Wisconsin's climate is changing. Wisconsin's cities and towns must also change how they manage their water resources if they are to adapt to the increases in rainfall and groundwater elevation we are already seeing. The Stormwater Working Group has brought together Wisconsin water resource managers to find ways to reduce risk to our communities and improve our stormwater management infrastructure.
Recent analysis of historical data, combined with climate model downscaling, suggest that the southern Wisconsin precipitation events of 2008 are part of a trend toward wetter conditions and more intense rainfall. Climate models also suggest that increased winter snow pack, and late winter rainfall, may result in high regional groundwater tables and lake levels, and saturated soil conditions.
Local and state government and private sector developers make significant investments in long-lived infrastructure that controls or is affected by stormwater runoff from large rainfalls. Likewise, municipal waste water treatment plant operators make substantial long-term investments in their system capacity that anticipates development, but not increased stormwater inflow and groundwater infiltration. This infrastructure is designed using standards based on rainfall data from the latter half of the 20th century. By having assumed“stationarity” of climate in the design of our infrastructure, we are now vulnerable to the following impacts from more intense rainfall events and elevated groundwater:
In summary, our previous investment in public safety and environmental protection risks being overwhelmed by precipitation impacts that are beyond those anticipated by past infrastructure designers and water resource managers.
While recent analysis of regional climate and rainfall data have provided insights into changes in climate over the last several decades, our ability to anticipate future conditions, and adopt appropriate adaptation strategies, will require more and better data about precipitation in Wisconsin. For example:
There is a growing consensus that scientific knowledge about the potential increase in magnitude and frequency of large rainfalls is sufficient to warrant immediate changes in the methods used to design and manage storm water-related infrastructure. For example, the following steps have been identified by the Stormwater working group:
Please contact Ken Potter or David Liebl if you have any comments or concerns regarding Wisconsin's stormwater and our changing climate or if you would like to have someone from the Stormwater Working Group make a presentation to your group or town.