Risk Assessment of Phosphorus Loading in the Lake Champlain Basin Alison Nord, Anna Speed, Ashley Murphy

Transcription

1 1 Risk Assessment of Phosphorus Loading in the Lake Champlain Basin Alison Nord, Anna Speed, Ashley Murphy Executive Summary Phosphorus is one of the most damaging sources of pollution currently affecting Lake Champlain. Phosphorus emanating from different sources is degrading the Lake Champlain basin and its surrounding habitats. Phosphorus loading into the lake is traced to point sources such as wastewater treatment plants and nonpoint sources such as agricultural runoff. Important habitats affected by phosphorus are mainly aquatic; this includes open water, rivers and streams, lakes and ponds, and wetlands. The purpose of this study is to further identify the sources of phosphorus and rationalize each source s effect on overall phosphorus loads into the basin. This study will also analyze the habitats affected by excess phosphorus and propose associated impacts on these habitats. The central goal of this study is to compose a complete, comprehensive report on the state of the lake and create an ecological risk assessment for the Lake Champlain Basin. We will assign a rank to each source and habitat in relation to phosphorus and subsequently obtain the total risk score from assigned ranks for each watershed within the Lake Champlain Basin. Problem Statement The loading of phosphorus into Lake Champlain is a great stress on lake habitats and aquatic species, and advances water quality degradation due to its persistence in lake watersheds. Background Phosphorus is a primary macronutrient essential for plant growth and function. However, in abundance phosphorus can yield damaging results to an ecosystem, and thus is identified as a pollutant. When phosphorus is loaded in excess into the lake, algae prospers, creating algal blooms. Algal blooms result in dissolved oxygen in the water depletion by plant photosynthesis, yielding massive fish kills due to inadequate oxygen levels in the water. These algal blooms also disrupt recreation in the lake as they negatively impact water quality and depending on the type of algae, can release toxins that are hazardous to human and animal health. The Lake Champlain Basin Program (LCBP) has been researching these deleterious effects on the lake ecosystem in order to develop a Total Maximum Daily Load (TMDL) of phosphorus from all sources within the watershed. A TMDL is used by the U.S. Environmental Protection Agency (EPA) to describe a value of the maximum amount of a pollutant that a body of water can receive while still meeting water quality standards. The Lake Champlain Basin Program s most recent phosphorus TMDL proposal to the EPA was denied in January of this year(2011). The LCBP has been conducting research to identify sources of phosphorus in order to apply stricter regulations throughout the basin. Goal/Purpose 1

2 2 The purpose of this study is to determine the general sources of phosphorus and the habitat types affected by it within the Lake Champlain Basin. A ranking system will be created to evaluate the magnitude of effect for each source and habitat, which will be critical in helping create a complete, unified ecological risk assessment of Lake Champlain. Objectives Analyze peer-reviewed literature to gain an understanding of the current impacts of phosphorus on Lake Champlain Identify and analyze all sources contributing to phosphorus Identify pathways between sources and habitats Evaluate the magnitude of effect phosphorus has on each habitat Rank each source of phosphorus Rank each of the habitats phosphorus affects Obtain the total risk score from assigned ranks for each watershed within the Lake Champlain Basin Approach In this study, information regarding phosphorus pollution in Lake Champlain was gathered through review of scientific articles and other scholarly publications. Peerreviewed articles were obtained through the University of Vermont Libraries website using the following search engines: EBSCOhost, Science Direct, the Canadian Journal of Fisheries & Aquatic Sciences, and the Journal of Environmental Quality. Additionally, information was collected from the Vermont Agency of Natural Resources and the Vermont Agency of Agriculture, Food and Markets. Sources of use suggested by instructors and peers, include the Lake Champlain Basin Program website (LCBP.org), the State of the Lake and Ecosystem Indicators Report- 2008, generated by the LCBP, as well as Opportunities for Action. The Lake Champlain Phosphorus TMDL was instrumental in determining the current controls on phosphorus inputs in the basin as well as the areas in which phosphorus loading is still a major concern. The LCBP s Opportunities for Action program was used as a resource to identify what tasks the LCBP has already assigned for controlling phosphorus. The most common key words used in our searches were Phosphorus, Lake Champlain, and LCBP. Each article was carefully reviewed and analyzed, culminating in a literature review briefly explaining the significance of each source. A graduate student in the Plant and Soil Science department, Eulaila Ishee, was consulted to further gather information regarding sources of and habitats affected by phosphorus. Eulaila is working on a study that is measuring phosphorus concentrations in soil along eroded stream banks in Chittenden County, and thus has ample knowledge concerning phosphorus within the basin. Eulaila was able to provide insight into the rankings assigned for sources of phosphorus and habitats impacted by excess phosphorus. She also identified several key papers that contributed to the findings portion of this 2

