As the regional climate warms and storms become more frequent and intense, increases in pollutant runoff and harmful algal blooms threaten Dane County’s water resources and stormwater infrastructure. Regional water quality planning is crucial to protecting our lakes, rivers, streams, and groundwater and helping municipalities build climate resilience.
Dane County Climate
Long term trends in precipitation and temperature determine a region's climate, which in turn impact water quality by influencing water temperatures, stormwater runoff, water levels, flooding, sediment and nutrient inputs, and more. Dane County's climate is typical of the Great Lakes states, with long, cold, snowy winters and short, often humid summers. Most precipitation falls between April and September, peaking in June and bottoming out in January.
The ground usually begins to freeze at the end of November and thaws in mid-April. Severe storms often occur from late fall through mid-spring. The potential for runoff and severe erosion is typically highest in March and early April when heavy rainstorms and snowmelt occur on bare or sparsely covered ground.
Precipitation and Temperature Trends
Recent precipitation data shows wide variation from long-term averages (1981-2010), particularly in the summer months. Average temperatures in the last decade vary most widely from long-term averages in winter and early spring.
- Select each year to change the display
- Hover over the total annual precipitation to see how it compares to the long-term average
Climate Change
Climate change refers to long-term changes in the average weather patterns that have come to define our local, regional, and global climates. Human activities such as burning fossil fuels, agriculture, waste management, and deforestation release greenhouse gases like carbon dioxide, methane, and nitrous oxide. These gases act as a heat-trapping blanket in the Earth’s atmosphere, disrupting natural processes and altering weather patterns.
Even as we work to reduce greenhouse gas emissions, we have already committed to a certain degree of long-term warming based on past and current emissions. According to the Wisconsin Initiative on Climate Change Impacts (WICCI), this will mean warmer and wetter weather and more frequent extreme weather events for the Dane County region.
Since 1950, statewide temperatures have warmed about 3°F, and precipitation has increased by nearly 20 percent (about 5 additional inches each year). The last two decades have been the warmest on record, and the past decade has been the wettest. Winters are warming more rapidly than summers, resulting in fewer days with frozen conditions. These trends are expected to continue and potentially become more severe, impacting future weather patterns, flood risk, and water quality. By mid-century, Dane County’s climate will likely be more similar to the historic climate of south-central Illinois.
The reality of these impacts hit home in August 2018 with a major flooding event that resulted in loss of life and millions of dollars in damage. This event heightened regional awareness of the importance of increasing flood resilience and reducing future flood risk.
Climate and Water Quality
Temperature and precipitation directly impact water resources, meaning local water quality will inevitably be impacted by climate change. More rapid, intense rain events can generate increased surface runoff and cause localized and flash flooding. Winter ice cover and stream, groundwater, and lake levels are all influenced by climactic trends. Native biota are also adapted to the local climate; as changing conditions alter habitat conditions like water temperature, nonnative and nuisance species can prosper as native species struggle.
In order to protect aquatic habitats, manage stormwater runoff, and prevent increased pollutant loading, CARPC and its regional partners are incorporating climate mitigation and resilience measures into all water quality plans and initiatives.