Aquatic Vegetation and Management Study

Why doesn’t the PRRD just clean up the lake?

Water, lakes, rivers, streams, aquatic animals, etc. within British Columbia are the jurisdiction of the Province of BC and in some instances also the Government of Canada. The Province of BC has laws that protect water resources in the province by restricting and regulating certain activities that are conducted on, near or within bodies of water. The PRRD has to follow these laws the same as any individual or other organization and is required to apply for permits to conduct any regulated activities, like removing aquatic vegetation. 

What about areas around private docks and weeds on the shorelines?

At this time, the scope of the Aquatic Vegetation Management Study is to identify possible areas (if any) that could benefit from the removal of aquatic vegetation with the least environmental harm.  Possible treatment areas will aim to provide the greatest benefits (recreational, safety, etc.) to the public with the least impact. Shoreline vegetation removal is not being studied within the scope of the PRRD’s Aquatic Vegetation Management Study. Any works conducted in and about a watercourse in BC requires Provincial approval.  That legislation also pertains to private landowners where their properties include watercourses or border watercourses.

Why conduct aquatic harvesting?

To improve recreational opportunities by creating access to areas of the lake where vegetation is less dense, to create open areas that improve angler access to sport fish and to open shoreline areas for activities such as swimming and paddle boarding. Selective removal of excess aquatic vegetation can be considered a safety improvement as it decreases the potential for clogging boat motors and reduces hazards to swimmers. Additionally, selective harvesting of aquatic vegetation can increase aesthetic value for lake users, improve dissolved oxygen levels in the winter (which can lead to fish kills) by reducing the amount of decaying vegetation and remove some of the excess nutrients temporarily bound in the aquatic vegetation that contribute to algal blooms.

What is the ecological importance of aquatic vegetation?

Aquatic vegetation is an important and naturally occurring part of the lake ecosystems. Aquatic vegetation produces oxygen while it grows, stabilizes sediments, can reduce erosion and provides important habitat for fish and invertebrates.

Do invasive aquatic plants occur in these lakes?

NO! Surveys conducted by local groups such as the Charlie Lake Ecological Society, the Swan Lake Enhancement Society and the One Island Lake Cabin Owners indicate that all the aquatic vegetation present in these lakes are naturally occurring species. These lakes are naturally eutrophic, meaning the lakes are highly productive with an abundance of naturally occurring aquatic vegetation.

Will harvesting aquatic vegetation reduce the growth of blue-green algae (cyanobacteria)?

It is unlikely that the small area targeted by harvesting (likely less than 2% of the lake surface area) will have a significant effect on blue-green algae concentrations. Blue-green algae blooms are typically caused by excessive nutrient inputs, mainly nitrogen and phosphorus. The primary inputs promoting these algal blooms are agricultural and stormwater runoff and leaching from septic systems. Addressing these inputs is beyond the scope of this current program. However, aquatic vegetation also requires phosphorus and nitrogen, so harvesting aquatic vegetation, coupled with appropriate disposal will remove some of the excess nutrients that enter the lake.

What fish are in the lakes and how will this affect them?

The fish biodiversity of these lakes has been altered substantially from their original species composition, and in fact, most of the fish in Charlie, Swan and One Island Lake are introduced. For a more detailed profile, click here. While aquatic vegetation provides important habitat for fish and invertebrates, temporarily removing a very small amount (<2%) of aquatic vegetation during the summer months is not expected to have a significant impact to the current fish populations. Additionally, excessive aquatic vegetation reduces dissolved oxygen levels during the winter which can lead to fish kills; removal of some aquatic vegetation could help maintain dissolved oxygen at improved levels during winter months.

Has harvesting aquatic vegetation ever been tried in the Peace region?

YES! A pilot program was conducted by the Ministry of Environment at Swan Lake in 1987 using a harvester from Vernon, BC. This program harvested aquatic vegetation from four hectares of Swan Lake and concluded that mechanical harvesting can be an effective, but temporary, means of controlling unwanted aquatic vegetation at Swan Lake. This program suggested that a single harvest in the early summer should provide appropriate conditions for recreation in the summer months.

