Flood and Erosion Risk on Iosco County's Lake Huron Shoreline

Why Iosco County shoreline land plays by different rules

Iosco County's eastern edge runs along Lake Huron, including Tawas Bay and the sand spit at Tawas Point. Michigan first designated High Risk Erosion Areas (HREAs) along this kind of vulnerable Great Lakes shoreline back in 1986, under what's now Part 323 of the Natural Resources and Environmental Protection Act, and Iosco County's stretch was among the areas designated. EGLE revisited the county specifically in a 2023-2024 shoreline recession-rate study, updating the erosion rates first measured in the 1980s -- and found continued, real erosion, with some stretches of shoreline receding at an average of a foot or more per year and isolated areas measured at roughly 2.5 feet per year, with lingering damage from the high-water period around 2020 still visible in shoreline structures and interdunal wetlands.

That's not an abstract statistic for a land buyer. EGLE's own reporting noted permit requests for shoreline armoring (seawalls, riprap, and similar structures) in Iosco County jumped nearly 57% in 2020 over the prior year -- a direct sign of property owners reacting to real, ongoing land loss, not a theoretical risk.

The Erosion Hazard Line: a different setback than you're probably expecting

Most Michigan waterfront setback questions get measured from the Ordinary High Water Mark. Inside a designated High Risk Erosion Area, they don't. EGLE instead draws an Erosion Hazard Line for the specific stretch of shoreline, and every parcel in that HREA gets two setback distances measured from that line: a 30-year setback and a 60-year setback, calculated from the area's documented recession rate. A permit from EGLE -- not just the local building department -- is required before constructing any roofed structure or installing a septic system within the High Risk Erosion Area, regardless of what the county or township zoning ordinance otherwise allows.

In practice, this means a septic system replacement on an existing Iosco County shoreline home can trigger the same EGLE review as a new house, if the parcel falls inside the mapped HREA -- something a buyer focused only on the county health department's septic permit could easily miss.

The permit process and timeline

Once an HREA permit application reaches EGLE, it goes through a 30-day administrative completeness review before the substantive review period even starts; EGLE staff also visit the site to confirm the proposed structure's actual location relative to the shoreline and the Erosion Hazard Line. After the application is deemed complete, EGLE has up to 60 days to process it. Budget for that combined window -- up to roughly three months from a complete submission to a decision -- when timing a purchase around a planned building project on Iosco County shoreline land.

Before making an offer on a specific Lake Huron-frontage parcel in Iosco County, check it against EGLE's High Risk Erosion Area maps and the MiEnviro Site Map Explorer tool, which layers HREA boundaries and setback lines over parcel data. That step tells you whether the setback lines leave a realistic building envelope on the specific lot at all -- on a narrow or already-eroded parcel, the 30-year and 60-year lines can eliminate more buildable area than a buyer expects from the lot's platted dimensions alone.

What this means if you're buying

For an existing home on HREA-designated shoreline, ask directly whether the structure was permitted under HREA rules and whether it's now legally nonconforming relative to the current Erosion Hazard Line -- a nonconforming structure can usually stay as-is but may face real limits on expansion or reconstruction after storm damage. For raw or vacant shoreline land, get the parcel's specific 30-year and 60-year setback distances from EGLE before assuming a house of any particular size or location will fit, and budget the EGLE permit timeline into your construction schedule on top of whatever the county health department and township zoning otherwise require.