Floodplain Management

Floodplain management ordinances are a critical tool for local governments to reduce flood risk, protect public safety, and ensure community resilience. The primary framework for these regulations in the United States is the National Flood Insurance Program (NFIP), administered by the Federal Emergency Management Agency (FEMA). To participate in the NFIP, a community must adopt and enforce a floodplain management ordinance that meets or exceeds minimum federal standards. These ordinances regulate development within the Special Flood Hazard Area (SFHA), which is the land area that would be inundated by a flood having a 1-percent chance of being equaled or exceeded in any given year, also known as the 100-year floodplain.

Core components of an NFIP-compliant ordinance include requiring permits for all development in the SFHA, ensuring new and substantially improved residential structures have their lowest floor elevated to or above the Base Flood Elevation (BFE), and preventing encroachments in the regulatory floodway that would result in any increase in flood levels. While the NFIP provides the foundation for reducing flood damage, many communities adopt higher standards or complementary regulations to protect the broader functions of river corridors and shorelands. The model ordinance from Buffalo, Minnesota, provides an excellent example of a Shoreland Management Overlay District, which integrates flood damage reduction with water quality protection, habitat conservation, and aesthetic considerations for lands adjacent to lakes and streams. It serves as a useful supplement to a base floodplain ordinance, offering a more holistic approach to watershed management.

This model demonstrates how a community can use a tiered classification system to apply tailored standards to different types of waterbodies based on their ecological sensitivity and existing development patterns. It combines elements of zoning, land use controls, and performance standards to manage development impacts. While this example is based on a Minnesota state framework, its principles can be adapted by municipalities nationwide looking to enhance their existing floodplain regulations. For other related regulations, see the Model Ordinances library.

Key provisions

The Shoreland Management Overlay District ordinance establishes a set of land use controls that apply to lands near classified public waters. Its provisions are layered on top of the underlying base zoning for a given property.

Applicability and Jurisdiction

The ordinance applies to shoreland areas, defined as land located within specific distances of public waters. The jurisdictional area is 1,000 feet from the ordinary high water level (OHWL) of a lake, pond, or flowage, and 300 feet from a river or stream, or the landward extent of the designated floodplain, whichever is greater. This dual definition ensures that both riverine flooding and lakefront protection goals are met.

Shoreland Classification and Use Districts

A key feature of the model is its classification of waterbodies, which allows for standards to be tailored to the resource. Lakes are classified into three tiers:

• Natural Environment Lakes: Small, sensitive lakes with limited capacity for development.
• Recreational Development Lakes: Medium-sized lakes with moderate existing development and capacity for more.
• General Development Lakes: Large lakes or those with high levels of existing development.

Rivers and streams are classified as “Tributary.” These classifications, which must be delineated on the official zoning map, determine the specific lot size, setback, and other dimensional standards that apply within the overlay district.

Lot, Setback, and Height Standards

The ordinance establishes detailed dimensional requirements for new lots and structures to minimize impacts on public waters. Lot area and width standards vary significantly based on the waterbody classification and whether the lot is served by a public sewer system. For example, a single-family riparian lot on a Natural Environment lake without sewer service requires 80,000 square feet and 200 feet of width, whereas a similar lot on a General Development lake with sewer service requires only 15,000 square feet and 85 feet of width.

Structural setbacks are measured from the OHWL and from other features like bluffs. These setbacks are fundamental to providing a buffer that protects water quality, preserves habitat, and reduces property risk. The ordinance also requires that the lowest floor of a structure, including the basement, be placed at least three feet above the highest known water level or the OHWL, whichever is higher, providing a margin of safety known as freeboard. All residential structures are limited to a height of 25 feet.

Additional setbacks are required from the top of bluffs (30 feet) and public rights-of-way.

Shoreland Alterations and Performance Standards

The ordinance regulates activities that alter the landscape to control erosion and protect natural features. Intensive vegetation clearing is prohibited within shore and bluff impact zones and on steep slopes. Limited clearing is allowed to provide views and access, provided that screening of structures from the water is not substantially reduced. A grading and filling permit is required for moving more than 10 cubic yards of material on steep slopes or within shore/bluff impact zones, and for moving more than 50 cubic yards elsewhere.

Stormwater management is a key component, with a requirement that impervious surface coverage not exceed 25 percent of the lot area. The ordinance prioritizes the use of natural drainageways and vegetated surfaces to manage runoff, consistent with modern Stormwater Management principles. When constructed facilities are necessary, they must be designed to filter or settle suspended solids before discharge.

Administration and Permitting

A permit, administered by the Zoning Administrator, is required for construction of buildings, installation of sewage systems, and regulated grading and filling activities. The ordinance outlines a standard process for considering variances, which may not be granted if they circumvent the general purpose and intent of the ordinance. For certain actions like variances and conditional uses, the municipality must notify the state Department of Natural Resources, ensuring a level of state oversight.

