Reducing Phosphorus Pollution

The Goal

Reduce phosphorus inputs to Lake Champlain to promote a healthy and diverse ecosystem and provide for sustainable human use and enjoyment of the Lake.

// In This Section //

• Introduction
• Sources of Phosphorus
• The Lake Champlain Phosphorus Total Maximum Daily Load
• Adaptive Management
• Threats: Urban and Rural
• Phosphorus Reduction Efforts in Missisquoi Bay
• Progress
• Introduction to the Phosphorus Objectives, Priority Actions, and Tasks
• The Implementation Role of the Public
• Role of the LCBP in Achieving these Objectives
• Citations

Introduction

As in all living systems, the balance of nutrients within the Lake Champlain ecosystem is critically important in maintaining the condition of the Lake. If the concentrations of nutrients are significantly altered, the ecosystem will become unbalanced and noticeable changes in Lake condition will result. Like most lakes in the northeast, the concentration of phosphorus in Lake Champlain is a key factor in determining the quality of the ecosystem as humans have come to know and enjoy it.

Phosphorus is typically known as the limiting nutrient in a lake ecosystem, meaning that algal growth is limited by the amount of phosphorus that is available. Algae require other nutrients as well, but phosphorus is commonly the one nutrient that is most needed. When phosphorus is available in excessive amounts, more algal growth than usual may result, including unsightly algae blooms. These changes in plant growth, in turn, can affect many other aspects of the Lake ecosystem, including the amount of oxygen in the water, the types of fish we catch, the smell, the appearance, and potability of the water itself.

Residents and visitors to the Basin can take many actions to reduce the phosphorus load carried by streams to Lake Champlain. The Lake Champlain Basin Program (LCBP), together with its governmental partners, has identified a number of specific actions that are most needed to protect the lake. These actions are provided in the tables at the end of this chapter, accompanied by the intended schedule for their implementation.

Back to Top

Sources of Phosphorus

Phosphorus is most commonly found attached to soil particles and may be released into the water column when soils are disturbed. Phosphorus typically arrives in Lake Champlain bound to sediments carried down rivers and streams or as dissolved phosphorus that has been released from the sediments into the water column. For purposes of this plan, phosphorus pollution is grouped into two general categories. The most obvious category is point source pollution, in which pollutants can be directly attributed to a tangible source in a particular place – a wastewater treatment plant, for example. Point source pollution accounts for about 5 percent of the total load reaching Lake Champlain. The second category, while less obvious, is currently the more important problem in the Lake Champlain watershed, about 95 percent of the total phosphorus load (Smeltzer et al. 2009), and is called nonpoint source pollution. Nonpoint source pollution is associated with discharges of stormwater and snowmelt and is produced across a broader geographical region. Examples include soil erosion and runoff from agricultural fields; stormwater washing off roads, lawns, and parking lots; and unstable streams and stream bank erosion from modified water flows. Because the exact origin of nonpoint source phosphorus cannot easily be identified, it is much harder to control. Management actions to address nonpoint source phosphorus pollution are addressed in this chapter.

Recent research in the Lake Champlain Basin shows that, acre for acre, developed land contributes up to four times more nonpoint source phosphorus than average agricultural lands and seven times more than forests (Troy et al. 2007). However, far more acres of Basin land are in agriculture and forests than in urban settlements; it is now clear that substantial reductions in nonpoint phosphorus runoff are required in both agricultural and developed lands in order to meet our targets for a clean Lake Champlain. Developed lands contributed about 46 percent of the phosphorus runoff Basin-wide in 2001, and agricultural lands contributed about 38 percent. These proportions, however, vary greatly among the various sub-watersheds. For example, in 2001 developed land was the largest contributor to phosphorus in Burlington Bay, Vermont (about 99 percent) and Cumberland Bay, New York (about 57 percent). But agricultural land contributes the majority of phosphorus load to the Missisquoi Bay, Vermont and Québec (about 64 percent) (Troy et al. 2007).

