Clean water projects target nutrient and sediment pollution to waterbodies and improve water quality over the long term. While measured water quality parameters are the ultimate indicator of progress, it will take time for Vermont’s waters to realize the benefits of clean water projects. To provide incremental measures of accountability, CWIP estimates the pollutant reductions associated with clean water projects installed across state and federal funding programs and regulatory programs in Vermont.
The process of estimating nutrient and sediment reductions associated with clean water projects is referred to as pollutant accounting. To estimate pollutant reductions, CWIP and partners must collect many types of data on the clean water projects implemented (i.e., watershed, land use, storage volume, area treated, etc.), which is referred to as tracking. Tracking and accounting together enable CWIP to estimate the mass of pollutants reduced from projects and monitor progress towards achieving water quality goals, such as Total Maximum Daily Loads (TMDLs).
Much of the State of Vermont is covered by large TMDLs that require nutrient pollutant reductions (i.e., phosphorus and nitrogen) from nonpoint (rain/snowmelt driven) and point (end-of-pipe) sources. The Lake Champlain and Lake Memphremagog TMDLs both target phosphorus pollution to address cyanobacteria blooms (i.e., blue-green algae), as well as other excess algae and aquatic plant growth. The Long Island Sound TMDL targets the nitrogen pollution which causes low dissolved oxygen in the Sound.
There are a variety of clean water project types across various land use sectors that result in pollutant reductions. CWIP collaborates with numerous state and federal agencies to develop and implement tracking and accounting methodologies for clean water projects.
Pollution reduction estimates are modeled at the individual clean water project-level, as measuring phosphorus reductions at the project level through water quality monitoring would be cost-prohibitive. Most clean water project pollutant reduction estimates are based on the following:
- Estimated total pollutant load from land being treated, prior to treatment by a project or practice. This is based on the area of land draining to the practice or project and the average pollutant loading rate from the land use.
- The average annual pollutant reduction performance – referred to as an “efficiency” – of the project type. This is often expressed as a percent of total load reduced and is based on research of project performance relevant to conditions in Vermont.
The average annual pollutant reduction efficiency for a project is applied to the pollutant load delivered from the land draining to the project to estimate the average annual pollutant reduction. The ability to estimate the pollutant reduction of a project can be limited by lack of data on pollutant loading rates for the land treated and/or lack of information on the performance of a project in treating pollution.
To standardize and centralize tracking and accounting methods, CWIP is developing Tracking and Accounting Standard Operating Procedures (SOPs). CWIP’s Tracking and Accounting SOPs are considered draft working documents until SOPs from all land use sectors are compiled, put on public notice, and finalized to meet Clean Water Service Delivery Act (Act 76 of 2019) requirements (see below). These SOPs will also be compiled into Vermont’s Section 319 Nonpoint Source Management Program Quality Assurance Project Plan (QAPP) for U.S. EPA review and approval.
Below are the current draft tracking and accounting SOPs for regulatory and non-regulatory road and stormwater treatment projects:
- Standard Operating Procedures for Tracking & Accounting of Stormwater Permit Programs: Municipal Roads General Permit (MRGP) (June 1, 2020)
- Standard Operating Procedures for Tracking & Accounting of Stormwater Permit Programs: Operational and Municipal Separate Storm Sewer (MS4) Permits (June 1, 2020)
Phosphorus reductions cannot yet be estimated for all clean water project types, and SOPs for other land use sectors are currently under development. Please see Appendix F of the Vermont Clean Water Initiative 2019 Performance Report for a summary of Vermont’s tracking and accounting methods until full SOPs are developed.
The Clean Water Service Delivery Act (Act 76 of 2019) addresses the state’s tracking and accounting in several ways:
- The state is required to publish methods to estimate phosphorus reductions for all clean water project types in the Lake Champlain and Lake Memphremagog basins by November 1, 2021.
- The state is required to establish a schedule to publish methods for other (i.e., non-phosphorus) impairments by November 1, 2023. U.S. EPA-supported efforts are underway to coordinate and develop tracking efforts for clean water projects implemented in the Long Island Sound basin.
- After initial publication of tracking and accounting methods, the state is required to periodically review accounting methods at least every five years to determine the adequacy or accuracy of pollutant reduction values and design lives.