Have you read the Muskoka Watershed Council’s latest watershed report card?

Every four years since 2004, the Muskoka Watershed Council has released an extensive examination of the health of Muskoka’s watershed. The latest version—MWC’s fifth—was unveiled on July 19 and it shows that, overall, the watershed is in good shape but there are areas that are vulnerable or stressed.

The report card is a “science-based evaluation of the health of our watershed using a variety of environmental ‘health’ and ‘threat’ indicators,” noted the MWC in a media release. The health indicators include phosphorus and calcium concentrations in lakes, benthic macroinvertebrates, and interior forest habitat while the threat indicators include climate change, invasive species, fragmentation, and species at risk.

A watershed is an area of land that drains to a river, lake or stream. The Muskoka watershed has 19 subwatersheds, which lie totally or partially within District Municipality of Muskoka boundaries, and all of which eventually drain into Georgian Bay. Three of the subwatersheds are in the Huntsville area: the Mary Lake, Little East River and Big East River watersheds.

The report card grades each of Muskoka’s 19 subwatersheds at one of three levels—‘not stressed’, ‘vulnerable’ or ‘stressed’—for each of the health and threat indicators. In the Huntsville area, all three subwatersheds were classed primarily as ‘not stressed’ for the indicators, with the following exceptions:

All three of the Huntsville-area watersheds are vulnerable for fragmentation, as is the nearby Lake of Bays watershed.

In the Mary Lake watershed, which encompasses the Town of Huntsville and all four of its largest lakes, 26 per cent of the land is fragmented. In the Big East River and Little East River watersheds, 21 per cent and 33 percent respectively of the land is fragmented. In the Lake of Bays watershed, that number is 27 per cent.

All four of these subwatersheds are also vulnerable for climate change. Lakes in Muskoka have approximately three weeks less winter ice cover than in 1975, notes the report card, and summer water temperatures in Muskoka’s lakes are 0.5°C warmer on average than in 1980.

The Mary Lake watershed is also vulnerable for invasive species, with the following reported in the area: Phragmites, Giant Hogweed, Japanese Knotweed, Rainbow Smelt, Rusty Cray Fish and Spiny Waterflea.

The Little East River, with just 49 per cent of its land interior forest, is considered vulnerable. The report card notes that interior forest ecosystems are at significant risk if interior forest cover in a watershed falls below 15 per cent (Environment Canada, 2004). Subwatersheds with greater than 50 per cent interior forest, which ensures that “interior forest bird species and sensitive mammals have adequate habitat and that there is minimum conflict with humans,” were classed as not stressed. Those with between 20 and 50 per cent interior forest are considered vulnerable; invasive species may pose a greater risk.

Want to see how your area or lake is doing? The 2018 Muskoka Watershed Report Card has an online interactive multimedia component, including story maps, and a variety of infographics to help you see more specific details.

For more information on the work of the Muskoka Watershed Council and to view both the online interactive and downloadable PDF versions of the report card, visit muskokawatershed.org.

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