Noise on Isle Royale

In August 2016, 2nd Lieutenant Erik Doering and I were contracted by a former professor, Christopher Plummer, to plan and execute recording trips to Isle Royale National Park and the Apostle Islands National Lakeshore as part of a NEA/NPS Imagine Your Parks Grant. The grant project, “Listening to Parks”, hopes to inspire people to visit and be conscious of the sounds within these parks. In 2022, recordings from this project were featured in the American Pavilion at the 2022 United Nations Climate Change Conference (COP27).

You can see the massive mounds of Canada’s Sleeping Giant Provincial Park and other land features atop Mount Ojibway, Isle Royale’s tallest point, and along most of its central ridgelines.  Much of the land is faint, but visible. Michigan’s Keweenaw peninsula, Michigan’s closest point to the island and where I grew up, is over 50 miles off the southern shore of Isle Royale.  You wouldn’t know it if you looked though. All you can see from the southern shores of Isle Royale are its small outlying islands and the immense ocean-like enormity of Lake Superior.

Is Isle Royale far from the sound of civilization though?  Unfortunately, not so much. There are two important things that you can’t see from most maps.  Boat traffic and air traffic.

The wonderful part about quiet places is that you can hear things at a great distance.  The terrible part about quiet places is that you can hear things at a great distance.  A single boat engine can be heard miles inland on Isle Royale, especially if you’re at a high elevation. Look again at the map of Isle Royale at the start of this article and you'll see the official water taxi route around the island.  Charter water taxis as well as private and National Park Service vessels also circle around the island. 

Boat traffic on Isle Royale is nowhere near as incessant as air traffic is though. Flights are constantly crossing within earshot of the island.  When I first arrived on the island, I began counting the amount of aircraft I could hear.  In the 10 hours it took me to hike the 7 miles to Lane Cove (our first camping spot), go out to record and then return to camp and sleep, I had counted over 100 airplanes fly over, an average of one every seven minutes.

Once I got back to the mainland, I decided to do some research. Isle Royale, unfortunately, finds itself right in the middle of a major Canadian flight path. Most of this traffic is going to or coming from Toronto Pearson International (YYZ), Canada’s busiest airport.  The map above shows Canadian flight paths and air space around Isle Royale. International flights from places in the USA like Chicago and Minneapolis also cross through the island. I wanted to know, then, how many planes fly over Isle Royale in a day?

Using the flight tracker Flightradar24, which combines ADS-B, MLAT and radar data to show live and historical flight traffic, I manually counted the number of planes that either directly crossed over or within 10 miles of Isle Royale each hour for a 7-day period from August 23rd through August 29th 2017. I took the average of this number to account for human error and daily flight pattern differences from weather and other factors.

While this metric of counting airplanes crossing through or within 10 miles of Isle Royale doesn’t account for a host of factors that can affect the sound (such as geography, the type of plane, its altitude, and speed), it does act as a useful baseline for the potential of flight noise within the park.

Here is what I found.

Based off of my testing methods, I found that 220 planes cross over the park each day.  

To contextualize this number, I decided to compare Isle Royale’s air traffic to other national parks. I collected data for the number of flight passovers from two other national parks, Yellowstone National Park and Olympic National Park, during the same 7 day period. Renowned field recordist Gordon Hempton claims that the quietest location in the continental USA, what he calls One Square Inch of Silence (OSI), is located within Olympic National Park. I also monitored the airspace in a 10 mile radius around OSI. I was also curious about the difference in local and non-local air traffic, so I noted all airfields within 125 miles of the center of each park.

At first glance, it may seem that Isle Royale has a similar profile of air traffic as Olympic and Yellowstone National Parks.  The monitored areas in Olympic and Yellowstone National Park are, respectively, roughly 3 and 7 times bigger than Isle Royale though. In these larger parks, a single plane passing through may not be audible in all areas of the park. Given how much smaller Isle Royale is, each plane passing over it will affect a larger percentage of the park.  Although a coarse metric, adjusting the size of each of the sites to be the same as Isle Royale (as I show on the the graph on the right above) reveals more of this disparity.

Cities are louder than rural areas.  It should not come as a surprise that Olympic National Park, which has two multi-million population metropolitan areas and nearly 100 airports nearby (3 of which are major international airports), would have the most amount of air traffic out of three parks.  Seattle Tacoma International airport alone had an average of 1,130 plane landings/takeoffs a day in 2016. This makes it surprising to consider that the quietest place in the continental USA may be within Olympic National Park. Compared to the other sites I studied, One Square Inch of Silence has substantially less air traffic, although the monitoring size for the OSI is substantially smaller as well.

I was even more surprised to see how small the difference in the air traffic between these parks was. Both Yellowstone and Isle Royale have 1 airport with more than 200 landings/takeoffs a day and less than 25 other airports nearby.  The largest nearby city for both parks has a population around 100,000.  Despite being substantially more rural areas, they only have 10% and 20% less air traffic than Olympic National Park. 

And why is this?  The location of our cities affects noise pollution patterns both regionally and globally. A fair amount of the air traffic around Olympic National Park originates locally as a result of the major urban centers.  This is not the case for Yellowstone and Isle Royale.  Yellowstone's central location in the USA puts it in the middle of flyover country for both transcontinental flights between major USA urban centers and international flights. The same is true of Isle Royale and its location between major Canadian cities. 

The airways of the world mimic the patterns that highways and railways have in connecting urban centers, but on a global scale.  While air traffic may not visually transform the shape of our world as much as land-based transportation does, air traffic still has an effect on natural environments and humans.

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If you'd like to see a more in-depth look at the data I collected, here's a link to a spreadsheet with every flight passover at each park laid out by hour and day. https://drive.google.com/open?id=1PX-DTJB0FP91NUeM41z3B-XPUFZHTzwTUTUempT9kmM

Listening To Parks