Lake Weeds in Chestermere Lake

Over several decades the problem of lake weeds has worsened with the accumulation of sediments that used to flow into the lake from Calgary via the south canal. 

One consequence of years of sediment deposit means the lake has become much shallower than it used to be (35 feet of depth has become 11 feet in some areas). This allows the weeds to receive a lot more sunlight than they used to and they can grow right to and across the water’s surface in many areas. Since the Shepard Wetlands have been completed, there should be a significant reduction in sediment deposition in Chestermere Lake, and recovering some of the lost depth might now be possible. 

 

The bulk of the floating weeds are a result of the cutting done by the weed harvesters, and some are from boat propellers. They then float in to the shoreline depending on the wind direction. Lakefront owners spend countless hours each week collecting cut weeds that have floated in to their shorelines. These have to be loaded into City supplied large green bins and hauled to the roadside for pick up by City trucks. Many residents are not physically able to do this, or are working or away, and not able to gather them in a time sensitive manner. The task of lifting these wet heavy weeds has caused physical injuries to lakefront owners and we all agree we need a better solution. If left and not gathered, these weeds rot and cause bacteria and stench, so the job has to be done in order to preserve the quality of the lake water. More than 200 Tonnes of lake weeds are pulled from the water by owners each year, and the CLFOA continues to advocate for lakeside versus curbside weed pickup. The City is working on solutions with the CLFOA to accommodate this. The long-term goal is to eliminate the weeds or significantly reduce the weed growth, using dredging and scraping methods.

 

In the short term, there are some techniques to implement, test, and adopt. Weed removal can be improved in a variety of ways by putting City staff in the water, utilizing floating rafts, and adding skimmers and small barges to gather weeds. Daily visits to known hot spots using city staff to control the buildup of floating weeds will help to alleviate the burden that has been put on individual lakefront owners. The city is also considering setting patterns for harvesters to cut in rows using 3 machines. GPS installed and used on the harvesters could improve the present random cutting and accommodate for wind drift and waves. Staggering the harvesters is an option to reduce the number of floating weeds and it has also been suggested that if the skimmer had collector arms and an outboard motor it could become a fast and maneuverable tool for smaller week pickups. Weeds are a constant issue for CLFOA members, and while working in collaboration with the City of Chestermere, we are able to continue to make improvements and strive to manage the issue each summer. Each year lakefront owners continue to push for lake dredging as the long-term solution. Several attempts to execute dredging projects have failed, but we are seeing progress, and continue to advocate and lobby with all stakeholders for this very important and necessary solution.

City of Chestermere Statistics:

On average, summer students spend about 2,040 hours in total on the harvesting program. This results in regularly removing over 200 trailer loads of lake weeds, ultimately being converted into compost material.

A breakdown of weed harvesting volumes from 2018 – 2020:

2018:   215 trailer loads, 342 Tonnes

2019:  238 trailer loads, 378 Tonnes

2020:  202 trailer loads, 321 Tonnes


Alberta Aquatic Invasive Species Program – Flowering Rush, Nicole Kimmel (Presented at CLFOA Oct 2023 AGM)