The Northwest Regional Planning Commission, with support from the DEC’s Ecosystem Restoration Program, recently completed a multi-part project that focused on targeting priority nonpoint source pollution in the St. Albans Bay watershed. The project evaluated erosion and runoff from transportation infrastructure (roads, bridges, and culverts) and stormwater runoff from developed land. The project consisted of three components: compile a list of recommended non-agricultural projects that address nonpoint source pollution based on previous studies; inventory current road related stormwater projects outside the Stevens Brook and Rugg Brook stormwater impaired watersheds; and, conduct a mapping analysis of potential critical source areas at the watershed level.
For part one, the Regional Planning Commission (RPC) reviewed 18 studies that have been conducted in the watershed since 2003 and interviewed several municipal and state agency staff to compile a list of projects that had been recommended to address nonpoint source pollution. In total, 60 projects were identified from past non-agricultural studies and only 15 of these had been completely implemented. There are two sites where part of the recommended project has been implemented but additional treatment or restoration can be constructed.
For part two, the RPC evaluated municipal culvert inventories, stream geomorphic assessment data and town bridge inspection reports to identify potential municipal bridge and culvert projects within the study area. Based on available data, culverts and bridges in the watershed were highlighted as needing possible attention if it had been identified as having a known issue (poor condition, signs of erosion present, etc.) as well as the potential for erosion (undersized). Overall, 41 potential projects were identified in the watershed area: 38 culverts and 3 bridges.
For part three, the RPC developed and relied on a methodology to identify areas within the St. Albans Bay watershed that may be more likely to generate runoff and erosion as well as contribute sediment and phosphorus to the Bay. The identification of these potential critical source areas (CSA) or areas where the potential contribution of pollutants (i.e. sediments, phosphorus) to the receiving water is significantly higher than the other areas will aid in focusing nonpoint source-related implementation efforts that can be conducted in the future. An additional aim of this exercise is to develop a methodology that is based on readily accessible data and spatial overlay mapping methods which could be applied by watershed managers and planners for other areas in Vermont and the Lake Champlain drainage basin.
The benefit of this project is that its findings can be helpful to landowners, towns and interested groups within the watershed when defining and proposing water quality improvement and protection projects. The next steps in using outcomes from the project will be to determine whether uncompleted prior recommended projects can move forward; to assign implementation priority for the 41 culvert and bridge projects; and, to use potential critical source area information when making land use or land management decisions.