-related financial vulnerability by providing compensation for indirect losses and/or undetected wolf depredations in addition to payments for depredation, and 3. building descriptive norms by providing peer-to-peer knowledge sharing opportunities for producers to share with one another may all increase reporting and compensation use intentions among livestock producers, and by extension, may influence behavior.
Open Access
Geospatial decision support system for ameliorating adverse impacts of irrigated agriculture on aquatic ecosystems
(Colorado State University. Libraries, 2019) Fields, Christopher Michael, author; Labadie, John, advisor; Johnson, Lynn, advisor; Gates, Timothy, committee member; Hoag, Dana, committee member
Although irrigation is key to the success of agriculture in much of the western United States, the associated water resource demands are often at odds with the needs of aquatic ecosystems. The storage and redistribution of natural water supplies that is required to meet agricultural demands often disturbs the natural streamflow regime that is key to the stream ecosystem. In many cases the conflicts between agricultural and ecological demands have led to increased regulatory restrictions on agricultural diversions to protect instream flows. While the results of such policies can help mitigate the most severe impacts of stream diversions, these regulations often result in agricultural shortfalls while achieving suboptimal environmental benefits. The Russian River basin in northern coastal California is a prime example of a region that is facing the challenges created by the often-disparate needs of agricultural and environmental interests. As the primary agricultural activity in the basin, wine grape cultivation is the largest water user in the basin with spring frost protection and summer irrigation constituting the bulk of those demands. At the same time, the Russian River and its tributary system have been identified by the U.S. Fish & Wildlife Service as critical habitat for the endangered coho salmon and the threatened Chinook salmon and steelhead trout, which rely on the highly stochastic and seasonal natural streamflow patterns of the system to support their life cycles. To reduce disruption of the natural streamflow regime and protect instream flows in the critical habitat, the California State Water Resources Control Board (SWRCB) has imposed a series of regulations that limit diversions. While a variety of studies in the Russian River basin have focused on the impacts of tributary diversions on instream flows as well as the effects of environmental regulations on streamflows and agricultural security, there is a lack of research that incorporates hydrometeorological modeling into such studies. To address this research gap and further study the effects of agricultural diversions and environmental regulations, a geospatial decision support system (geo-DSS) that combines a gridded hydrometeorological streamflow model (HL-RDHM) with a GIS-based river basin management model (GeoMODSIM) was developed and applied within the Russian River basin. In a proof-of-concept implementation, the geo-DSS is first applied to a representative tributary in the Russian River basin that has been categorized as critical fisheries habitat and supports viticulture. The geo-DSS incorporates unimpaired flow estimates from the fine-scale (1/4 HRAP or approx. 1km) gridded HL-RDHM model with GeoMODSIM, which evaluates water management impacts and uses a one-day timestep. The resulting model implementation is used to evaluate current agricultural water management practices, the effects of environmental regulations, and agricultural water management alternatives in the basin. The geo-DSS was shown to accurately represent the impacts of short-term spring frost protection demands and the continuing impacts through the summer irrigation season on instream flows, which can be detrimental to the threatened and endangered (TES) fish species in the region. Additionally, the implementation of minimum bypass flow environmental protections was shown to severely limit agricultural water supply. Finally, model results indicate that through the use of improved agricultural water management practices, such as off-stream ponds, overall system supplies are adequate to meet agricultural demands while satisfying environmental instream flow restrictions. In a second study, the geo-DSS was applied on a larger scale to the Feliz Creek tributary system in the upper Russian River basin to assess baseline conditions that included appropriated water rights, minimum bypass flow restrictions, existing agricultural pond storage, and agricultural demands. The baseline model framework was run with 100 sets of hydrologic forcing data to assess system performance across a variety of hydrologic conditions that ranged from dry to wet. Baseline results indicate that even with environmental restrictions in place, the cumulative impacts of upstream diversions can still be significant during low flow periods and agricultural supply shortfalls were common throughout the system. In subsequent scenarios agricultural management alternatives were evaluated to improve overall system performance. Results of these scenarios demonstrate that the addition of supplemental agricultural pond storage can significantly reduce agricultural supply shortages while making significant improvements to instream flow conditions. Additionally, the allowance of carryover storage from year to year, which is currently restricted in the basin, was shown to result in even more significant improvements. Finally, the model was used to identify the optimal location and size of supplemental storage within the basin. Overall, this type of tool is key to achieving the environmental instream flow goals in the Russian River basin while maintaining and enhancing the agricultural industry of the region.
Open Access
Three essays on producer response to information disclosure
(Colorado State University. Libraries, 2023) Yu, Shuiqin, author; Costanigro, Marco, advisor; Burkhardt, Jesse, committee member; Hoag, Dana, committee member; Cutler, Harvey, committee member
