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Lancaster's Stormwater Rules Threaten Accessory Dwelling Unit Growth

  //house-home.news-articles.net/content/2026/01/0 .. les-threaten-accessory-dwelling-unit-growth.html
  Published in House and Home on Saturday, January 3rd 2026 at 9:05 GMT by LancasterOnline

Accessory Dwelling Unit Dreams Doused? Lancaster Stormwater Rules Could Stifle Growth

Lancaster City’s ambitious plans to encourage accessory dwelling units (ADUs), often called "granny flats" or carriage houses, are facing a significant hurdle: the city's stringent stormwater management regulations. A recent report in Lancaster Online highlights how these rules, designed to address flooding and water quality issues, may inadvertently create a barrier for homeowners hoping to build ADUs on their properties, potentially undermining the city’s broader goals of increasing housing density and affordability.

The article, part of the "Lancaster Watchdog" series, focuses on concerns raised by residents and developers alike about the practical implications of the stormwater requirements when applied to smaller residential lots – precisely the type of property where ADUs are most likely to be built. The city approved an ordinance in 2021 aimed at easing restrictions on ADUs, intending to allow for more flexible designs and encourage their construction. However, this ordinance has been largely stalled by the difficulty homeowners face in meeting the stormwater management standards.

The Stormwater Challenge: A Deep Dive

Lancaster’s stormwater regulations are among the strictest in Pennsylvania. They require developers – including homeowners building ADUs – to manage stormwater runoff on-site, preventing it from overwhelming existing infrastructure and contributing to flooding downstream. The city's goal is to mimic pre-development conditions, meaning that the rate and volume of water leaving a property after construction shouldn’t exceed what left before. This typically involves implementing techniques like rain gardens, permeable paving, or underground detention systems.

The problem arises because many Lancaster properties are small and densely built. Adding an ADU often means reducing existing green space – lawns, gardens, trees – which naturally absorb rainwater. The more impervious surface (roofs, driveways, patios) added, the more stormwater needs to be managed. Meeting these requirements on a tiny lot can be incredibly challenging and expensive.

"It’s essentially impossible for many homeowners to comply," stated Ryan Dummitt, a local developer interviewed in the article. He explained that he has had multiple projects stalled due to the inability to meet the stormwater regulations while also fitting an ADU onto the property. The cost of implementing compliant stormwater management systems can easily add thousands of dollars to the construction budget, making ADUs financially unfeasible for many homeowners, particularly those with limited resources.

Beyond Cost: Design Limitations & Bureaucratic Hurdles

It’s not just about money; the regulations also limit design options. Rain gardens and other green infrastructure solutions require space that may simply not be available on a small lot. Underground detention systems are expensive to install, particularly in areas with high water tables or difficult soil conditions. The article highlights instances where homeowners have been denied permits because their proposed stormwater management plans didn’t meet the city's requirements, despite attempts at innovative solutions.

Furthermore, navigating the permitting process itself has proven frustrating. Homeowners often encounter conflicting interpretations of the regulations and a lack of clear guidance from city officials regarding acceptable alternatives. The article points to a perceived disconnect between the intent of the ADU ordinance (to encourage density) and the practical application of the stormwater rules (which effectively discourage it).

A Call for Re-evaluation & Potential Solutions

The Lancaster Online report underscores a growing frustration within the community regarding the unintended consequences of the stringent stormwater regulations. Several potential solutions have been proposed, including:

• Relaxing Stormwater Requirements for ADUs: This could involve allowing exemptions or reduced requirements for smaller ADUs or those built on particularly constrained lots.
• Prioritizing Alternative Stormwater Management Techniques: Encouraging and incentivizing the use of innovative green infrastructure solutions that are more space-efficient and cost-effective, such as rain barrels or strategically placed permeable pavers. The city’s own website details various approved practices (see [ https://cityoflancasterpa.gov/departments/engineering/stormwater-management ]).
• Streamlining the Permitting Process: Providing clearer guidance and technical assistance to homeowners navigating the permitting process, reducing bureaucratic delays and inconsistencies.
• Considering Regional Solutions: Exploring opportunities for regional stormwater management infrastructure that could alleviate pressure on individual properties within the city limits. This aligns with broader discussions about addressing flooding issues across Lancaster County, as mentioned in related articles (e.g., [ https://lancasteronline.com/news/local/flood-control-projects-on-conestoga-river-face-funding-challenges/article_8c4b0a1f-7263-59d4-b6bc-9af682e1561b.html ]).

The Bigger Picture: Housing Affordability & Community Goals

The ADU issue is more than just a technical hurdle; it represents a broader challenge in balancing environmental protection with the need for increased housing affordability and density within Lancaster City. ADUs are seen as a valuable tool for addressing the city's housing shortage, providing opportunities for homeowners to generate income while creating much-needed rental units. The current stormwater regulations risk undermining these goals by effectively excluding many potential ADU builders from participating.

The Lancaster Watchdog report serves as a crucial reminder that well-intentioned policies can have unintended consequences and that ongoing evaluation and adaptation are essential for achieving desired outcomes. The city now faces the task of finding a way to reconcile its stormwater management objectives with its housing goals, ensuring that Lancaster remains a vibrant and affordable place to live for all residents.

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