With higher Great Lakes, review zoning for coastal resiliency: Part 2
Coastal hazards affecting public and private property change as weather, seasons, and climate change. With such a dynamic system, zoning regulations along the Great Lakes may need to be amended in order to protect property and Great Lakes access.
Beyond high risk erosion areas, storm surges, seiches, and large waves, covered in Part 1 of this two-part series, another important piece of information for decision makers is the 100-year base flood elevation (i.e. the extent of the Federal Emergency Management Administration’s (FEMA) Special Flood Hazard Area (SFHA)) along the jurisdiction’s Great Lakes shoreline. The State of Michigan requires that structures built in the SFHA be constructed at least one foot above the base flood elevation. However, this is a still water level and does not account for waves, storm surges, or seiches along the Great Lakes shoreline, although FEMA is currently conducting a Great Lakes Coastal Flood Study to update flood risk information for communities on the Great Lakes shoreline.
Information about lake levels, wave size, and flood elevations is helpful in determining the appropriate setback for construction and modification of occupied structures such as homes, garages, attached decks, etc. Another type of shoreline construction that is often regulated in local zoning ordinances is construction of erosion control structures such as seawalls and bulkheads.
From a strictly ecological perspective, construction of seawalls should be avoided in favor of other erosion control measures because hard surfaces reflect wave energy and increase erosion in the vicinity of the structure. However, there are circumstances where such structures are warranted, based on site conditions including wave energy, characteristics of the shoreline, rate of change of the shoreline, and the location of existing structures onsite and adjacent to the site, to name a few. Given the importance of local conditions in determining the appropriateness of erosion control structures, it may be best for zoning ordinance standards to discourage construction of seawalls by banning their construction except where warranted by a hydrological analysis and/or engineer’s findings. If the shore protection structure is constructed in the waters of the Great Lakes or lies below the OHWM, a permit must be obtained from the DEQ pursuant to Part 325 of the Natural Resources and Environmental Protection Act (Public Act 451 of 1994, as amended) being MCL 324.32501 et seq.
With all this technical information, what is a Great Lakes shoreline community to do? Given the dynamics of the coastal environment and the many factors to consider, it is probably best for a community to work with a licensed engineer if exploring changes to the current shoreline setback.
The City of St. Joseph, Michigan recently conducted a coastal engineering study to gain objective information about local shoreline changes and how best to amend zoning to protect private property from coastal hazards while protecting the public’s access to Lake Michigan under the public trust doctrine. Ultimately, the City of St. Joseph decided to adopt an overlay zoning district along a portion of the Lake Michigan shoreline that prohibits the construction of permanent structures. Essentially creating a ‘no build’ setback, the action is intended to maintain public access along the lake and prevent damage to private property during periods of high water and severe storms.
Michigan State University Extension conducts research and education about the Great Lakes shoreline as part of the national Sea Grant network and also educates communities about natural resource protection and planning and zoning with staff located throughout the state. For more information, find a Sea Grant and/or MSU Extension expert.