How fast will the aquatic vegetation regrow?

It is important to note that aquatic harvesters do not eliminate aquatic vegetation; like a lawn mower, they simply cut it below the surface where it will not be a nuisance. More than one cut per year may be required to maintain aquatic vegetation at a desired level. Studies conducted further south suggest that harvesting aquatic vegetation to a depth of approximately 1.5 m in mid to late June will take less than 30 days to regrow to pre-harvest levels. A second harvesting event in late July to early August would take longer to regrow and would likely maintain reduced levels of aquatic vegetation until mid-September to October. A pilot study conducted at Swan Lake in 1989 suggested that a single cut in early summer would be sufficient to keep vegetation below nuisance level for most of the summer. Should this program proceed, it is likely that a single harvesting session will occur at the beginning and the need for additional harvesting would be determined based on the initial results and budget considerations.

How much of the lake would be affected?

We are currently seeking public opinion on target areas. However, vegetation harvesting would likely occur in high-use areas such as boat launches and potential swimming areas. Overall, this would be a very small (likely less than 2%) portion of the lake area. The 1987 pilot program at Swan Lake targeted four hectares which is less than 1% of the surface area at Swan Lake.

How do you remove the vegetation from the lake and get it to shore?

Typical harvesters have a capacity less than 15 cubic metres. When operating on large waterbodies, a transport barge is often used to efficiently transport vegetation from the harvester to an onshore conveyor which puts the vegetation into a dump truck for composting or disposal.

How will the harvested vegetation be disposed of?

Ideally, the harvested vegetation will be used for composting and / or ground cover in gardens to provide nutrients and reduce water loss. This could include making harvested vegetation available to local landowners. There could also be an opportunity for a commercial composting service or disposal at PRRD landfills if needed. Note that most of the mass of aquatic vegetation is water; the harvested aquatic vegetation will shrink substantially as it dries out.

Will landowners have an option for aquatic vegetation removal around docks and shorelines?

At this time, it is unlikely that the program will accommodate areas around private residences. However, should public support exist, the feasibility of such a program could be investigated.

Will this cost me more in taxes?

If a permit to remove aquatic vegetation from Swan Lake, Charlie Lake and One Island Lake is approved, the PRRD would have to conduct a referendum which would determine support from eligible voters for the service. The bylaw would outline the purpose of the service, how the service would be payed for and a service area (who would pay for the service). If the referendum were to pass, taxpayers in the approved service area would pay taxes. Taxes would cover the full cost of delivering the service including operating and maintenance of the equipment, administration, insurance expenses, etc.  

Charlie Lake

Native fish species have historically included: white sucker, brook stickleback, northern pearl dace, and northern redbelly dace. However, apart from white sucker, none of these species have been detected recently suggesting they are no longer present in the lake or are present in small numbers.

Sportfishing for walleye and pike are popular activities; however, these species are not naturally occurring in Charlie Lake. They were introduced in the 1950s. Yellow perch were introduced from Swan Lake in 1981. Introductions of rainbow trout failed in 1933, 1947, and 1949 as did an attempt to stock largemouth bass in 1962. In 1986, several species of forage fish (minnows), including burbot, were transplanted from Alberta when sampling efforts failed to find previously existing native forage fish species.

Swan Lake

Yellow perch were introduced to Swan Lake in the 1970’s following recommendations of regional fish biologists. Walleye do not occur naturally in Swan Lake; they were introduced from Charlie Lake in 1984. Walleye in Charlie Lake were introduced in the 1950s. Northern pike are likely naturally occurring in Swan Lake; they were present in large numbers in the 1970s and no records of stocking pike were found. 

One Island Lake

One Island Lake provides a unique trophy brook and rainbow trout fishing opportunity for Peace Region residents; however, neither of these are native species. One Island Lake has been stocked with brook and rainbow trout since 1955. Minnow species in One Island Lake include fathead Minnow, finescale dace, and brook stickleback.