Back to Top

The Lake Champlain Phosphorus Total Maximum Daily Load

The Lake Champlain phosphorus total maximum daily load (TMDL) provides the fundamental phosphorus management framework for the Lake. The TMDL defines the maximum amount of phosphorus loading that the Lake can receive and still achieve the in-Lake phosphorus concentration criteria established for each segment of the Lake. Because the TMDL for phosphorus is exceeded in numerous parts of Lake Champlain, a TMDL plan has been developed to reduce in-Lake phosphorus concentrations to the maximum allowable levels. This TMDL Plan identifies the total phosphorus-loading capacity among the various sources of phosphorus and includes implementation plans for Vermont and New York to achieve the necessary phosphorus reductions over time, to reduce phosphorus concentrations to the TMDL level in the Lake. The TMDL establishes individual waste load allocations for each wastewater treatment facility in Vermont and New York and defines phosphorus allocations for agricultural, developed, and forested land in each sub-watershed draining to the lake. The Lake Champlain Phosphorus TMDL was developed jointly by Vermont and New York under the US Clean Water Act, and was approved by the US Environmental Protection Agency (USEPA) in 2002. Vermont issued a revised TMDL Implementation Plan in 2010.

Back to Top

Adaptive Management

The LCBP and partners support a formal adaptive management approach to reducing phosphorus loadings into Lake Champlain. This approach is not new to the LCBP, but with the development of a formal adaptive management plan for the Basin, resource managers will be able to more accurately assess the effect of different programs in reducing phosphorus pollution in the Lake. Adaptive management is a structured approach to making decisions about managing the Lake that will incorporate both experience and careful projections about the effectiveness of management policies based on the best science and professional judgment available. A well-designed adaptive management plan assesses specific ecological indicators that inform managers about how the ecosystem has responded to the management actions. Management actions are continually evaluated to determine how effective they are at reducing phosphorus loading. Managers can then modify actions to further improve phosphorus reduction or shift support to other practices that may be more effective at reducing phosphorus pollution. A more detailed description of the overall adaptive management process for Lake Champlain can be found in Chapter 2, A Strategy for Implementing the Plan.

Back to Top

Threats: Urban and Rural

Numerous and diverse threats challenge water quality in Lake Champlain. Threats are attributable to human actions – our actions – on the landscape and encompass a wide variety of activities, such as: failure to manage and/or treat stormwater runoff from existing or new areas of developed land (residential, commercial, and industrial), poor management of cropland and pasture, loss of forests and wetlands, development encroachment on stream banks and shorelines, road construction and maintenance practices, and inadequate wastewater treatment.

Similar to the diversity of threats to water quality in Lake Champlain, there is a wide range of strategies that can be employed to reduce phosphorus pollution. Examples include:

• implement a suite of voluntary and regulatory programs at the state/provincial and municipal levels to address stormwater runoff;
• provide technical and financial assistance to farmers to support implementation of recommended best management practices;
• use regulation, zoning, and incentives to prevent conflicts between infrastructure and streams and rivers;
• provide financial and technical assistance to support forest stewardship, wetland protection, and restoration efforts;
• improve the ability of financial assistance programs, including the state revolving fund, to target phosphorus reduction projects; and
• implement a suite of best management practices for roadways that specifically address drainage, maintenance, and erosion control.

These strategies involve one or more of the following policy tools:

• regulatory requirements that provide specific steps that must be taken to control pollution and reduce impacts;
• financial incentives that link funding eligibility to specific actions or use subsidies to control pollution and reduce impacts; and
• technical assistance that supports sharing information on water-quality impacts and suggests techniques to reduce impacts.

Back to Top

Phosphorus Reduction Efforts in Missisquoi Bay

Blue-green algal blooms have become a forefront issue in Missisquoi Bay since the 1990s. Severe algal blooms in Missisquoi Bay have inhibited recreational activities during the busy summer months in several recent years and have impacted access to the bay in both Québec and Vermont. The impacts of these algal blooms are of binational concern, leading to the creation of a formal agreement between Québec and Vermont, commonly known as the 60/40 agreement, in which the State of Vermont has agreed to assume 60 percent of the responsibility for reducing phosphorus loading to the bay, and Québec will assume 40 percent of the responsibility. The International Joint Commission (IJC), an organization established by the 1909 Boundary Waters Treaty between the federal governments of the United States and Canada, also provides support for reducing phosphorus loads.

