After years of consultations between state officials and a stakeholder group, a new stormwater management regulatory structure for Maryland appears to be taking shape.
The initiative began with the passage of SB 227 in 2021. Drafted in response to severe flooding events in Ellicott City, Rockville and elsewhere, the legislation tasked the Maryland Department of the Environment (MDE) with updating state stormwater management regulations to provide greater resiliency against changing rain patterns. In response to concerns raised by builders, developers, local government officials and others, the bill also required MDE to coordinate with a stakeholder committee while drafting the new regulations.
Formed in mid-2022, the Advanced Stormwater Resiliency in Maryland (AStoRM) committee and MDE are finally beginning to draft proposed regulations and a design manual, and those drafts are “trending in a positive direction,” said Matthew Wessel, Principal at Rodgers Consulting.
AStoRM proceedings have convinced MDE to abandon its initial plan to revise stormwater management requirements and pursue a different plan — one that would both address the need for heightened resiliency and ease a longstanding concern with Maryland’s approach to stormwater management.
MDE’s initial plan would have essentially used updated rainfall data and future rainfall projections to require developers to expand their Environmental Site Design (ESD) measures by a certain percentage.
Some stormwater management experts, however, have long argued that ESD is not an effective way to manage short-duration, high-intensity storms that have become more common in the state. ESD became a centerpiece of Maryland’s stormwater management regulations in 2010 in order to improve the quality of water discharged into the Chesapeake Bay. A study by the American Society of Civil Engineers (ASCE) since concluded that ESD is an effective management tool for long-duration, low-intensity rain, such as typical rainfall patterns in the Pacific Northwest, but is not an effective, efficient way to manage the high rain volumes produced by short, intense storms.
“Our first piece of feedback to MDE right out of the gate was now is the right time to revisit the ESD framework,” said William ‘KC’ Reed, Senior Director of Project Services at Rodgers. “ESD was heavily weighted towards water quality management rather than quantity management. If the ultimate goal of SB 227 is to improve resiliency relative to flooding, you have to reverse some of that overcorrection.”
Consequently, MDE is now drafting new regulations that would include a balance of ESD facilities to manage small, common storms and more traditional, structural stormwater management systems – such as extended detention ponds, sand filters, and large-scale bioretention ponds – to handle the volume of large, rain events.
“These regulations will take up a bit more space on a site than what was done in the past,” Wessel said. “But the increase is not nearly as drastic as it would have been using an all-ESD approach that was floated as an option earlier in the process.
Structural practices are more efficient and effective at treating larger quantities within a smaller footprint than increasing the amount of ESD.”
MDE and AStoRM are also working to ease another long-standing problem with stormwater management regulations, namely the differing requirements set by local jurisdictions.
“When the last stormwater regulations were produced [in 2010], they included a lot of language that was open to interpretation so every jurisdiction implemented the state law in a completely different way,” Wessel said. “One of the things we are working on in AStoRM is trying to make the language of the new state regulations less open to interpretation so that local governments know what the state goals are and how to implement them at a local level.”
MDE has not yet set dates for the completion and implementation of new stormwater regulations. However, Wessel and Reed expect the state to release the proposed regulations and design manual for public comment sometime in 2025.
The likely impact of the new regulations on commercial real estate developers and specific projects is also not yet known.
“I have been asked what are the real-world implications of this,” Reed said. “So far, my answer is, ‘Which county are you talking about?’”
The extent of change in stormwater requirements will largely be determined by how a local jurisdiction has been implementing current requirements.
Some counties are already largely following what the AStoRM committee is advancing, namely “limiting what happens with ESD, bringing focus back to the structural practices that manage quantity and creating a balance between the two so that you have effective and efficient systems,” Reed said.
Developers in those jurisdictions may see little change in stormwater requirements. On the other hand, he added, “some jurisdictions have not built a structural facility on any project in the last 10 years,” so new state regulations may trigger substantial change in those areas.
In addition, the current debate over stormwater regulations is focused on new construction. How and whether local jurisdictions apply them to redevelopments is also unresolved.