3 3 report. Findings Phosphorus aids in rapid plant growth and is naturally occurring in many ecosystems (Brady & Weil, 1996). Phosphorus in plants is used by adenisine triphosphate (ATP), an energy-storing compound. The ability of plants to incorporate phosphorus into their structure helps with the transformation of solar energy into chemical energy, proper plant maturation and their ability to withstand stress. Synthetic and biological fertilizers exploit this process to accelerate plant growth in agricultural and urban settings. Often, the application processes create large amounts of excess fertilizer that cannot be taken up by plants and are therefore washed away in storm water. This excess phosphorus load is carried in runoff from these areas and released into waterways. (Brady & Weil, 1996) Phosphorus does not have a gaseous phase and therefore, travels in sediment and water. In water, phosphorus exists in a particulate phase or a dissolved phase. Phosphorus is most readily available to plants in its orthophosphate phase, which is measured through soluble reactive testing. Particulate phosphorus, while organic, is not as readily available to plants. In this Ecological Risk Assessment (EcoRA), calculations of total phosphorus contributed by identified sources were considered to determine rankings. Total phosphorus is, as the name implies, a measure of all phosphorus, particulate and dissolved, in a sample. This measure is often seen as inaccurate when considering the damaging effects of phosphorus in waterways. Soluble reactive phosphorus is often cited as the relevant test to determine the detrimental phosphorus. However, it can be argued that the transformations between the types of phosphorus would be reason to consider Total phosphorus. Accounting for the total phosphorus will yield a more thorough measure of potentially available phosphorus. Particulate phosphorus that adsorbs to lake sediments can easily be disturbed and re-suspended in the water column, creating the potential to be converted to an orthophosphate ready for uptake by plant life. (BASIN, 2007) The EPA has made recommendations for concentrations of phosphorus compounds in water. These national recommendations are recorded in total phosphorus: Total phosphates should not exceed 0.05 mg/l (as phosphorus) in a stream at a point where it enters a lake or reservoir. Total phosphorus should not exceed 0.1 mg/l in streams that do not discharge directly into lakes or reservoirs. Sources of Phosphorus In the Lake Champlain Basin, sources of phosphorus are numerous and poorly regulated. The Lake Champlain Basin Program is attempting to impose a TMDL of phosphorus to the lake. This TMDL would regulate outputs from point and nonpoint sources of phosphorus. Point sources are single, localized sources, while nonpoint are 3

