By Dixie Sandborn
There has been a flood of information in recent years about shorelines, erosion, erosion control, habitats along shorelines and shoreline ecosystems. For homeowners living along shorelines of inland lakes, it’s important to understand how to enhance their shoreline property while trying to minimize the effect on the shoreline ecosystems.
First, what is an ecosystem? An ecosystem is a natural unit consisting of all plant, animal and microorganism (biotic or living) factors in a given area, functioning together with all the physical (abiotic or nonliving) factors of the environment.
In researching this topic of shoreline ecosystems, the publication Shoreline Alterations: Natural Buffers and Lakescaping by the Minnesota Department of Natural Resources states, “A natural shoreline is a complex ecosystem that sustains fish and wildlife and protects the entire lake. Native vegetation along the shore acts as a buffer zone, intercepting nutrients and reducing run off, erosion, and sedimentation. Aquatic plants provide food and shelter for ducks, songbirds, and other animals while reducing problems caused by Canada geese and burrowing muskrats. Plants growing in and near the water are critical for wildlife and fish habitat and a healthy lakeshore. Tall plants like bulrush, lake sedge and cattail can reduce the energy wave action to minimize erosion and help maintain water quality.”
There is a wealth of information available to homeowners living along lakeshores. Many of these fact sheets, books and articles address the thousands of lakes in Michigan, Minnesota and Wisconsin. These three states have the most lakes in the lower 48 within their states’ borders due to glacial action.
In Michigan alone, there are approximately 11,000 inland lakes with a surface area of more than five acres, with nearly 3,500 lakes with over 25 acres in size. Of these lakes, 730 of them are designated as public access lakes. It is vitally important for lakeshore property owners to care for the lakeshores to help maintain a good balance between the natural habitats and the recreational uses of the lakes. It is equally important for the recreational users to be vigilant with the use of the lakes and lakeshores as they enjoy fishing, boating, swimming and other activities on, in or near the water’s edge.
According to the 2007 National Lake Assessment conducted by the U.S. Environmental Protection Agency (EPA), “Poor lake shore habitat is the biggest problem in the nation’s lakes.” The results of this study report on lakes that are more than 10 acres in size and at least a meter deep. There were 1,028 lakes tested, including 50 Michigan lakes. The findings of the report state that inland lakes across the nation need better care. The interrelationships of many physical, chemical and biological factors were evaluated for each lake.
A healthy lake needs to meet certain criteria. Healthy lakes exhibit these traits:
• Not overloaded with nutrients.
• Safe for recreation.
• Has aquatic habitat that supplies food, cover and spawning areas.
• Has natural shoreline plants to support a variety of wildlife.
Habitat is defined as a place where species get what they need to survive—food, water, cover and a place to raise their young. Habitats along a natural lakeshore support a variety of wildlife species in the water and the adjacent land. These ecosystems are diverse and each has its own personality. Each lakeshore property has its own ecosystem. People have control over some actions that effect the ecosystem in how the land is managed, yet people have no control over certain factors like the amount of rain or snow a lake receives.
Why is habitat so important for Michigan lakes? Michigan lakes support 24 species of amphibians, 25 species of reptiles, 87 species of birds and 19 species of mammals, according to a study by O’Neal et al. in 2006. Also, there are 65 species of Michigan-native fish, 18 of which are identified as species of greatest conservation need in the Michigan Wildlife Action Plan. They’re also supported by critical habitat found in the littoral and nearby areas, according to a study by Eagle et al. in 2005.
A lake’s ecosystem also includes its watershed—an area of land that drains to a common point. The number one thing to remember about a watershed is whatever we do on the land affects water quality. Fertilizers, pet wastes, gas, oil and other contaminants may enter the lake through runoff. The water runs off the land has a great effect on the quality of the lake water. Managing runoff and practices to lessen contaminants is important. There is no new water. We must be vigilant in protecting our water and lakeshores.
Keeping your shoreline healthy is vital to the overall health of the lake. One of the biggest factors in the health of the shoreline is the plants that live on the land along the shoreline, as well as the submerged plants that live near the shoreline.
Plants on the shoreline or submerged in the water close to the shoreline are a problem for most lakeshore property owners. Unfortunately, most property owners want to remove all native vegetation and maintain a nicely manicured lawn, as well as add sand for a beach adjacent to the lake area for swimming and boating. The balance is educating property owners to learn about the vital role these plants play in the overall health of the lake. With the knowledge they gain, they will be able to make better decisions on how many plants to remove and how to still enjoy the recreational benefits of their lake.
