Sanchez-Trigueros, Fernando; Seay, Laura (The University of Arizona., 2021-08)
      Horse racing in the United States has been around since 1665, but seriously took off after the Civil War in 1868. The sport has always been dangerous, with most of those dangers being manmade. One of the most widely discussed aspects is administering drugs to the racehorses. While drugs may play a part in the number of injuries sustained by the horses, the questions being asked in this project focus on the natural environment surrounding the racing rather than the artificial environment created by man. Does geographic location and climate play a role in horse track fatalities? Data, including number of races per month and fatalities per year, was collected along with specific climate data for each racetrack location from Jan 2009 through December 2020. The data was analyzed using regression testing. Racetrack locations on the west coast were compared to their east coast counterparts. Northern tracks were compared to southern tracks. Through all comparisons, there does not appear to be a strong connection between the geographic locations of the racetracks and the fatalities reported each year. More detailed analysis to determine that correlation is needed.
    • Evaluating replanting priority using GIS: Proposed model for replanting California in the wake of wildfires

      Lukinbeal, Chris; Wade, Alexander (The University of Arizona., 2022)
      As the number and scale of wildfires in California continue to increase, so too has the amount of land in need of replanting. Severely burned areas run the risk of soil loss as unsupported soil formations are eroded by exposure to wind and water, damaging the environment and potentially endangering infrastructure. In order to reduce environmental degradation and potential secondary fire-related damage to infrastructure, a new geospatial model should be developed to help prioritize the most at risk areas for urgent replanting efforts. At the same time, due to the many stakeholders involved with these replanting efforts, such tools should be as easy and accessible for use. This Master’s Project aims to create an automated model that anybody with access to ArcGIS can use. Using publicly available data, the model produces a polygon file of the most at-risk areas in a given burn area on the basis of slope, erosion potential, burn severity, as well as recommended Forest Service species for replanting. Using the instructions provided with the model, the user will be able to locate the raw data necessary to generate a prioritized area file for their own fire incident and customize the model to suit their specific incident. While not a comprehensive tool, this model will provide a starting point for targeted post-fire replanting efforts. For anybody interested in the final model, downloads of the toolbox containing the model as well as a Python script version are available here: https://drive.google.com/drive/folders/1aTjOOsV-ILaLo0eGrZyRNqyWXNWyjkGU?usp=sharing
    • Exploring 3D Visualization Techniques Using Geographic Information Systems Technology at the University of Arizona

      Lukinbeal, Chris; Wadsworth, James (The University of Arizona., 2019-12-11)
      As computers and geographic information systems (GIS) technology improves, more advanced visualization and analysis becomes possible. One area of GIS technology that is seeing improvement is the development of 3D GIS data. The primary focus of this project was to explore three types of building models that can be created from varying quality data and used by a wide variety of users. Using ESRI software, the goal was to provide guidance for GIS users to develop high quality 3D data relevant to their specific needs. Examples of created 3D products are photorealistic-textured buildings, thematically symbolized buildings, and 3D renderings designed for interior navigation. The resulting data were compiled into an interactive web application for visualization and making comparisons between methodologies. All methods involved using 2D building footprint source data and leveraging the attributes and geometry to create 3D structures. These models provide viewers with additional information that would be impossible to convey in two dimensions, such as viewing a route that occupies the same space on different floors of a building, like navigating between offices or classrooms. Interior navigation is one of many examples of an application that can be built upon the fundamental 3D data examined in this project. Additionally, institutions or organizations seeking to develop their first 3D data from 2D data could potentially use the findings of this project to inform their decisions and start supporting the advancement of 3D GIS at a faster rate than if they were to attempt to develop these data independently.
    • Feature Film Residential Use and Aspirational Depictions of People within Los Angeles, California

      Lukinbeal, Chris; Grantham, Laura (The University of Arizona., 2019)
      Feature films and other visual media are well known for not showing realistic portrayals of how people live but rather for depicting an aspirational reality in which the way people are portrayed to live does not match with their social-economic circumstances. This project seeks to probe this phenomenon by examining residential locations used for feature film productions between 2008 and 2011 in Los Angeles County. This project uses GIS analyses and Business Analyst to answer the following question: What residential locations are most prominently depicted in the Greater Los Angeles region in feature films in 2008-2011? More specifically I focus in on which neighborhoods, and homes in those neighborhoods, are used most frequently for feature film production. The project examines the socio-demographic characteristics of the neighborhoods and homes most frequently used in the greater LA area to find what could be called a Hollywood aspirational view of Los Angeles: what it is, where is it located, and what are the predominate socio-demographic makeup of those regions predominantly portrayed.
    • Finding The Tongva

