Might living smarter in Muskoka mean measuring time like a lake?

By Norman Yan.

Time is actually a tricky concept.

Wikipedia defines it as “the continuous progression of existence that occurs in an apparently irreversible succession from the past, through the present and into the future.” OK, so metaphorically, time is the performance of life’s play on the stage of space. It’s what links cause to effect, action to consequence and experience, hopefully, to growth and learning. But Einstein taught us that time is not constant. It’s relative to your frame of reference. Our communication satellites wouldn’t work if Einstein’s amazing and proven idea wasn’t programmed into their control systems.

Events in time differ in importance to living organisms. For example, a cold year won’t matter to the hemlocks in my yard because they live for centuries, but sure will to the geranium we just planted. What about lakes? How does time’s play work for them? Might it vary from lake to lake, and what might this mean for management?

Muskoka lakes are considered “young.” They emerged from the receding ice just over 10,000 years ago. How time matters now for our lakes can be captured in what is called water residence time, i.e. how long an average drop of water stays in the lake before flowing downstream. Residence time is calculated as the lake volume (in m³) divided by annual outflow volume (in m³/yr), and it varies a lot among lakes. For example, Lake Superior has a residence time of about 200 years, but Lake Erie is just 2.5 years. Locally, because Lake Muskoka’s watershed is so much larger, the lake receives a much larger annual input relative to its volume than Lake Joseph, the water residence time of Lake Muskoka is only about one year, while that of Lake Joseph is about 20 times longer.

Now consider a bathtub filled to its overflow drain with cold water. If you switch off the cold water tap and turn on the hot water, it takes about three full flushes before the whole tub is filled with hot water, because the tub doesn’t drain just the cold water contents, but a mix of what’s in the tub and the hot inflow. Lakes, mixed by the wind, have similar hydraulics. So, it can take Lake Joseph 60 years to respond to a step change in the chemistry or temperature of inflows, but only three years for Lake Muskoka.

What might this mean for management? A lot. Lakes respond to newly applied policies on their own unique time frames, even if the policy is applied everywhere at the same time. Secondly, if you want to try something new, it makes sense to try it out first in a lake with an inherently quick response time, so you learn if the new approach works. Thirdly, understand that lakes with long response times (eg. Joseph vs. Muskoka), are still responding to policies from past decades, not just recent years. Finally, consider adopting a First Nations perspective, taking a view longer than an election cycle. Most lakes work on that longer view.

If we remember the way lakes treat time, we will be willing to act now to protect our lakes even when those decisions won’t bear fruit for a decade or two. And we will avoid the trap of failing to act to correct known threats when current conditions still seem OK, knowing that the lakes are only slowly responding to those problems. Our grandkids will thank us for those wise anticipatory actions, but they may not forgive us if we prove slow to act.

If you are a grandparent living on Lake Joseph, the lake outside your cottage is reflecting inputs over your entire life; but if you live on Lake Muskoka, the lake reflects decisions made over the most recent election cycle. Quite a difference.

This is #2 in the Muskoka Watershed Council series of articles, Living Smarter in Muskoka. Its author is Dr. Norman Yan, Director and founding Chair of Friends of the Muskoka Watershed, long-time Muskoka resident, and a retired environmental scientist who seems to understand how lakes think. The series is edited by Dr. Peter Sale, Director and Past Chair of Muskoka Watershed Council.

This article was published on MuskokaRegion.com on June 7, 2025.