This dissertation consists of three chapters studying how information and beliefs affect producers' behavior and decision making. The first chapter studies the effect of the Local Inspector Value Entry Specification (LIVES) program on restaurant hygiene in North Carolina. The LIVES Program, a collaboration between Yelp.com and municipalities, enables the display of restaurant inspection reports on Yelp's platform, simplifying access for consumers. Combining individual restaurant inspection data and restaurant level demographic data from Yelp.com, this study employs a difference-in-difference approach and geographic regression discontinuity design to analyze the LIVES program's impact on restaurant hygiene. The difference-in-difference analysis reveals a 1.143-point improvement in inspection scores for treated restaurants. The geographic regression discontinuity method, utilizing a neighboring county as a control group, corroborates the LIVES program's positive influence. The second chapter examines the effect of online consumer reviews on restaurant workers' wages. Online consumer reviews significantly influence the demand for experience goods, including movies, books, and restaurant meals. However, research on the impact of online reviews on restaurant workers' wages remains scarce. Utilizing decade-long panel data of quarterly consumer reviews and restaurant wages, this study demonstrates that an increase in average star ratings causes restaurant workers' wage growth. Notably, the effect varies across chain, major chain, and independent restaurants. The final chapter studies how Colorado farmers' and ranchers' subjective beliefs about the cost of adoption affect their intention to implement conservation practices. Promoting the adoption of conservation practices among farmers is challenging. Despite extensive research into farmers' reluctance to participate in conservation programs, few studies investigated how farmers' personal beliefs on the cost of adopting conservation practices affect their willingness to participate in those programs. This study adds to the literature by surveying over 150 Colorado farmers on their preferences for monetary and technical support regarding conservation tillage, soil testing, filter and buffer strips, and controlled-release fertilizers. Results from a choice experiment indicate that respondents' beliefs about costs can explain a large portion of the variation in farmers' willingness to adopt conservation practices.
Open Access
Waste to resource - beneficial use of water treatment residuals as a stormwater control measure amendment for phosphorus removal
(Colorado State University. Libraries, 2020) Shehab, Omar, author; Grigg, Neil, advisor; Sharvelle, Sybil, committee member; Hoag, Dana, committee member
The increase in nutrient pollution is an alarming issue, and innovative and cost-effective measures need to be taken. This study addressed two issues: removing dissolved phosphorus introduced through stormwater runoff using water treatment residuals (WTRs) and the economic value of diverting this waste material from landfills to be used as an amendment in stormwater best management practices for treating stormwater runoff. The City of Fort Collins has monitored a bioretention rain garden located at a municipal facility for several years and has consistently seen a slight decrease and, at times, even an increase in the total mass of phosphorous in stormwater effluent leaving these facilities. The increase in mass was primarily due to higher dissolved phosphorous concentrations in the rain garden's effluent. Based on prior research at Colorado State University, the use of water treatment residuals (WTRs) was selected for laboratory-scale analysis and field-scale evaluation. This research aimed to evaluate whether this waste material generated during drinking water treatment operations could be diverted from landfills and instead, used as an amendment in stormwater best management practices (BMPs) for treating stormwater runoff. Simultaneously, it is hoped that this waste product's beneficial use can result in a safe and significant reduction in dissolved phosphorous input into water bodies. WTRs from the local water treatment plant were evaluated and found to have a very high adsorptive capacity for phosphorus with a phosphorus sorption capacity (PSC) of 21.56 lbs. dissolved phosphorus per ton WTRs, making it a strong candidate as an amendment to current BMPs. A column test was conducted to demonstrate a proof of concept for how WTRs can reduce phosphorus loads leaving BMPs. Column tests revealed that exposure time and application location (top, mixed, or bottom) of WTRs within the BMP media were the critical factors of phosphorus removal. A study was also conducted to determine how much phosphorus load could be reduced if WTRs were applied to BMPs throughout Fort Collins. The citywide analysis displayed a significant reduction, if not an elimination, of the need to send this current waste product to local landfill facilities, thereby reducing disposal costs and increasing the useful life of local landfill operations. The current operation by the City of Fort Collins disposes WTRs into the county's landfill. This study estimated the cost of current operations, the cost of using WTRs in stormwater BMPs, and an additional potential scenario in where the landfill was moved twice as far. Transportation, tipping/application, and staff time were the main cost components and were estimated for the different scenarios. It was found that using WTRs as an amendment in stormwater BMPs would save the City around $5,000 annually compared to the current operation and $13,000 compared to the disposing of WTRs to the new landfill. The outcome of such an approach was shown to be not only economical, but it also provided environmental and social benefits as it would reduce dissolved phosphorus significantly from stormwater runoff, which results in improved water quality and elimination of a current product.

Browsing by Author "Hoag, Dana, committee member"

Results Per Page

Sort Options