      Korgaonkar, Yoga; Gonzales, Alexander (The University of Arizona., 2022-05-01)
      Finding The Tongva is focused on Locating sites of Tongva influence throughout the county of Los Angeles. The county area was once the homeland of the Tongva Tribe who once had approximately 100 villages throughout Southern California. The Tongva tribe is not well known because the tribe does not have any reservations and most of the land is covered by urban and suburban construction. This project is focused on finding sites of significant Tongva influence to share with the public. The first part of the project was to find various websites that can provide locations and addresses to be converted into point features. These point features are separated into feature layers based on their attributes: Museums, People, Arts, and Monuments. The results show that there are around 100 places of Tongva sites including arts, monuments, museums, and organizations that are dedicated to preserving Tongva culture. The map also includes polygon features such as county boundaries and survey areas to show scale and general area. These results are then uploaded to ArcGIS Online to create a Web Application. This Web Application allows the public to visualize the data and allows for easy user interaction. The widgets allow the public to locate, modify, print, and search for routes on the map. The goal of this project is to preserve the Tongva’s history and to teach the public about the tribe’s value as a culture.
    • Flood Risk Assessment of the Greater St George, Utah Area Based on Land Cover/Land Use and Watersheds

      Sánchez-Trigueros, Fernando; Moertle-Litson, Jasmine (The University of Arizona., 2021-08)
      The Greater St George area in Southern Utah is a hot spot for development. The gradual increase in population size has caused a large growth in construction. In 2018, a large storm hit the area and caused massive flooding in Washington, Utah. This was caused by new construction blocking a natural floodplain. This caused a diversion of the waters into the people’s homes below. The point of this project is to identify the changes in the land from the year of 2008 to 2018 along with displaying the natural water passages in the area. The areas that are overlapped with the flood zones that have been developed on, are at a potential risk of dealing with major flood damage. Using the unsupervised and supervised classification systems on ArcMap along with a watershed analysis, the flood hazard zones information will be displayed within the area. The unsupervised and supervised data signifies that the major flood zones are now encountering more developed areas. This indicates that if more work isn’t done to prevent flooding, then more homes are susceptible to damage. Census data also indicates the communities with the most flooding risk are the low income and high minority communities. The impact of developing the area to support the growing population is ultimately having to cost the city and the citizens more money. The developers need to make sure they examine the natural water ways and avoid causing more flood damage to the city.
    • The Florida Panther: Challenges to Keep This Endangered Species Moving Forward

      Korgaonkar, Yoga; Munoz, Milton (The University of Arizona., 2021-12-13)
      The endangered Florida panther (puma concolor coryi) continues to face challenges for expansion in the southern part of Florida. For decades, the Florida panther existence has been threatened by several factors such as genetic neurological conditions, and habitat displacement. With the rapidly growing population of Southwest Florida, the biggest danger for survival for the Florida panther today is habitat loss, and the proximity to busy roads and highways. The goal of this project is to display current Florida panther geographical range, areas with high indexes of vehicular mortality, and areas suitable for potential growth. Several datasets were obtained and manipulated to produce maps showing panther radio-collared telemetry readings, mortality records, and Florida land use over the years. A similar assessment was done to the Florida black bear, a species facing similar habitat issues in the Southwest Florida region. A habitat suitability model was done to measure potential areas for recovery after decades of extinction danger. Habitat suitability models are essential in the planning and development of wildlife corridors. The findings of this study could be used for Florida panther conservation projects, and wildlife protecting plans to maintain areas suitable for wildlife proliferation.
    • Forecasting Buffelgrass (Cenchrus ciliaris) Distributions In Southern Arizona Under Multiple Climate Change Scenarios

