Seal of Dane County County of Dane
Dane County Office of Energy & Climate Change

Flood Mitigation & Adaptation

Waunakee Park

Recent flooding has had a major impact on our communities and has resulted in millions of dollars of damage. Climate change is expected to bring more frequent severe storms and extreme temperatures, meaning such events will become more common.

A report by a Dane County technical work group looked at lake level conditions and modelled various scenarios to improve resiliency for future events. Currently, water comes into the Yahara Chain of Lakes faster than it goes out — taking two inches of rain over two weeks to leave the Yahara Lakes system. The group found that removal of sediment could lower flood risks by increasing water flow through the system. Harvesting aquatic plants has also proven to be a successful strategy, doubling the flow of water after the heavy rains of August, 2018.

An aquatic plant harvester at work in a Dane County waterway.

About 8.5 million pounds of sediment enters the Yahara system annually from urban runoff. In an effort to reduce the risk of future flood damage, Dane County has initiated a $2 million multi-phase project to reduce sediment at six key sites. The project will also improve fish and wildlife habitat in the Yahara lakes.

In 2019, two new aquatic plant harvesters were added to the fleet of 13 to remove aquatic plants, trees, and other large items of debris that restrict flow in the Yahara River. In addition to flood mitigation, aquatic plant removal can also cut down on the amount of phosphorus found in the Yahara Chain of Lakes, which can increase the frequency and extent of hazardous algae blooms.

We can anticipate the adverse effects of climate change. Dane County is taking action to prevent or minimise the damage they can cause. Well planned, early adaptation will save money and lives, making our community more resilient in the face of climate change.