4 4 from diffuse sources. These sources stem from agriculture, urban development and industrial processes. Each watershed within the basin uses land in variable ratios; therefore, daily loads are considered for land use types and applied to the ratio within each watershed (LCBP-TMDL, 2003). Remediation efforts focus on urban and agricultural land use because they are the main contributors of phosphorus. Roads and development contribute to phosphorus loading as well, because paving over land reduces soil cover and infiltration. Soil and plants function as reducers of nutrients in runoff as they incorporate phosphorus and nitrogen into their cell structures. It is currently estimated that less than 10% of the total phosphorus in the lake comes from point sources. In comparison to the inputs from agricultural and urban areas, 10% does not seem overwhelming. However, point sources can be more easily identified and regulated than non-point sources. Point sources have been ineffectively regulated for the past 20 years and many facilities continually fail to meet the daily load allotments (LCBP Phosphorus-Point Sources, 2008). Point sources of pollution are often industrial pipes. In the context of this study, industry includes: paper mills, landfills, and metal smelters. The 96 wastewater treatment plants and the 5 fish hatcheries in the Basin are point sources as well (LCBP.org), but considered separately from industry. Industrial point sources are highly regulated by the EPA, but are still a major source of phosphorus in the lake. Point Source Rankings: Table 1: Point Sources of Phosphorus Effects Filter Marinas WWTP Dams Hatcheries Industrial External Link Importance Wastewater Treatment Plants Wastewater Treatment Plants as a source have been assigned a ranking of 1. Half of the 60 wastewater treatment plants in the Lake Champlain Basin have been recently upgraded, resulting in total discharge below the regulated limit of 55.8 metric tons per year (VCCAP 2010). While the Vermont WWTPs are highly regulated, New York WWTPs are not regulated by a TMDL. New York state has also been updating their facilities with new, phosphorus removing technology. Quebec s wastewater plants must not exceed a 1.0 milligrams of phosphorus per liter limit in their discharge (LCBP-Point Sources). Limited regulation in New York may lead to significant loads of phosphorus. Before intensive regulations were put into effect in Vermont, wastewater discharges were contributing half of the total phosphorus load to the lake (VCCAP 2010). Treatment plants, according to the National Research Council, release phosphorus in the dissolved 4

5 5 form. The dissolved form is most readily available to plants, and therefore of especially high concern when considering algal bloom potential. Due to the uncertainty of regulation in New York and that WWTPs release the most reactive form of phosphorus, treatment plants are assigned a ranking of 1(Table 1). Hatcheries According to the Lake Champlain Basin Program, the fish hatcheries in the Basin discharge phosphorus to Lake Champlain (LCBP Phosphorus - Point Sources, 2008). This phosphorus comes from the fishes feed, excrement, and dead carcasses (Withers, 2008). Because of this, we have linked fish hatcheries as a source of phosphorus in the effect links filter. Since fish hatcheries are a point source, the discharge from these facilities is regulated by the state of Vermont. This ensures that phosphorus emitted from hatcheries is kept at concentrations low enough to prevent phosphorus from becoming a pollutant in the surrounding ecosystems. Therefore, we have decided to assign hatcheries a 0.5 value for the effect importance matrix as a way to show that, while hatcheries have a real effect on phosphorus levels, it is not an important effect. Industrial For the purposes of this report, industry is defined as facilities such as paper mills, metal smelters, and landfills, and is identified as a point source of phosphorus by the LCBP (LCBP Phosphorus - Point Sources, 2008). According to the EPA, industry can pollute surface waters with excess phosphorus either from stormwater runoff, wastewater from the facility that connects to the municipal sewer system or wastewater that is directly discharged to the surface water (EPA, 2011). While we agree that there is a link between industry and phosphorus, we believe that industry is not a significant source of phosphorus due to the small number of industries in the Basin and because of the EPA regulations that they must follow. The EPA has created the National Pollutant Discharge Elimination System (NPDES), which requires industries to have permits for the different ways in which wastewater is emitted from a facility. Because of these extensive permit systems, the EPA is able to regulate how much waste is emitted from a site and can require a facility to follow preventive measures such as pre-treatment programs (EPA, 2011). These regulations, however, do not always ensure that an industry is releasing acceptable levels of phosphorus. The acceptable level of discharge may also change as more data on wasteload allocations is made available. The current TMDL for Lake Champlain identifies several industries within the basin, such as Burlington Electric, IBM, and the South Burlington Airport, and proposes stricter wasteload allocations for these facilities. Under the new TMDL, both Burlington Electric and IBM would still be within the allowable limit of wasteload, but the airport would not (VT ANR, 2002). These considerations have led us to assign a 0.5 ranking for industry in the effect importance filter, indicating the real, but less important effect of industry on phosphorus pollution. Nonpoint Sources 5