      Sanchez-Trigueros, Fernando; Hellmann, Patrick (The University of Arizona., 2022)
      Buffelgrass (Cenchrus ciliaris) is an invasive grass that can alter fire regimes, reduce local biodiversity, and convert complex arid ecosystems into buffelgrass dominated grasslands. As buffelgrass populations continue to grow, it will be important to be able to predict which areas are most susceptible to future buffelgrass invasion. This study attempts to provide some insight into this problem by creating a model to predict changes in the extent of potential buffelgrass habitat under different climate change scenarios between 2020 and 2100. Maximum entropy modelling was conducted using known occurrences of buffelgrass in the Santa Catalina mountains of Southern Arizona in combination with 19 bioclimatic variables from WorldClim to create a baseline model, which was then applied to future climatic conditions under the Canadian Earth Systems Model 5 (CanESM5) for three different climate change scenarios. The maximum entropy method produced an accurate model with an area under curve (AUC) value of 0.9913 and in validation trails it was able to accurately predict the presence of buffelgrass with 91.37% accuracy. When applied to future climatic conditions, the model showed a 280% increase in potential buffelgrass habitat under light and moderate climate change scenarios, and a 501% increase under a more severe scenario. Considering this potential for buffelgrass to spread, it may be essential for land managers to aggressively combat buffelgrass introductions to prevent it from being able to spread further and continue to damage ecosystems, as well as emphasize the importance of minimizing the impacts of climate change.
    • Geologic Map of Arizona

      Korgaonkar, Yoga; Camp, Michael (The University of Arizona., 2022-04)
      The mission of the Arizona Geological Survey is to provide geologic information to enhance public understanding of the state's geologic character, geologic hazards and limitations, and mineral resources. The maps published by the Arizona Geologic Survey are used by the public and state authorities to assess natural hazards, evaluate construction suitability, and discover mineral and energy resources. The Arizona Geological Survey has been providing geology maps for more than one-hundred years, with its first state-wide geologic map of Arizona published in 1924. The Arizona Geological Survey provides an interactive geologic map of Arizona online, but the website has not been updated in over eight years. The goal of this project is to update the data and software behind the geologic map of Arizona using modern software and software development practices. The final product uses open-source software including Leaflet.js and can be used as a reference for creating future online maps.
    • Geospatial Web-Mapping and Application Development for the Southeast Arizona Sustainable Recreation Strategy

      Little, Jessica (The University of Arizona., 2016-12-14)
      Within the last decade, the United States Forest Service (USFS) has initiated a nation-wide project of Sustainable Recreation as a response to the decreasing amount of resources available to maintain the current recreation infrastructure, including trails, campgrounds, etc. These unmaintained trails and facilities pose a potential safety threat to users and the landscape in which they reside. This smaller pilot project, as part of the Southeast Arizona Sustainable Recreation Strategy, is the second pilot project in the Southwest Region of the USFS aimed at growing the Sustainable Recreation initiative. The main goal of this project is to create the framework for an inter-agency web application of recreation opportunities in Southeast Arizona, with an aim to increase communication between land management agencies, and to increase public participation and conservation of public lands. To achieve this, recreation data were gathered from multiple participating agencies and merged into a new schema in order to provide useful attribute information. This schema was then uploaded to ArcGIS Online and saved as a web map for internal, agency use. In addition, a public-facing web application and corresponding Story Map were also created. The result better portrays the Sustainable Recreation initiative and provides a one-stop-shop of useful recreation information and links for users who wish to become more involved. This project provides the groundwork for which more data from additional agencies and areas can be added and the participation of both land management agencies and the general public can grow.
    • GIS Analysis of the Bighorn Fire Evacuation Orders

      Korgaonkar, Yoga; Camp, Katrina (The University of Arizona., 2022-05-03)
      The Bighorn Fire of 2020 burned 119,978 acres of the Santa Catalina Mountains and threatened urban interface five days into a forty-nine-day burn. Arizona’s Ready, Set, Go! emergency response evacuation plan was activated to ensure the safety of those residing within the danger zone of the wildfire. Evacuation zones were created specifically for this natural disaster which proved confusing for many residents attempting to determine their location in conjunction with the wildfire. This historical spatial analysis depicts the evacuation orders as they were initiated by the Pima County Office of Emergency Management. For each of the twenty-five Pima County evacuation orders initiated during the Bighorn Fire, ArcGIS Pro was used to map each zone by evacuation order and the correlating evacuation status (Ready, Set, Go!). The evacuation meeting point, as well as the animal sheltering location, have been digitized on each map displaying the distance between the evacuation zones and the meeting points. An ArcGIS StoryMap has been created to narrate the events of the Bighorn Fire. An interactive evacuation map was developed using ArcGIS Web App Builder. Users can enter their address and choose a point on the map to determine the distance, route, and length of time from their house to a safe point outside of the evacuation zones. This project will improve understanding of the events that occurred during this natural disaster and the emergency responses used to ensure the safety of citizens near the urban interface. Additionally, it can be used as a learning tool to improve wildfire evacuation communication with the community as well as community safety education.
    • Habitat Suitability Analysis for the Jaguar in the Amazon Biome of Brazil

