In 2006, the Wisconsin Department of Natural Resources identified the presence of Hybrid water milfoil (HWM) – a cross between Northern and Eurasian water milfoils (Myriophyllum sibiricum X Myriophyllum spicatum) in the lake. Because of this finding, the Horseshoe Lake Improvement Association commissioned an exotic species rapid assessment point intercept survey in June 2007 to determine the distribution and density of HWM. In 2008, two full point/intercept surveys and a fall bed mapping survey of HWM were requested to provide the baseline data needed to develop an Aquatic Plant Management Plan (APMP) for the lake. This survey is a follow up to the 2008 Bed Mapping Survey. The goals of the survey were to provide an estimate of total HWM acreage on the lake, to determine the effectiveness of 2009 control methods and to assist in developing control strategies for 2010.

In 2008, the WDNR and the Horseshoe Lake Improvement Association commissioned a cold-water exotic species survey, systematic point/intercept macrophyte survey, and fall Hybrid water milfoil bed mapping survey in preparation for developing an Aquatic Plant Management Plan for the lake. The full point intercept survey found macrophytes at 325 of the 515 total survey sites. We identified a total of 51 native plant species including five Wisconsin Special Concern Species (Spiny hornwort, Robbins spikerush, Farwell’s water milfoil, Filament-leaf pondweed, and Vasey’s pondweed) in and directly adjacent to the lake.

Horseshoe Lake (WBIC 2630100) is a 398 acre, mesotrophic, stratified, seepage lake located on the border of Polk and Barron Counties in northwest Wisconsin. In 2006, the Wisconsin Department of Natural Resources identified the presence of Hybrid water milfoil – a cross between Northern and Eurasian water milfoils (Myriophyllum sibiricum X Myriophyllum spicatum) in the lake. Because of this finding, the Horseshoe Lake Improvement Association commissioned an exotic species point intercept survey to determine the extent of infestation in the lake in preparation for the possibility of applying for a rapid response grant.

AIRR-029-08Horseshoe Lake Improvement Assoc., Rapid Response Program

19294306

AIRR-029-08