House Transportation hears DEC and VTrans briefings on municipal-road stormwater rules and state stormwater permitting

The House Transportation Committee on Feb. 27 heard separate briefings from the Vermont Department of Environmental Conservation (DEC) and the Vermont Agency of Transportation (VTrans) on municipal-road stormwater standards, inventory work and the agency's responsibilities under statewide stormwater permits.

Chad McGahn, with the DEC Municipal Roads Program, told the committee the MRGP (Municipal Roads General Permit) flows from the Clean Water Act and the Lake Champlain TMDL and is aimed at reducing phosphorus from municipal roads. “The core of the municipal roads program is, mitigation of, stormwater on, different elements of transportation,” McGahn said, adding that the permit focuses on open-drainage gravel roads where undersized or mislocated culverts and missing drainage infrastructure amplify erosion after major storms in 2023 and 2024.

The permit requires towns to enroll and to complete a road erosion inventory using an Esri Survey123 app, McGahn said. The program establishes an implementation schedule that targets 7.5% of noncompliant segments per year and a 20% improvement rate for very-high-priority segments measured from each town's baseline inventory. McGahn said roughly half of municipal roads statewide are considered hydrologically connected and therefore jurisdictional under the MRGP.

Joel Perrigo, Municipal Assistance with BTRANs (Better Roads and Grants & Aid), joined the discussion to clarify funding: work that affects water quality is prioritized for Better Roads/BTRANs funding, and towns or RPCs can seek to have segments deemed jurisdictional so they qualify for clean-water funding. McGahn noted reassessments and storm-damage documentation are part of the second cycle of the inventory, and said the program gives feasibility exemptions for constrained locations (for example because of wetlands, utilities or protected trees).

Committee members asked how many towns have performed reassessments and how the inventory data translate into grant awards. McGahn said the map of documented implementation best reflects towns that are actively engaging; towns without map points either have not engaged or are behind on documentation. He also said the second-cycle reassessment questions now focus on the presence of active erosion (an indicator of drainage problems) rather than only whether a practice is present.

Jennifer (Jenny) Gallahan and Tyler Hansen of VTrans' maintenance division briefed the committee on VTrans' stormwater responsibilities under the state’s transportation separate storm sewer system permit (TS4). Gallahan said TS4 consolidates the agency’s stormwater permitting requirements, including MS4-related work in higher-population areas, the Multi-Sector General Permit (MSGP) for industrial sites (such as airports and gravel pits), and post-construction operational stormwater permits for projects that create new impervious surface.

“We have 92 of those [post-construction] practices located around the state,” Gallahan said, referring to retention/management practices such as ponds and basins; VTrans inspects these annually and reports maintenance to ANR. VTrans staff explained the TS4 permit is statewide for VTrans-owned infrastructure, while municipalities subject to MS4 rules comply under separate municipal MS4 permits.

On TMDL-related work, VTrans described multi-year phosphorus control plans and four-year implementation cycles. Gallahan said the agency submitted a generalized statewide phosphorus control plan and required four-year implementation plans; the plans are intended to implement 25% of the agency's phosphorus-reduction target per cycle. As of the end of the 2023 construction season, VTrans reported it had implemented more than 28% of its target.

Committee members pressed for evidence that road-focused practices reduce measured phosphorus concentrations in receiving waters. McGahn said data exist to apportion municipal-road contributions to overall phosphorus loads but did not provide site-level, pre/post monitoring results during the hearing and offered to follow up with available studies and data.

Members also raised maintenance and resilience concerns for stormwater practices installed on gravel roads, including how rapidly stone aprons and ditch linings fill with sand after storms and the long-term maintenance burden on towns. McGahn and VTrans staff described guidance for recurring-sediment situations: reestablish conveyance by removing some stone, place stone aprons at outlets, and hydroseed tops of ditches so vegetation can stabilize the repair; they said the reassessment guidance was updated to account for situations where grass-dominated ditches cover underlying stone installations.

The presenters said deadlines and targets are staggered: road-erosion-inventory reassessments for the MRGP second cycle are expected to be completed by Oct. 31, 2027, and longer-term program goals aim for broad compliance by the program’s 2036 target dates. VTrans said the Lake Memphremagog phosphorus control plan was being finalized and is due to the Agency of Natural Resources on April 1 (year discussed in testimony); the agency expects to implement the plan on the timetable required by ANR.

No formal committee votes were taken during the presentations. Several representatives asked for more detailed follow-up information — including specific grant-application fulfillment rates, the amount of the annual municipal MRGP fee (not specified in the briefing), and empirical monitoring showing reductions in phosphorus after specific road projects — and presenters agreed to provide additional materials after the hearing.

The committee paused to take a scheduled break and planned follow-up discussion of bills and agenda items at a later time in the session.