      Lukinbeal, Chris; James, Riley (The University of Arizona., 2022)
      Jaguars are a keystone species of the Amazon Rainforest and they are suffering from habitat loss at an increasing rate. Brazil remains an integral portion of the jaguar’s habitat, specifically the Amazon Rainforest. This study performs suitability analysis on habitat within the Amazon biome to highlight suitable locations for potential future conservation units. Five variables were used for the analysis, high tree cover, wetlands, shrubs, human activity and terrain ruggedness. A weighted linear combination method was used to compare each variable and produce a map of suitable locations ranked from high suitable (1) to not suitable (4). A majority of the study area was considered high suitable at 80.02%,19.92% was medium suitable, .06% was low suitable and 0% was not suitable. The habitat suitability model was also compared to protected areas within the Amazon biome. When compared to protected areas within the biome, 73.61% of areas fell under high suitable, 26.36% were medium suitable and .04% were low suitable. The areas that fell outside of protected land were 86.52 % high suitable, 13.39% medium suitable and .09% low suitable. These results can lend conservationists, policy makers or other interested parties the groundwork on where to increase protection efforts and ensure the jaguar doesn’t suffer more habitat loss and fragmentation.
    • A Habitat Suitability Analysis of Texas Horned Lizards in Texas and New Mexico

      Sanchez Trigueros, Fernando; Piehler, Reid (The University of Arizona., 2021-05)
      The Texas Horned Lizard (Phrynosoma cornutum) is a state-protected lizard native to the American Southwest. To rebuild the Texas Horned Lizard population, they are bred in captivity and released into the wild. Identifying factors that impact habitat suitability is vital to finding the proper areas for release and reintroduction. Environmental and human factors were examined in Texas and New Mexico counties native to the Texas Horned Lizard, as well as counties without known sightings, to determine which factors most impact habitat suitability. Four statistical and geospatial software packages were used to map, analyze, and evaluate 24 potential variables and it was discovered that elevation, road density, natural gas pipeline density, seasonal rainfall, land use category, and proximity to Red Harvester Ants are all statistically significant to Texas Horned Lizard habitat suitability at a 95% confidence level. Texas Horned Lizards are most prevalent in counties with low elevation, high percentage of open water or snow, low precipitation levels, and native habitats for Red Harvester Ants. Horned Lizards are also less prevalent where road density or natural gas pipeline density is high. No significant difference was detected in habitat suitability relative to Imported Fire Ants as suggested in previous studies. To protect viable environments for Texas Horned Lizard reintroduction, pipeline and road construction should be limited in the most suitable regions: eastern and southern New Mexico, the southern Gulf Coast, the Texas Panhandle, Edwards Plateau, and along the Rio Grande.
    • High Speed / Commuter Rail Suitability Analysis For Central And Southern Arizona

      Deveney, Matthew R. (The University of Arizona., 2015)
      Current transportation methods within the Central Arizona region revolve primarily around automobiles. In order for the region to become more economically resilient and environmentally sustainable, alternative transportation methods must be considered. One such alternative that has shown great promise in other regions of the United States is rail transport. Rail transport, including commuter rail or high speed rail, has proven to not only be an effective alternative to automobile transport, but also as a more environmentally sustainable transportation option. The I-11 Super Corridor study, a part of the University of Arizona’s Sustainable City Project 2014, applied next generation urban planning design ideas to the planned Interstate 11 corridor, a major transportation artery that will connect Mexico and Canada. This study inspired this project’s focus on the concept of identifying suitable routes for new transportation infrastructure within the central and southern Arizona regions. Through the incorporation of commuter or high speed rail within central and southern Arizona, a more resilient regional economy and environment can be created. The previous I-11 Super Corridor study presented the incorporation of different regional factors, including population density and economic statistics, to determine suitable routes for future transportation corridors. This project integrates the utilization of specific local and regional data and advanced GIS analysis to determine suitable routes for new rail transport corridors within Maricopa, Pinal and Pima Counties.

