Mean endothall concentrations in 2013 water samples showed higher concentrations and longer exposure times in treatment target areas compared to samples collected in 2014 and 2015. Endothall concentrations in samples from 2014 were similar to concentrations in samples from 2015. Part of the difference between 2013 compared to 2014 and 2015 is explained by the higher application rate of 1.06 ug/L ae in 2013 compared to 0.71 ug/L ae in 2014 and 2015. The mean endothall concentration at 72 HAT was 469 ug/L ae compared to 44 ug/L ae in 2014 and 64 ug/L ae in 2015. Winds were from the south, southeast in 2013 and may have helped to hold herbicide in the target area resulting in longer exposure times (Figure 5). Winds were from the north northeast in 2014 and north, northwest in 2015 and may have helped to push endothall out of the treatment target area.

A progress summary report of the activities and results of those activities conducted in conjunction with the AIS Treatment Grant ACEI 133 13 for 2013 through 2015. This includes a summary of the herbicide treatments for the last three years and the associated results, including the native plant response to that treatment, and a discussion of the other grant related activities undertaken during this period.

Big Chetac Lake (WBIC 2113300) is a 1,920-acre stratified drainage lake in southwestern Sawyer County, Wisconsin in the Town of Edgewater (T37N R09W S19 NE NE). It reaches a maximum depth of 28ft in the narrows between the islands in the south basin and has an average depth of approximately 14ft (Busch et al. 1967). The lake is eutrophic (nutrient rich) in nature with summer Secchi readings averaging 3.3ft over the past 17 years (WDNR 2015). This poor to very poor water clarity produced a littoral zone that extended to approximately 12.5ft in the spring of 2015. The bottom substrate is predominately muck in the lake’s side bays and throughout the north and south ends, and a mixture of sand and rock along exposed shorelines, the mid-lake narrows, and around the islands (Busch et al. 1967).

Curly-leaf pondweed (Potamogeton crispus) Point-intercept and Bed Mapping Surveys, and Warm-Water Full Lake Point-intercept Plant Survey Big Chetac Lake –WBIC: 2113300, Sawyer County, Wisconsin

Big Chetac Lake (WBIC 2113300) is a 1,920-acre stratified drainage lake in southwestern Sawyer County, Wisconsin in the Town of Edgewater (T37N R09W S19 NE NE). It reaches a maximum depth of 28ft in the narrows between the islands in the south basin and has an average depth of approximately 14ft (Busch et al. 1967). The lake is eutrophic (nutrient rich) in nature with summer Secchi readings averaging 3.3ft over the past 17 years (WDNR 2015). This poor to very poor water clarity produced a littoral zone that extended to approximately 12.5ft in the spring of 2015. The bottom substrate is predominately muck in the lake’s side bays and throughout the north and south ends, and a mixture of sand and rock along exposed shorelines, the mid-lake narrows, and around the islands (Busch et al. 1967).

Draft: Big Chetec Lake, Sawyer and Barron Counties (WBIC 213300), Dipotassium Salt of Endothall Herbicided Concentration Monitoring Summary, 2014

Final Big Chetac Fact Sheet 2014

CLP post treatment survey Big Chetac 2014

Lake Chetac 2013 CLP Herbicide Treatment Results and FAQ

CLP Pre and post treatment surveys

GIS maps and data of monitored areas

Management/ treatment summaries

Aquatic Plant and Turion Monitoring Results