The LCBP and its partners have made numerous efforts to reduce phosphorus loads into Missisquoi Bay in recent years. The Rock River watershed, a sub-watershed of Missisquoi Bay, has been targeted as a short-term focus area for expanded outreach and implementation efforts. Significant resources have been allocated to research and implementation of new management programs to minimize the impacts of different land uses in this watershed. A recent LCBP-funded project by researchers at the University of Vermont developed an accounting system to track nonpoint sources of phosphorus in this watershed. A new project targeting the Rock River watershed will provide incentives to farmers to initiate best management practices on their farms to reduce pollution due to runoff. Resource managers in the Province of Québec recently completed a successful “Green Buffers” project, which encouraged farmers to plant perennial crops within nine meters (30 feet) of the water’s edge along the riparian corridors of their fields. These crops provide a buffer to waterways adjacent to agricultural fields during the growing season while also providing a source of income for the farmer.

Current LCBP-funded projects range from identifying specific sources of phosphorus within the Missisquoi Bay Basin, examining the impacts of sedimentation due to stream bank erosion, evaluating the effects of phosphorus loading from the sediments within Missisquoi Bay itself, and implementing small best management practices on farms within the basin. LCBP is also working with its partners to acquire light detection and ranging (LiDAR) coverage for a majority of the Missisquoi Basin. LiDAR is a remote sensing technology that uses pulses of light to determine characteristics of the earth’s surface, such as topography and land cover, and provides very high-resolution imagery. LiDAR imagery thus enables more accurate elevation models and land cover classifications than previously supported by satellite imagery. The resulting data can delineate the micro-topography of an area, such as water and pollution transport networks through ditches and gullies, and reveal more detailed land cover, such as narrow riparian buffers between rivers and agricultural fields. Many other projects, current and proposed, are identified within the lists of priority actions below.

Knowledge gained by resource managers from each of the Missisquoi Bay projects can be applied to many other sub-watersheds of the Lake, especially those dominated by agricultural land use. The LCBP will ensure that resource managers have the necessary tools and information to successfully apply knowledge gained by this work to reduce phosphorus pollution around the Lake Champlain Basin. For example, the phosphorus critical source analysis project will result in a list of landscape characteristics and management practices that combine to produce high phosphorus loads into our waterways. This project also aims to compare the results generated by complex modeling tools to those obtained by simple GIS analysis to determine if analytical efficiencies are possible and can be affordably applied throughout the Basin.

Back to Top

Progress

Major efforts have been undertaken in the last two decades to maintain good water-quality conditions in several segments of Lake Champlain and around the Basin as a whole. Burlington Bay, Shelburne Bay, and Cumberland Bay, three of Lake Champlain’s most heavily developed lakefront areas, remained below phosphorus concentration targets in most recent years. Water quality in the Main Lake, Isle LaMotte, and Otter Creek lake segments has changed minimally through the last two decades despite sustained conversion from agricultural and forest lands to developed lands. Phosphorus loads from wastewater treatment plants around the Basin have been reduced by nearly 80 percent since 1990. Phosphorus loads from wastewater treatment plants contributed approximately 25 percent of the total Basin-wide load in 1990-1991; in 2007-2008, that number was estimated at only 5 percent. Despite increased land use conversion for development within the Basin, tributary phosphorus loads and flow-weighted mean inflow concentrations to most regions of the Lake were stable or decreasing from 1991 to 2008 (Smeltzer et al. 2009). This assessment is reflected in a recent study by the US Geological Survey (USGS) using new statistical methods illustrating that trends in phosphorus concentrations adjusted for stream flow have decreased since 1999 in fifteen of eighteen tributaries studied, suggesting that a positive response to watershed management efforts may be underway (Medalie and Hirsch 2010).