6 6 Nonpoint sources are more difficult to accurately measure than point sources and include agricultural land, urban/developed land, roads, forests and recreational parks. Runoff from nonpoint sources contributes more than 90% of the phosphorus in Lake Champlain. It is estimated that 46% of the nonpoint source phosphorus load is from urban land uses and about 38% is from agricultural land, with the remaining 16% split among roads, forests and sources that have not been thoroughly studied due to their minimal inputs (Table 2). It is necessary to evaluate the actual land use percentages when considering the phosphorus inputs to the lake by these sources. Urban land is only 5% of the actual land use within the Basin, yet it is a prolific phosphorus contributor. Agricultural land accounts for 14% of land use within the basin. Forested land makes up 66% of the land use in the basin while contributing only 15% of the nonpoint source phosphorus to the lake. (LCBP Phosphorus-Nonpoint Sources, 2008) Table 2. Phosphorus Loading by Nonpoint Source Land Use in the Lake Champlain Basin, 2008 Nonpoint source rankings: Table 3. Nonpoint Sources of Phosphorus Effects Filter 6

7 7 Agriculture Urban Roads Forest Parks Link Importance Agriculture Agriculture received a ranking of 1 in effects importance filter. Agricultural land, as mentioned above, is only 14% of land use within the basin. Major contributors of phosphorus are fertilizers and erosion of sediments, which contain phosphorus. Best Management Practices (BMPs) to reduce erosion and regulate fertilizer application rates are increasingly employed on farms. These BMPs have successfully reduced the load from agricultural lands. While agricultural land contributes 38% of the phosphorus from nonpoint sources, urban land contributes 46%. The difference in these percentages becomes increasingly significant when considering total land cover of the two land types. Urban land covers 5% of the basin. That is about ⅓ the percentage of land that agriculture covers (14%). Phosphorus in nonpoint source loads, such as agriculture, is mostly in the particulate form and therefore not readily available to plants. In the particulate form, phosphorus is more likely to settle out of the water column into lake sediments where it is less likely to affect the ecosystem (National Resource Council, 2000). Urban While urban land constitutes only 5% of the land use in the Basin, it contributes 46% of the load of phosphorus in the Basin. On average, urban and suburban land contributes up to four times the phosphorus per unit area than either agricultural or forested land. In urban areas, phosphorus can be attributed to sources such as fertilizers, increased erosion, loss of soils, and increased stormwater runoff due to imperviousness. Because of these factors, the soil s ability to adsorb/absorb phosphorus is nearly nonexistent and the pollutant quickly and readily runs off the land with the flow of water (LCBP - Phosphorus nonpoint sources, 2008). Urban development causes physical changes to river systems and other natural filters such as wetlands. A number of studies have shown that stream ecosystems become impaired when as little as 10-15% of the catchment area is occupied by impervious surfaces (Withers, 2008). It is due to these impervious surfaces that urban land is such a great contributor of phosphorus and other pollutants. Because urban land takes up such an insignificant amount of land area but is such an enormous contributor to the transport of phosphorus, urban land has been assigned an importance ranking of 2. It should be noted that this score is two times greater than that of agricultural land, thus demonstrating the magnitude of its effect. Roads In this assessment, roads are considered a separate source than urban land, which is different from the Lake Champlain Basin report. According to the LCBP, roads contribute phosphorus by preventing soils from naturally filtering water and sediment 7

