The town of Killarney, in southwestern Manitoba, has the good fortune to be situated on a beautiful lake, making it a popular destination for tourism and leisure. Cottages, permanent residences, campgrounds, parks and trees line the lake’s shore, creating unique opportunities for the town to attract visitors and new residents alike.

Unfortunately for the community, the lake undergoes an annual transformation from a clear blue to a sickly green due to invasions of cyanobacteria, or blue-green algae. This metamorphosis inevitably results in a loss of recreational value and affects the overall health of the lake. A lot of attention has been drawn to the massive problem of nutrient loading in Lake Winnipeg over the past few years, but this crisis runs deeper than just the province’s largest body of water: smaller lakes and waterways are also being affected.

The story of Killarney Lake is an important one because lessons from the past are informing the actions of today. Core samples taken from the lakebed have revealed heavy algae blooms are a notable part of the lake’s geological history, dating back at least 3,000 years. The town of Killarney was settled in the late 19th century, and as the population grew, so did the economic importance of the lake.

Recognition of this value in the mid-20th century influenced the town to employ various algae control methods, the most significant of which was the addition of “bluestone” or copper sulfate to the lake. Copper sulfate kills algae and reduces the severity of blooms, but it then sinks to the bottom of the lake, disrupts the development of microorganisms and reduces biodiversity. Bluestone additions began in the 1960s and continued until the federal government abolished the use of copper sulfate in bodies of water in the mid-1990s.

However, within a generation the natural state of the lake had been altered, and Killarney Lake now has one of the highest concentrations of sedimentary copper in North America. It is believed that the lake now suffers from what is known as “internal nutrient loading.” This means that the accumulated nutrients from centuries of natural inputs combined with decades of townsite and agricultural runoff have caused large amounts of phosphorus to settle on the lakebed. Consequently, the algae problem has become exacerbated in recent years.

Without the “instant solution” of bluestone to correct the algae problem, the Killarney Lake Water Quality Committee had to work hard to find new ways of dealing with the issue. The committee was made up of members of town council, Ducks Unlimited Canada, the Turtle Mountain Conservation District, government agencies and other stakeholders. In the mid-1990s, a set of culverts with control gates were installed at the lake’s main inlet from the Long River. This project was designed to divert the river during spring runoff and other times of peak flow to reduce the amount of phosphorus entering the lake from surrounding agricultural land.

At this time, a volunteer program was initiated to monitor the lake’s water quality, as well as that of the Long River. The committee also oversaw the installation of a beach curtain, which isolated the beach from the rest of the lake and improved the quality of water in the swimming area. However, the curtain disintegrated after a few short years, leaving the beach empty and aesthetically unpleasant once again.

After years of frustration and lack of solutions, the committee stagnated and eventually became defunct. This all changed in 2009 when the lake experienced a severe algae bloom, coinciding with a fish kill that was isolated to a small bay area. As a result, town council formed the new Killarney Lake Action Committee to address the issue.

New faces have generated creative ideas and new ways of addressing the lake’s problems. Mechanical methods such as aerators assist in adding dissolved oxygen to the lake, and a fountain has been installed in the bay area of the lake to help ensure that a fish kill does not happen again. Another local initiative involves the use of a skimmer to remove excessive algal growth from the lake. This process was attempted over the last summer with the understanding that surplus nutrients would be removed along with the algae. Although this method is theoretically effective, the harvester was unable to collect large quantities of algae, and the amount collected was never accurately measured.

Education has become the most effective weapon in the fight against invasive algae. Initiatives have been undertaken to create increased awareness of the issues surrounding nutrient loading and the damage that it can cause. The community has passed a ban on phosphorus-based fertilizers and has committed to becoming a “phosphorus-free town.”

They have also encouraged the implementation of shoreline management techniques to prevent erosion and reduce soil-based inputs into the lake. Property owners on the lake have been made aware of the importance of vegetated shoreline buffer strips to reduce the amount of runoff that enters the lake, and riparian areas such as wetlands have been preserved in order to filter the water and remove nutrients. Community support for sustainable methods of management has grown, even with the knowledge that algae blooms will continue to be a part of the lake’s future.

The Killarney Lake Action Committee is working in conjunction with the Turtle Mountain Conservation District and Manitoba Water Stewardship to ensure a healthy future for Killarney Lake. This problem did not present itself overnight; it was the result of many years of unintentional misuse. The committee recognizes that there is no easy solution to the problem of severe nutrient loading and that it will require constant monitoring and control to get the lake back to a more natural state.

For a small municipality like Killarney-Turtle Mountain, finding a cost-effective, positive and sustainable solution to the problem is difficult but essential. In the larger perspective, implementation of programs to address ecological issues must involve cooperation between citizens, governments and organizations. In this way, a comprehensive understanding of the long-term effects of human activity and intervention can be used to promote a healthy future for Manitoba’s environment.