Climate change impacts

In the city of Ann Arbor in southeastern Michigan, through which the Huron River runs, an increase in average precipitation and of extreme storm events pose a serious threat to health and the living environment. The Huron River supplies 85% of drinking water for Ann Arbor. When it rains, almost 100% of the urban rainwater flows into the Huron River. Pollution from runoff water lowers the quality of the domestic water supply and adversely affects downstream water and wetland ecosystems. Annual average precipitation in Ann Arbor has increased by 25% over the past 60 years, increasing the need for rainwater management to maintain a healthy river system.

Adaptation activity

The property rates structure in Ann Arbor was changed in 2006 to consider treatment of runoff and encourage more ecological rainwater management by property owners. The revised rates schedule was set based on impermeable surface areas, such as rooves, paved roads, sidewalks, courtyards, gravel, and stone paving. Through this initiative, more than $5 million in funds are provided each year for rainwater system management, maintaining water quality, rainwater education, the development of environmental regulations and nature conservation projects, and green infrastructure projects to reduce the burden on rainwater management systems. Owners of both commercial and residential properties are eligible for discounted rates if they adopt measures to reduce runoff rainwater (see figure).
In addition to these economic incentives, Ann Arbor is working with the Great Lakes Integrated Sciences + Assessments (GLISA) program. This collaboration helps to build community support for climate change initiatives and promote education on climate change and its impacts.

Outputs / Expected benefits

Educational programs that contribute to deepening public understanding of the relationship between rainfall and water quality are considered an important step in solving rainwater issues. It is also expected that the benefits of rainwater management initiatives will be spread by word of mouth.

Examples of building alterations that qualify for the discounted rates schedule (from left to right: rain garden, drywell, and water storage tank)
(Source: City of Ann Arbor "Stormwater")