Help: Understanding how water limits housing development in Michigan
Sam from Michigan posted a great question in the Strong Towns Slack
I could really use some advice. I'm trying to calculate how many acres of land can be developed into housing, but to do that, I need to understand how water limits housing development in Michigan, and I've heard different things from different people. I know that it is difficult or illegal to build over some protected areas, and I know that flood insurance is very costly in floodplains. But, I don't know more details about how specific decisions are being made.
In the example (chosen at random!), I've overlaid the FEMA Floodplain Map (Red), the National Wetland Inventory (Blue), and the Michigan EGLE State Wetland Inventory (Yellow).
Would anyone who works in housing development, or wetland management, or just a knowledgeable resident, be able to shed some light on how this data could be used to determine if housing could be built in a given area?
Any thoughts or comments?
Comments
1 comment
This is a really good question and an exercise that communities should be doing as part of their long range or comprehensive plan. This type of mapping answers two questions: First, where are the places that we should build because they are not vulnerable to environmental or climatic events. Second, where are the places we seek to preserve or protect because of rare or unique habitats.
Alachua County Florida, has spent many years mapping and debating these boundaries. As a result they have adopted growth management policies and developed mapping to define the parts of the county that as a community they want to preserve.
https://growth-management.alachuacounty.us/CompPlan/Conservation
FEMA Floodplains, the National Wetland Inventory, and the Michigan EGLE State Wetland Inventory, are less than ideal locations for human habitat. These are locations prone to flooding and where there may also be rare and unique species of plants and animals. Development in these areas would require additional scrutiny and review compared to other places on the map.
Specific to Flood Plains, FEMA has established additional building standards and rules to offset the risk for flooding and property owners with insurance or a mortgage are required to have additional flood insurance coverage. It costs more to build in these areas. These rules also apply to the construction of infrastructure like water and sewer that must be hardened and protected from flood events, making the cost to maintain infrastructure more expensive.
Alachua County has worked for many years to remove or reduce the ability to develop in these areas. The struggle with these maps is confirming and validating the mapping. In your example, we can see perfect rectangles, a shape not naturally found in nature. I suspect that there is some language on these source files that say that these are not exact and would require confirmation with a land survey.
To respond to your question more directly, these highlighted areas may not be ideal for new development and may need to be removed from the overall development footprint of this community.
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