8 8 such as rain and snowmelt, which could contain phosphorus. Activities such as washing cars on roads are other ways in which roads contribute phosphorus (LCBP Phosphorus - Nonpoint Sources, 2008). Both the construction of roads and roads themselves can also cause erosion, with eroded sediments often ending up in nearby surface waters. This further adds to road s impact on phosphorus, as eroded material contains significant amounts of phosphorus. In addition to paved roads, gravel roads can also be sources of phosphorus if they are not maintained. This is because these roads directly contribute eroded sediment during a rainstorm or storm melt, depositing these sediments in roadside ditches which directly deposit into streams, lakes, or wetlands. This issue has been confronted in Vermont through the creation of the Better Backroads Program. This program assists towns that maintain these roads with erosion control and maintenance techniques. (Clean and Clear - Better Backroads, 2004) Due to the education of the public regarding proper road maintenance, we have assigned roads a 0.5 ranking in the effect importance matrix. We believe that while roads are linked to phosphorus loads, they are not a significant source because of preventative measures that people have taken within the Basin to reduce road s impact as a source. Forests Forests are identified as sources of phosphorus since this nutrient naturally occurs in vegetation and in sediment. However, the Lake Champlain Basin Program has found that while forests cover two thirds of the Basin, they contribute only 15% of the nonpoint phosphorus load to Lake Champlain (LCBP - Phosphorus non-point sources, 2008). Forests become sources of phosphorus when phosphorus bound sediments end up in streams due to erosion. This is only problematic if a large amount of sediment is eroded, which typically happens due to anthropogenic factors such as logging. According to the LCBP, only 1% of the Basin s commercial forests are harvested each year, and therefore forest activities are a very small source of phosphorus (LCBP - Phosphorus non-point sources, 2008). We acknowledge that there is a link between forests and phosphorus by assigning forests a 1 in the effect link matrix, but have decided to rank the importance of forested areas as a 0 due to the small percentage of phosphorus from forests per land area. We believe that the land area of forests would result in forested areas getting a greater impacts value if they were assigned any value. Parks It has been acknowledged that parks may be a source of phosphorus entering Lake Champlain due to both the use of fertilizers on park property, as well as the possibility of erosion. Additionally, animal waste has the ability to contribute to overall phosphorus loading when it is left to leach into the soil and run off the land. However, because there is little data available regarding phosphorus in parks, and many parks in the Lake Champlain Basin are forested, it is concluded that parks should receive an importance ranking of 0.5. While it should be recognized that parks might contribute some phosphorus to the lake, the amount is hardly significant and is not considered to be a very important contributor of the pollutant. 8

9 9 Habitats Impacted by Phosphorus Table 4. Habitats Impact from Sources Filter Link Importance Shallow <6' 1 2 Deep >6' 1 1 Lakes/Ponds 1 1 Rivers/Streams 1 1 Developed 0 0 Forest 0 0 Herbaceous 0 0 Agriculture 0 0 Wetlands 1 1 Open Water Lake Champlain waters less than 6 feet deep are far more prone to algal blooms than waters greater than 6 feet. Because water that is less than six feet deep is warm and nearly still, phosphorus becomes bound in sediment. Because this sediment is frequently disturbed, phosphorus is often re-suspended and available for uptake by algae. Thus, we assigned areas of Lake Champlain less than six feet deep an importance ranking of 2. In deeper, colder waters of the lake (greater than 6 feet), phosphorus becomes more dispersed and precipitates into sediments where it becomes bound and relatively immobile. However, there is a large amount of phosphorus stored in the sediments below deep water, and if disturbed, has the ability to be released back into the water column, with the potential to be converted and cause algal blooms. Therefore, areas of the lake deeper than six feet have been assigned an importance ranking of 1 (Lake Champlain Basin Atlas - Human Health Issues, 2008). Rivers and Streams It was determined from data collected by the Lake Champlain Basin Program and the Vermont Agency of Natural Resources (VT ANR) that rivers and streams are major habitats affected by phosphorus. Rivers and streams are the main pathway by which phosphorus reaches Lake Champlain, thus they are being heavily studied to better understand the various ways in which they transport phosphorus. Rivers and streams not only transport phosphorus through direct runoff from areas such as agricultural land, but can also deposit phosphorus through erosion of phosphorus-containing sediment. As a 9