Significant challenges in achieving water-quality goals remain. For example, Lake phosphorus concentrations remained above the TMDL targets during all or nearly all years in five Lake segments. Levels were below the TMDL targets during nearly all years in two lake segments, and the remaining six lake segments had borderline conditions in which the mean phosphorus concentrations varied above and below their targets. Four Lake segments had significant increasing linear trends in phosphorus concentrations over the 1990-2008 time period; however, no Lake segment exhibited a significant decreasing phosphorus trend. Additionally, phosphorus loading rates remained above the total loading capacities established in the Lake Champlain Phosphorus TMDL in all but two Lake segments (Smeltzer et al. 2009).

Back to Top

Introduction to the Phosphorus Objectives, Priority Actions, and Tasks

The new framework of Opportunities for Action (OFA) identifies broad objectives designed to reduce phosphorus concentrations in Lake Champlain, more focused priority actions to meet those objectives, and specific tasks agreed to by OFA signatory agencies. The priority actions have been developed to collectively address the objectives that have been identified for this chapter, all of which are ultimately working toward the goal of reducing phosphorus concentrations in Lake Champlain to promote a healthy and diverse ecosystem and to provide for sustainable human use and enjoyment of the Lake. All LCBP partners are active in watershed management programs within the Basin, implementing many projects that are not described in the task lists below, and are working to achieve the objectives identified in this chapter. The tasks included with each priority action below are projects identified by the LCBP partners who have signed OFA as a comprehensive management plan for their organizations and jurisdictions to achieve within the time frames provided and to the extent that funding is available.

Back to Top

The Implementation Role of the Public

While it is essential for governments, agencies, and departments at all levels to work toward the common goal of phosphorus load reduction, it is no less important for citizens in every part of the Lake Champlain Basin to participate effectively at home and in their workplaces. The challenge of phosphorus load reduction is a responsibility of residents and visitors alike, and success can be achieved only through effective community-wide participation. For this reason, many citizen-oriented tasks directed at phosphorus load reduction are described in the Informing and Involving the Public chapter of this plan.

Back to Top

Role of the LCBP in Achieving these Objectives

The LCBP, with the help of the jurisdictional and public partners, will aggregate all phosphorus-loading data available for the Basin into a report that will provide minimal interpretation. This data report will provide policymakers in each jurisdiction access to the nutrient management criteria and an updated understanding of the phosphorus-loading pressures within the Basin.

• LCBP will use this data report to:
  • Inform the decision-making process.
  • Assess the full period of record.
  • Conduct a trend analysis using more recent data where possible:
    1. develop a mechanism to assess the current status of all wastewater treatment plants in the TMDL with respect to phosphorus loading,
    2. develop a mechanism to assess the current status of point and nonpoint source phosphorus loads using data from the Long Term Monitoring Program and other sources
    3. track changes in land use throughout the Basin on a regular basis.
• LCBP will assemble information from all partners to develop this data report and provide the report to the Steering Committee annually.
• LCBP will prioritize implementation grant proposals from nongovernmental organizations and municipalities that focus on phosphorus reduction.
• LCBP will continue to review proposals to the US Army Corps of Engineers under Section 542 of the Water Resources Development Act that focus on reductions to phosphorus and sediment loading.
• LCBP will assist in cross-boundary transfer of management practices found to be successful in other regions and applicable to the Basin.
• LCBP will support tasks identified by the LCBP Steering Committee to address immediate needs for phosphorus reduction through grants and contracts.
• LCBP will help track the success of TMDL implementation activities on both sides of the Lake
• LCBP will continue to assess phosphorus concentrations and loads by Lake segments.

Back to Top

Citations

Medalie, L. and R. M. Hirsch. 2010. Trends in phosphorus concentrations and loads in Lake Champlain tributaries 1990-2008: An evaluation using new statistical methods. Presented at the Lake Champlain Research Conference, 7 June, University of Vermont, Burlington, Vermont.

Smeltzer, E., F. Dunlap and M. Simoneau. 2009. Lake Champlain Phosphorus Concentrations and Loading Rates, 1990-2008. Lake Champlain Basin Program Technical Report # 57.

Troy, A., D. Wang, D. Capen, J. O’Neil-Dunne and S. MacFaden. 2007. Updating the Lake Champlain Basin Land Use Data to Improve Prediction of Phosphorus Loading. Lake Champlain Basin Program Technical Report # 54.

Back to Top