DNR Taking Input on Nitrogen Study until Jan. 13

The Department of Natural Resources hosted a webinar last month to discuss the results of a study examining nitrogen in the surface waters of the Northeast Lakeshore TMDL (total maximum daily load) study area. 

The nitrogen study evaluates the amounts of nitrogen introduced into surface waters relative to climate, land use and other watershed characteristics. It also evaluates potential methods of reducing the amounts of nitrogen introduced into surface waters within the study area, which spans a portion of the Lake Michigan watershed from just south of Sturgeon Bay to Port Washington, and reaches west toward Lake Winnebago.

A recording of the Nov. 9 webinar and the draft report for the nitrogen analysis are posted to the Northeast Lakeshore TMDL webpage at The DNR is inviting input on the report through Friday, Jan. 13. Input will be incorporated into the final report. 

The biggest contributor of nitrogen on the landscape within the study area, according to the draft report, is manure application, and commercial fertilizer is also a significant contributor. Both inputs are essential for the growth of plants and crops, but when too much nitrogen is applied, it can be exported to surface waters or groundwater and can have negative impacts on human health and aquatic health.

The nitrogen study is in addition to the TMDL study that is being conducted for total phosphorus and TSS/sediment.

The nitrogen study, unlike a TMDL, does not result in allocations or permit limits. The study is purely for informational purposes.

Under Act 59 in 2017, the Wisconsin Legislature adopted Wis. Stat. s. 281145, which outlined requirements for river and stream monitoring and a study of nutrients from point and nonpoint sources in the Northeast Lakeshore study area. This study took the form of a TMDL for total phosphorus and a separate watershed study for nitrogen.

Learn more about the Northeast Lakeshore TMDL at the Northeast Lakeshore TMDL webpage at, or contact Kevin Kirsch at [email protected] or Eric Hettler at [email protected].