10 10 result, researchers are trying to better understand how riparian buffer can stop phosphorus from getting into waterways, and to understand the geomorphology of streams throughout the area. This will allow for stakeholders to get a better sense of which waterways are more prone to erosion. According to the most recent TMDL, 6,800 miles of streams and rivers have been assessed using orthophotos, topographic maps, geographic information systems, and quick observation surveys. Additionally, 1,425 river miles have been more rigorously assessed through on-the-ground observations. This information will be used to identify which streams are impaired and in need of restoration to reduce erosion. (VCAPP, 2010) To address the need to protect river and stream habitats, the Vermont Agency of Natural Resources has created an action plan called the Clean and Clear Action Plan. According to this report, controlling phosphorus around waterways through preventing encroachments is far more effective than restoring already unstable waterways. However, of the 1,425 river miles already assessed, 74% have been confined so that they have become deeper and straighter, which prevents access to floodplains and increases erosion. (VCAPP, 2010) This data indicates waterways as a high restoration priority, and therefore a 1 has been assigned for the impacts filter, indicating that phosphorus has a significant impact on rivers and streams. Other Lakes and Ponds Several other major lakes exist within the Lake Champlain basin and the quality of these lakes must be taken into consideration when assessing the impacts of phosphorus. In general, water consists of 7% of the land cover within the basin (LakeNet, 2004). While this small percentage of total land cover might give lake habitats a lower importance ranking, this habitat is still of concern because of its importance to stakeholders who live in lake regions, such as in upstate New York. Lakes in this region contribute greatly to tourism and recreation, and are often used by residents as sources of water. These factors resulted in lakes and ponds receiving a 1 in the impacts filter. Overall, it appears that most of the lakes in the basin do not have a problem with excess phosphorus. This is partly due to the land use of the areas around most of the lakes. Especially on the New York side, most of the land surrounding the lakes is state owned land, and so there are less human inputs of phosphorus going into these lakes. This reduces the stress put on the lakes, and prevents phosphorus from reach high levels. Wetlands Wetlands, dependent upon season, hydrology and type, can be considered either a source or a sink of phosphorus. When wetlands are located near or on agricultural landscapes they accumulate phosphorus, which results in a gradual release of phosphorus. Thus these wetlands become a source of nutrients. Wetlands act as sinks of phosphorus when the location of agriculture in the buffer area of wetlands would reduce the contribution of agricultural phosphorus to the overall watershed loading (Weller, Watzin, & Wang, 1996). In other words, when the wetland is located at a great enough distance to agricultural run-off, it will absorb phosphorus run-off and act as a sink, not a source. Shallow waters may be comparable to open lake areas less then 6 deep, but since there is 10

11 11 intensive vegetation and hydric soils, blooms do not occur as phosphorus is absorbed by the system until the soil is saturated with phosphorus. After saturation, phosphorus is carried out into moving water (Richardson). Wetlands are often created to reduce phosphorus transportation from point sources or waste water treatment systems (LCBP Phosphorus - Point Sources, 2008). Due to the ability of wetlands to absorb and retain phosphorus, the Clean and Clear Program has dedicated over $1 million to wetland protection and restoration projects since Additionally, the Wetlands Reserve Program (WRP) has received federal funding as a result of the 2008 Farm Bill, which works to restore and protect existing wetlands (Vermont Clean and Clear Action Plan, 2010). Riparian wetlands have the greatest potential for improving phosphorus loading into surface water because of their close proximity to the stream network results in extensive interaction with both stream water and surface water runoff (Weller, Watzin, & Wang, 1996). Wetlands are assigned a rank of 1 for importance because although they do contribute some phosphorus to open water when they are within close proximity to agricultural fields, they also have the ability to retain phosphorus and prevent it from reaching open bodies of water. Conclusions / Recommendations: Our findings show that non-point sources of pollution from agriculture and urban development are still major contributors of phosphorus in Lake Champlain. Efforts have been concentrated in reducing these non-point sources, however much still needs to be done to achieve the TMDL for Vermont in Lake Champlain. Some ways to achieve reduced phosphorus loads include more widespread and better education for the public about the impacts of phosphorus, and implementation of more stringent regulations and Best Management Practices for farms, businesses and industry. Additionally, our research indicates that the habitats most affected by phosphorus are aquatic; specifically rivers, streams, lakes and ponds. Phosphorus is most damaging in water less than six feet deep as shallow water bodies are the most susceptible to toxic algal blooms (Lake Champlain Basin Atlas - Human Health Issues, 2008). Because of this, these areas should be considered at highest risk to phosphorus impacts and should be the most closely monitored in the future. In this phosphorus specific portion of the overall EcoRA, roads were considered under urban land use. The Lake Champlain Basin Program considers roads in urban land use and therefore all relevant road data was summarized into urban totals, which were not discernable. It was therefore difficult to differentiate the amount of phosphorus actually coming from roads since they were lumped in with the rest of developed areas. Through our research we realized the need for more intensive consideration of phosphorus from varying types of agricultural land. Dependent upon the crops grown, the fertilizer usage and uptake varies. Buffer zones between agriculture and waterways will act as a filter, removing phosphorus by trapping it in soil before it reaches the water. Wetlands often act as buffers as well, but the removal of phosphorus varies, and is highly dependent upon type, hydrology and season. Due to the impact of agriculture and development on streams, it is recommended that rivers and streams be broken down by proximity to agricultural and developed land. 11

