Image of the Lake Leelanau Watershed and Lake Leelanau in the winter.

Watersheds 101 and Our Impact on the Lake Leelanau Watershed

The new year brings new opportunities to learn! The Lake Leelanau Lake Association (LLLA) is beginning a new campaign to educate our community on matters of importance to watershed protection. The first in this series is here to put the “watershed” in Watershed Wednesdays! But what exactly is a watershed? Why is understanding watersheds so important? And, how is land use affecting the Lake Leelanau Watershed and our lake? We invite you to read our latest blog to find out!

What is a Watershed?

You have probably heard of the term “watershed” but what does it really mean? A watershed is defined as an area or ridge of land that separates waters flowing to different rivers, basins, lakes, or seas. Let’s break that down.

A watershed is an area or ridge of land. But what does that have to do with water? Think of a funnel. When you pour water into a funnel, it flows down the edges and through the spout. The highest parts of the land that surround a water feature are like the edges of the funnel, and the water feature is like the spout. 

The shape of the land determines where the water goes when it flows. The variation in the landscape is like if you molded clay on the inside of the funnel in ridges, acting as hills, ridges, crests, and other types of elevation. These variations in the elevation channel the water and affect the direction of water flow, which ends up at the basin of the watershed. That is why watersheds are also called “drainage basins.”

Delineating a Watershed

What defines the area of a watershed? Continuing with the funnel analogy, think of several funnels standing next to each other in a clump. Each funnel is like a different watershed, and they are all defined by the highest points that surround the drainage basin. 

In reality, the edges of the funnels are the hills, mountains, and ridges of a landscape. When water flows down one side of a hill, it leads into that side’s corresponding watershed. If it flows down the opposite side of a hill, it would flow into a different watershed. Watersheds are, therefore, divided by high elevation points in the landscape's topography, called watershed divides or ridgelines (see the diagram below).

Watershed diagram sourced from the Aquetong Watershed Association.
Watershed diagram sourced from the Aquetong Watershed Association.

Different Watershed Boundaries: Surface Water and Groundwater Boundaries

To make things slightly more complicated, there are different types of watershed boundaries — surface water and groundwater boundaries. The way in which the boundaries, or divides, were previously described most accurately corresponds to surface water boundaries. They are delineated from the topography of the land.

Groundwater boundaries are very similar to surface water boundaries. The water still flows from high points to low points, but the boundaries of surface water and groundwater are not always the same. The movement of groundwater happens in underground aquifer systems. These systems are impacted by the hydraulic properties of the aquifer, the input and output from the aquifer system, and the geological factors—like underground rock formations—that might block the flow of water.

Why is Understanding Watersheds Important?

Understanding the different types of watersheds is important for understanding how humans impact the bodies of water around which we live. It is easy to see that someone living on, or even a bit uphill from the lake, might affect the water. But now that you understand groundwater boundaries, you can see that even people who live miles away from the lake can still have an effect on the lake. 

Any kind of pollutant that goes on the land eventually ends up in the water, one way or another. So, think twice before you put anything on the ground or underground. Would you dump that same thing into the lake?

Maps of the Lake Leelanau Watershed base and boundaries in Leelanau County, courtesy of the Leelanau Conservancy.
Lake Leelanau Watershed base map and boundaries map courtesy of the Leelanau Conservancy.

Critical Areas in the Lake Leelanau Watershed

Now that you have a better understanding of watersheds, let's look at our own, the Lake Leelanau Watershed. As you look within the outline of the watershed, you can see the other water features, like the streams and wetlands, that drain into Lake Leelanau. This may give you an even better idea of how land use affects the water. 

Think about what happens in those areas that surround Lake Leelanau. Is there agriculture where fertilizers are used? Are there parking lots where oil spills can run off into the surface water or groundwater? Are there septic systems that have not been maintained that could be leaking into the groundwater?

To help you reduce your impact on our watershed, here are a few tips and tools recommended by the EPA:

  • Conserve water every day. Take shorter showers, fix leaks & turn off the water when not in use.
  • Don’t pour toxic household chemicals down the drain; take them to a hazardous waste center.
  • Use hardy plants that require little or no watering, fertilizers, or pesticides in your yard.
  • Do not over apply fertilizers. Consider using organic or slow-release fertilizers instead.
  • Recycle yard waste in a compost pile & use a mulching mower.
  • Use surfaces like wood, brick, or gravel for decks and walkways, which allows rain to soak in and not run off.
  • Never pour used oil or antifreeze into the storm drain or the street.
  • Pick up after your dog, and dispose of the waste in the toilet or the trash.
  • Drive less—walk or bike; many pollutants in our waters come from car exhaust and car leaks.

We urge you to use these maps and this information to gauge your impact on Lake Leelanau and its surrounding watershed. Even if you do not live on the lake, your activities still affect the lake!

The LLLA works in close collaboration with the Leelanau Conservancy, Leelanau Clean Water, the Grand Traverse Band of Ottawa and Chippewa Indians, the Michigan Cooperative Lakes Monitoring Program, and other Leelanau County lake associations and organizations to protect the water quality of Lake Leelanau. If you are interested in learning more about Lake Leelanau Watershed management efforts and the organizations working to protect and preserve the land and water, click here.

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