      Lukinbeal, Chris; Stanley, Gregory (The University of Arizona., 2022)
      Harmful Algal Blooms (HABs) are a natural phenomenon occurring 10-50 miles offshore, the size and concentration growing once they become more coastal. These blooms carry a neurotoxin that are not only harmful to marine life, but humans too, creating respiratory problems that could lead to death. Natural conditions such as the amount of sunlight, salinity, and temperature influence their survival and growth but there is also a human factor that accounts to their toxic state. Nutrient rich coastal runoff can attribute to the size and length of time of a red tide; this includes industrial and municipal waste discharge which contains nitrogen and phosphorus, key nutrients that the algae need to grow. This study focuses on an exploration of variables that may or may not affect the size and concentration of the HAB, Karenia brevis, which is responsible for red tides in the Gulf of Mexico, particularly in Florida. I used point data sets for the years 2015-2020 to create density maps that included salinity levels, chlorophyll concentrations, and three Toxic Release Inventory categories to see which affects HABs using Exploratory Regression. Additionally, a hot and cold spot analysis on these six datasets were tested to see if there was any high probability of occurrence around Florida. After running the regression tool, no passing models indicated any variables are related to HABs. However, the criteria VIF and Koenker (BP) of each model did pass as well as hot spots to occur in the Tampa Bay area and Cape Coral.
    • Housing & Race By Location Affordability in Washington State

      Lukinbeal, Chris; Stultz, Sierra (The University of Arizona., 2022)
      This Master’s Report focuses on how price-to-income ratio and race by location affordability affects housing in Washington State. Three types of analyses were used throughout this project. First, a price-to-income ratio using an affordability index was created to show areas of affordable to non-affordable housing. Price-to-income ratio calculates median home value divided by median household income resulting in an affordability ratio. The State of Washington has an affordability ratio of 5.6 and the ten highest ratios were in the following counties: San Juan, Whatcom, Chelan, Jefferson, Whitman, Skamania, King, Skagit, Kittitas, and Douglas. From county to block group level, King County tends to have the highest and most frequent affordability ratio in Washington. Cities and suburban areas tend to have a higher price-to-income ratio compared to the small-town rural areas. Second, race was added to a second affordability index. Race was compared to median home value through dot density and bivariate symbology to visually show race by location affordability. Third, race was compared to median home value and median household income through ordinary least squares linear regression to determine if there is a relationship which was shown. In terms of race by location affordability, majority of Washington State’s White population can afford a house compared to Hispanic/Latino, Black, Asian, American Indian or Alaskan Native, Hawaiian or Other Pacific Islander, and other races able to afford housing. The goal of this project is to bring further insight on where to focus efforts in providing equitable housing opportunities for racial disparities.
    • Identifying Housing Patterns in Pima County, Arizona Using the DEYA Affordability Index and Geospatial Analysis

      Nevarez Martinez, Deyanira (The University of Arizona., 2015)
      When the Fair Housing Act of 1968 was passed 47 years ago, the United States was in the midst of the civil rights movement and fair housing was identified as a pillar of equality. While, progress has been made, there is much work that needs to be done in order to achieve integration. As a country, the United States is a highly segregated country. It is important to understand the factors that contribute to this and it is important to understand the relationships that exists between them in order to attempt to solve the problem. While the legal barriers to integration have been lifted choices continue to be limited to families of color that lack the resources to live in desirable neighborhoods. The ultimate goal of this study is to examine the relationship between the impact of individual indicators and housing patterns in the greater Tucson/Pima county region. An affordability index, the DEYA index, was created to determine where affordability is at its highest. The index includes different weights for foreclosure, Pima County spending on affordable housing, the existence of Pima County general obligations bond affordable housing projects, land value and inclusion in the community land trust. Once this was determined a regression analysis was used to determine the relationship between affordability and individual factors that may be affecting integration. The indicators used were broken down into 3 categories: the categories were education, housing and neighborhoods and employment and economic health.
    • Identifying Opportunities for Community Solar: A Study of Maricopa and Pinal Counties