12 12 Of course, the more detailed view we suggest would require more time, and as a result more costly. The relative risk model that was completed is a good overview to qualify sources and habitats according to a very general, high, medium, or low risk potential. More intensive study would be suggested for programs or organizations that might be solely considering one particular source or habitat. Acknowledgements We would like to thank Eulalia Ishee for sharing her knowledge and resources on phosphorus for this project, as well as Eric Smeltzer for sharing his extensive information on phosphorus in the Basin. We would also like to thank the ENSC202 class for their continual input. Finally, we thank Breck Bowden, Pooja Kanwar and Pamela Johnson for their guidance throughout this process. 12

13 13 Citations "BASIN: General Information on Phosphorus."(April, 2007) Boulder Community Network. Retrieved from Clean and Clear - Better Backroads. (2004). Clean and Clear Action Plan. Retrieved from EPA. Industrial and Commercial Facilities. (2011). National Pollutant Discharge Elimination System: Home. Retrieved from Gaddis, Erica J.B, and Alexey Voinov. "Spatially Explicit Modeling of Land Use Specific Phosphorus Transport Pathways to Improve TMDL Load Estimates and Implementation Planning." Water Resources Management June 2010: EBSCOhost. Web. 2 Mar "LAKE CHAMPLAIN BASIN ATLAS: Phosphorus - Human Health Issues" (2008). Lake Champlain Basin Program: Home. Retrieved from "LAKE CHAMPLAIN BASIN ATLAS: Phosphorus - Nonpoint Source." (2008). Lake Champlain Basin Program: Home. Retrieved from "LAKE CHAMPLAIN BASIN ATLAS: Phosphorus - Point Sources." (2008). Lake Champlain Basin Program: Home. Retrieved from "Lake Champlain Basin Program: TMDL Program." (2003). Lake Champlain Basin Program: Home. Retrieved from LakeNet (2004). Lake Profile: Lake Champlain. Retrieved from Mueller, D. K., Helsel, D.R. "USGS NAWQA CIRC1136 Nutrients in Nation's Waters." (November, 2009). USGS Water Resources of the United States. Retrieved from National Research Council Watershed management for potable water supply: Assessing the New York City strategy. Commission on Geoscience, Environment and Resources. National Academy Press. Washington, D.C. Richardson, J. L., and Michael J. Vepraskas. (2001). Wetland Soils: Genesis, Hydrology, 13

14 14 Landscapes, and Classification. Boca Raton, FL: Lewis. Schueller, Gretel. "A Lake in Distress." National Wildlife Aug. 2005: EBSCOhost. Web. 1 Mar Smeltzer, Eric et al. (2009). Lake Champlain Phosphorus Concentrations and Loading Rates, (No. 57). Retrieved from "The Nature and Properties of Soil" by Nyle C. Brady and Ray R. Weil, Prentice Hall, Inc., 1996, Upper Saddle River, NJ 07458; ISBN: , 11th Edition. VCCAP(2010). Vermont Clean and Clear Action Plan Annual Report, Vermont Agency of Natural Resources and Vermont Agency of Agriculture, Food and markets: 102pp. Vermont Agency of Natural Resources. Revised Implementation Plan: Lake Champlain Phosphorus TMDL. January 15, Vermont Agency of Natural Resources and New York State Department of Environmental Conservation. Lake Champlain Phosphorus TMDL. September 25, VT ANR (2010). Revised Implementation Plan, Lake Champlain Phosphorus TMDL, Vermont Agency of Natural Resources. submitted to the Vermont General Assembly in accordance with Act 130 (2008), Section 2, January 15, Withers, P.J.A. and H. P. Jarvie (2008). Delivery and cycling of phosphorus in rivers: A review. Science of the Total Environment, 400(1-3), Windhausen, L.J., Braun, D.C., and Wang, D., A Landscape Scale Evaluation of Phosphorus Retention in Wetlands of the LaPlatte River Basin, Vermont, USA. 14