Enforcement and Penalties

The City is responsible for administration and enforcement. The ordinance states that it is unlawful to violate any provision and that such violations are punishable according to the city code. This clear assignment of authority is essential for effective implementation.

Selected provisions, annotated

Structures must be placed in accordance with any floodplain regulations applicable to the site. Where these controls do not exist, the elevation to which the lowest floor, including basement, is placed or floodproofed must be at a level at least three (3) feet above the highest known water level, or three (3) feet above the ordinary high water level, whichever is higher.

Shoreland Management Overlay District, Buffalo, MN

This provision establishes a freeboard requirement, a best practice in floodplain management. By requiring the lowest floor to be elevated three feet above the known high water mark, the ordinance provides a factor of safety against floods that exceed predicted levels, wave action, and uncertainties in elevation data.

In shore and bluff impact zones and on steep slopes, limited clearing of trees and shrubs and cutting, pruning, and trimming of trees is allowed to provide a view to the water… provided that: The screening of structures, vehicles, or other facilities as viewed from the water, assuming summer leaf-on conditions, is not substantially reduced…

Shoreland Management Overlay District, Buffalo, MN

This performance-based standard for vegetation management balances homeowner desires with public resource protection. Instead of prohibiting all clearing, it allows for selective maintenance while preserving the natural aesthetic of the shoreline and the ecological functions of the vegetative buffer, a key principle of Stream Buffers.

Impervious surface coverage of lots must not exceed 25 percent of the lot area.

Shoreland Management Overlay District, Buffalo, MN

This simple, clear, and enforceable rule is a powerful tool for managing stormwater runoff at the site level. Capping impervious surfaces helps reduce the volume and velocity of runoff, promote infiltration, and protect water quality by limiting the transport of pollutants from the developed landscape into the adjacent waterbody.

Structures and accessory facilities, except stairways and landings, must not be placed within bluff impact zones.

Shoreland Management Overlay District, Buffalo, MN

This provision addresses the geotechnical hazards associated with development near steep slopes. By prohibiting structures in the bluff impact zone, the ordinance protects the stability of the bluff, prevents erosion, and reduces the risk of property damage from slope failure, a hazard distinct from but often related to riverine and coastal flooding.

What makes it a useful model

This ordinance serves as a strong model because it effectively integrates multiple community goals into a single, coherent regulatory framework. It moves beyond the single objective of flood damage reduction to also address water quality, habitat, and aesthetic values. This comprehensive approach is more efficient to administer and more effective at protecting the full range of functions and services provided by shorelands and floodplains.

The tiered classification system is a particularly valuable feature. It allows a community to apply the most protective standards to its most sensitive or undeveloped waterbodies while providing more flexibility in areas that are already heavily developed. This context-sensitive approach is more defensible and can achieve greater environmental protection with less impact on development potential than a one-size-fits-all regulation. It provides a clear roadmap for communities seeking to link land use regulations directly to the specific characteristics of their water resources.

Finally, the ordinance’s use of clear, quantitative standards (e.g., setback distances in feet, impervious cover in percent) makes it highly practical. These objective criteria are straightforward for applicants to understand and for staff to administer and enforce, reducing ambiguity and the potential for arbitrary decisions. It combines these prescriptive standards with flexible performance standards for issues like vegetation clearing, creating a robust and balanced regulatory tool.

Adaptation checklist for municipalities

Municipalities seeking to adapt this model should consider the following steps to tailor it to local conditions and legal frameworks:

• Confirm the legal authority to adopt a shoreland or floodplain overlay district under state enabling statutes.
• Inventory and classify all public waters within the jurisdiction according to local ecological conditions, development patterns, and community goals.
• Create or amend the official zoning map to clearly delineate the boundaries of the shoreland overlay district and the classifications of each waterbody.
• Establish a clear, legally defensible definition for the “ordinary high water level” (OHWL) or other reference mark, consulting state agency guidance where available.
• Customize the tables for lot area, width, setbacks, and impervious cover to reflect local environmental conditions and development objectives.
• Ensure that minimum elevation and floodproofing requirements are consistent with or more stringent than those required by the NFIP, referencing official FEMA Flood Insurance Rate Maps (FIRMs) and Base Flood Elevations (BFEs).
• Define “steep slopes” and “bluff impact zones” based on local soil types and topography, and develop specific standards for these areas.
• Designate a local official or department (e.g., Zoning Administrator, Planning Department) responsible for administration and enforcement.
• Identify the appropriate state or regional agencies that must be notified of certain permit applications, variances, or amendments.
• Integrate the ordinance with other relevant local codes, including subdivision regulations, building codes, and existing stormwater management ordinances.
• Develop a clear permit application form, review procedure, and schedule of fees.
• Establish penalties for non-compliance that are consistent with the municipality’s general enforcement authority.