Natural vegetation on the lakeshore enhances fish and wildlife habitat. Once established they are low maintenance and add to the beauty of our lakeshores. A major function of vegetation along a lakeshore is to filter pollutants from runoff thus protecting water quality. Native plants accomplish this by utilizing their deep root systems securing soil for filtration and stabilizing soil against erosion.
It is not only the plant life right next to the shoreline, but the plant life further from the shoreline that determines the health of the lake. A lakes ecosystem has plant communities that are divided into three distinct plant zones. Each of these zones plays a critical role in the health of the lake. These zones are:
• Upland zone. These plants are associated with dry soil, many times on slopes surrounding the lake.
• Wetland zone. These plants can withstand flooding or consistently wet soils as well as long periods of dryness.
• Aquatic zone. This area is in the lake and has four subgroups, depending on the plant structure.
There are also four types of aquatic plants that are critical to the lake’s health. All four groups of plants are found in the littoral zone of the lake. The littoral zone is the shallow and warmer part of the lake. This zone allows enough sunlight to penetrate the water to promote good plant growth. Because of the plant growth, there is an abundance of wildlife and fish in this area. The four types of plants in the littoral zone are:
• Algae, which have no true roots, stems or leaves and range in size from tiny, one-celled organisms to large, multi-celled, plant-like organisms.
• Submerged plants, which have stems and leaves that grow entirely underwater, although some may also have floating leaves.
• Floating-leaf plants, which are rooted in the lake bottom, but their leaves and flowers float on the water surface. Water lilies are a well-known example.
• Emergent plants, which are rooted in the lake bottom, but their leaves and stems extend out of the water. Examples are cattails and bulrushes.
A helpful resource for identifying and reducing shoreline erosion for property owners is Understanding, Living With, and Controlling Shoreline Erosion a Guidebook for Shoreline Property Owners by the Watershed Council. However, the easiest way to spot erosion and its possible causes is to walk along the shoreline or take a boat ride close to the shoreline. When looking for erosion, you will be able to identify if the erosion is naturally caused, human caused, site-specific (only on your property) or widespread.
Some possible causes of erosion:
• Overland runoff. This is water that flows over the ground instead of soaking into the ground. Runoff is a result of natural and human activities. Runoff carries soil particles and other pollutants, such as fertilizers, pet wastes, oil, etc. into the lake. This runoff may originate a long distance from the lake.
• Groundwater seepage and springs. Ground water seepage is a natural condition where the water table meets the land surface. These areas have characteristics of a wet spot, a wet layer in a steep bank or a flow of water.
• Removing vegetation. Erosion problems simply occur due to removing shoreline vegetation. The roots of plants hold the shoreline in place.
• Waves. Natural or man-made waves are the most common cause of shoreline erosion. Property on the windward side of the lake has the greatest impact.
• Ice action. As temperatures rise in the spring, ice is pushed up onto the shoreline; this impacts the bank and causes it to move back, creating an ice ridge. Ice ridges actually protect the shoreline from further ice damage and should not be removed.
Here is a quick list of the most noticeable signs of trouble:
• Large areas of bare soil along the shore, especially on a steep bank.
• Large or small gullies by overland runoff along the shoreline.
• Frequent landslides or excessive bank slumping.
• Noticeable recession of the shoreline over a period of time.
• Leaning or downed trees with exposed roots on the shoreline.
• Large patches of unusually cloudy (turbid) water near a lakeshore, especially during periods of high water.
Wave and ice erosion is hard to predict. Ice damage changes from year to year. The size of waves are largely dependent on two factors: wind speed and lake fetch. Fetch is the distance the wind can travel over water before meeting the land.
There is an online erosion calculator that can be used to find what the wave energy is at a particular site. To use the calculator, you need to use a lake map that shows the topography of the bottom of the lake. Many Michigan inland lake topography maps are available on the Michigan Department of Natural Resources site.
Wave energy should be calculated before any shoreline erosion control project begins. This will give you information on the how to select the best erosion control method for your particular project.
(The information is this article first appeared as a give-part series by Dixie Sandborn who is part of the Michigan State University Extension Service.)
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