© 2018-2019 Lake Denoon Lake District  Inc. - Muskego, WI, USA


Sonar Treatment

A whole-lake treatment with Sonar (Fluridone) is underway for 2019/2020.  This was determined by the LDAA and LDLD to be the best option for controlling the two most prominent invasive weed species Eurasian Water Milfoil and Curly Leaf Pondweed.   The project will consist of a primary application conducted in June 2019 with a booster application in mid summer and a potential spring 2020 booster. The selected vendor is  Marine Biochemists. The project is financed through a loan which will be repaid with normal LDLD special assessment revenues.  Financing has been secured through the Board of Commissioners of Public Lands (BCPL).  The DNR has approved our request and has issued our permit.  The initial product application was conducted on 6/3/19.  The treatment is working as expected with good control of EWM growth.  This is the first year in many where EWM is not growing above the water surface and getting shredded by boat props.  We need to continue maintaining the Sonar product in-lake level at or above 2 parts per billion (ppb) for as long as we can.  As called for in the plan, we've taken a series of residual measurements and the Sonar product levels have fallen below 2ppb so our vendor conducted booster applications on 8/14/19 & 11/4/19.  We'll take another sample this year and next spring in anticipation of a final boost application in May 2020.

Project Plan  |  DNR Fluridone Factsheet  | Project Files


A committee is being formed to review the SEWRPC Report's recommendations for managing our watershed.  Lake Denoon is unique in that it has a small watershed for its water volume.  Combined with its long retention time (average of 3.6 years), this means that the lake is sensitive to smaller amounts of incoming nutrient pollution.  The main goal of watershed management is to drive storm-water through plant buffers and underground where pollutant nutrients (phosphorus and nitrogen) are filtered and clean water enters the lake through its aquifer recharge system.  The objective of the new committee is to determine which of the SEWRPC recommendations are viable for the District to pursue. 


Please email watershed@ldld.org if you can donate some time and/or talent to this committee.