      Francis, Karol (The University of Arizona., 2016)
      Photovoltaic (PV) solar electricity generation has the potential to reduce the demand for more traditional fossil and nuclear power generation. Community PV solar installations allow energy users to share the electricity generated by these plants. Optimal siting of community solar installations will allow for maximum electricity generation while avoiding environmental conflicts, as well as, minimizing construction costs. This study identifies opportunities for community solar plants in Maricopa and Pinal Counties, Arizona, of ¼-acre in size. Input parameters fall into economic, physical, and environmental categories. Each of the input parameters were classified from 1 (not suitable) to 9 (highly suitable). Next, the classified rasters in each category were weighed according to importance, and Esri’s Weighted Sum tool was used to generate a combined raster for the category. The three resulting environmental, economic, and physical characteristic rasters were weighed again, and the Weighted Sum tool was used to generate a raster of community solar suitability scores. Next, a mask of locations inappropriate for community-scale solar development was created, including lakes, rivers, streams, and residential rooftops, which are too small to accommodate ¼-acre community solar installations. The masked areas were removed from the suitability raster, and the suitability raster was reclassified using standard deviations to generate a preference map with values ranging from 1 (low preference) to 3 (high preference). The model output reveals 68 percent of the study area is of medium or high preference for community solar installations. Maricopa and Pinal counties provide many opportunities for community solar installations.
    • The Inequitable Distribution of the Urban Heat Island in Dallas County, TX

      Korgaonkar, Yoga; Segovia, Isaias (The University of Arizona., 2021-12-16)
      The Urban Heat Island (UHI) effect is a phenomenon where an urban area has a higher Land Surface Temperature (LST) than surrounding rural areas due to human activities. This phenomenon is caused by the increasing urbanization and the removal of green vegetation. The combination of urbanization and climate change has intensified the UHI within urban areas. Certain urban areas can see slightly higher UHI temperatures than other urban areas due to certain demographic, socioeconomic, and land-use factors. This study sought to see how the UHI effect is being distributed within Dallas County, TX. Dallas County has the 8th largest city in the United States which is the city of Dallas. The City of Dallas was one of the cities within the United States that was redlined by the US government. Redlining was the practice that was used to bar minorities from moving into predominantly white communities and obtaining financial resources. This study used data from the Landsat 8 satellite to determine the UHI within Dallas County and how it is being distributed within certain demographic, socioeconomic, land-use, and historical practices. The assessment was done at the census tract level to determine if tracts with higher UHI had differences in the covariates. Thru the assessment, predominantly White areas, with a high median household income, and have areas graded by the Home Owner Loan Corporation (HOLC) as “Best” or “Still Desirable” had a lower UHI temperature. While areas that are predominantly Black or Hispanic with a high poverty rate, a large percentage of areas covered by impervious surfaces, and have areas graded by HOLC as “Definitely Declining” or “Hazardous” have a higher UHI temperature.
    • An Introduction to Identifying Nonpoint Sources of Water Pollution Using a Modified Land Use Conflict Analysis Identification Strategy (LUCIS) Model, Non-point Source Identification Strategy: NPSIS

      Cziesch, Jarrett (The University of Arizona., 2015)
      This paper examines the Non-Point Source Identification Strategy (NPSIS); a modification of the Land Use Conflict Identification Strategy (LUCIS): NPSIS is a raster model useful for identifying non-point sources of water pollution from three known contributors (agriculture, domestic, and natural background). By using a standard operating procedure, developers are able to create standardized datasets useful for identifying non-point sources of water pollution throughout the contiguous United States. The NPSIS model process requires the use of three “non-point source water pollution” contributors. A contributor is termed as a Non-Point Category (NPC) that contains collective elements (i.e. nutrient applications for agricultural purposes and urban runoff from highly developed areas). Using a survey, water resource professionals familiar with chosen study areas rank each NPC element according to potential impact to water quality. Following the survey, raster datasets that represent each NPC and impact to water quality are created using a lowest to highest (“1-9”) ordinal rank system derived from survey results after which each dataset is normalized using a (“1-3”) ordinal rank. Finally, the normalized NPC datasets are combined into one final model useful for identifying each dominant NPC by rank and location within a specified USGS watershed. In conclusion, the modifications to the LUCIS method yields results beneficial for identifying non-point source loads of water pollution.