Lake ice reporting program

The formation and break-up of ice are important milestones for a lake each year. Tracking the dates of their occurrence is important to understanding a lake’s seasonal cycles.

Lake ice

Ice is a hot topic! From Midwest lakes to Arctic glaciers, the presence and absence of ice is helping the world better understand the effects of global climate change. Minnesota's waters and winters are a great combination for gathering ice data needed to track climate change locally.

The Minnesota Pollution Control Agency (MPCA) began collecting lake ice data from volunteers in 2003 and is looking for more volunteers. The larger the data sets available to researchers, the better we can understand the effects changing ice cover has on lake health, local wildlife and recreation.

Join us: Become a lake ice reporter today

Send us an e-mail:

  • About you: Your name, address and phone number
  • About your lake: Name of the lake you are reporting for and the county it is located in. Please include the Lake ID number: Binary Data LakeFinder (Minnesota DNR). If the lake has a common name such as Long, Round or Deer, consider including other location identifiers like the nearest town or road.

Duties: What do reporters do?

Volunteer observers make it possible for ice data to be collected on hundreds of lakes in Minnesota.

  • Record ice-on and ice-off dates for your lake.
  • Submit data to MPCA by e-mail or postage-paid cards. Volunteer Water Monitors can include ice data in annual reporting using the volunteer water monitoring Secchi datasheet.

Guidance for reporters

Ice on

As fall turns to winter, it’s common for lakes to freeze, thaw, and refreeze. In light of this, there are often several ice-on dates each fall, depending upon the lake and local weather conditions. It’s important for us to know the last ice-on date for each season, but we are also interested in knowing when lakes freeze for at least 24 hours and then thaw again. There can be a lot of lake ice activity in the fall and we are interested in collecting all the data you are able to gather.

  • What if the lake develops a thin layer of ice overnight and then breaks up during the day – does this need to be recorded? If ice forms and thaws all in one day, feel free to ignore it. However, if the ice stays on for more than one day, then we would like to know about it.
  • How thick does the ice need to be to count as ice-on? If there is continuous ice cover across the lake, please record the date regardless of whether it is safe for walking or driving.
  • How can I tell if the whole lake is covered with ice? If you see vapors coming off the lake in dark areas, the lake is open there. If you can’t see the whole lake, you should invent your own rule for deciding if ice cover has occurred, write down the definition and send it to us when you send in your dates. For instance, your rule may be what you can see from your house. The important thing is to be consistent in your decision from year to year.

Ice off

As winter turns to spring, lake ice slowly begins to melt as the weather warms and days get longer. There is often less activity to record during ice-off, with most volunteers submitting one ice-off date each spring.

  • When can ice-off officially be declared for a lake? Ice-off is the date when the ice is essentially gone from the lake. If there is some ice pushed by the wind up on shore, but the water is essentially ice-free, then the ice is out. If you have your own definition, which may be necessary on bigger lakes, write it down and send it to us. Your definition may be the ability to navigate a boat from point A to point B, or ice-free as far as you can see from your house. The most important thing is to be consistent from year to year.
  • What if ice forms again after it completely breaks up? Normally, lakes do not refreeze in the spring once the ice has gone. However, if ice does form again, record the date of the formation and the following ice-off.

Access the data

Volunteer-collected ice data is stored at the MPCA and made available to anyone, by request, interested in using and studying it. We also share the data with the Minnesota State Climatology Office, based out of the Department of Natural Resources (DNR).

If you would prefer a spreadsheet of historical ice data for any lake in the state, please contact Shannon Martin at 651-757-2874 or 800-657-3864 toll free.

Contact us

For questions regarding the Lake Ice program at the MPCA, or to request data, please contact Shannon Martin at 651-757-2874 or 800-657-3864 toll free.