Water Withdrawal Assessment Tool can help local planning officials plan for the future: Part 2

Michigan’s web-based Water Withdrawal Assessment tool provides valuable information that planners can use to prevent water availability issues.

Editor's Note: View Part 1 of this article, which described water availability issues and the history of the Water Withdrawal Assessment tool.

Even in the midst of plentiful supplies, parts of Michigan are or will soon be facing increasing competition for water, especially groundwater, making it harder to extract those resources without impacting other users and the environment.

The web-based Michigan Water Withdrawal Assessment Tool is one resource local planners can use to assess their current situation and future vulnerability. The system keeps track of large-quantity water withdrawals and predicts the level at which cumulative withdrawal rates may cause an Adverse Resource Impact (ARI).

Planning officials can use the tool to identify the regulatory watersheds in their jurisdiction, then access the tool’s database to determine how close current water use in those watersheds is to the ARI level. Armed with that information, planning officials can develop plans that can help avoid future water availability issues.

One specific approach is to evaluate a community’s master plan future land use map and the zoning ordinance to identify areas currently planned for residential, commercial or industrial uses where access to municipal water supplies is not anticipated. Using the Water Withdrawal Assessment Tool’s maps, they can determine which watersheds those areas fall within.  At that point, planners can see on the tool’s database how close each watershed is to the ARI level and the amount of available water before that limit will be reached.

Planners can then compute the potential impact of future development.  Standard three-bedroom residences, for example, typically require a 20 gallons per minute (gpm) water supply, but may need up to 60 gpm if lawn irrigation is planned.  The cumulative effect in small subdivision could be 300 gpm or more. Even though residential well withdrawals are not regulated by state law, the impact could be as great as or greater than regulated large-quantity withdrawals. If high-risk watersheds are identified with this analysis, communities can amend its master plan and zoning ordinance to refocus growth toward less vulnerable areas. Economic development specialists could also use this information to compare client needs to available water supplies.

Another way that communities can reduce risk is to amend the site plan review process to require submission of the applicable large-quantity withdrawal registration prior to site plan approval.  This step helps ensure that these water-intensive uses comply with the state’s registration requirement.

Michigan has excellent water availability and low risk to stream and river ecology in most areas.  The greatest vulnerability is in areas with expanding agricultural irrigation in the southern Lower Peninsula especially in the southwestern region of the state.

The Michigan Water Withdrawal Assessment Tool website includes additional information about the tool, its history and instructions for downloading data. Visit the Michigan State University Extension website for additional information on water-related topics.

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