Erosion Control On Land
When you remove sod, there is a risk of soil erosion. The best prevention is to apply mulch to the planting beds but only in the upland zone.
Mulch holds moisture, helps control weed problems and gives a more landscaped look for those who may have concerned neighbors.
Note that it is not necessary, and in fact would be detrimental, to put plastic under mulch as conventional landscapers sometimes advocate. In establishing a shoreline buffer you want to encourage dense, vegetative growth, unlike a garden with open soil areas between plants. There are several varieties of mulch materials available.
The key is to select a type of mulch that knits together and holds in place.
- Use a shredded hardwood mulch, not wood chips that are more likely washed away.
- Manure and compost are not good selections since they deposit nutrients into the lake.
- Avoid placing mulch near the shoreline where it can easily be washed into the lake. Use erosion control fabric in the transitional zone.
- On steeper slopes, use erosion-control mats to hold the soil in place.
Erosion Control Fabrics
Erosion-control fabrics are available from commercial sources. Choose a 100% biodegradable material suited for the characteristics of your site (steepness, amount of runoff, etc.). Coir (coconut fiber) is known for its longevity, while Jute, wood fiber and straw biodegrade faster. Ask your local vendor to help you select the appropriate erosion control fabric for your site.
Coir fabrics come in multiple brands and forms. For shoreline projects, there are two types that are more commonly used and that work in all three shoreline zones.
The first is a loosely packed blanket of coir fibers within a biodegradable natural fiber net. It works especially well within the transitional zone. Plants can be easily installed through a cut in the fabric.
The second type is a coir fiber twine that looks more like woven netting. It is better for steeper slopes, stream banks and more severe conditions. It will stay in place for a longer period of time.
Wood fiber blankets are made of curled strands of wood fiber placed between photodegradable or biodegradable netting. These are good to use in stabilizing upland slopes that have been seeded. Wood fiber blankets are available in different weights depending upon conditions and are generally less expensive than coir.
Straw blankets are used for short-term needs. They degrade in 60 days to about 10 months depending upon the type chosen. They should be used in upland situations, for example over a seeded slope.
Another erosion control option is using pregrown mats of plants. Available through select nurseries, plants are custom grown within erosion control fabric for site specific needs and the mats are staked in place.
There are some situations where a nonbiodegradable erosion control material is needed, such as a turf reinforcement mat. They are used in more severe situations such as sites with very heavy wave action, high stream flow velocities, or heavy runoff.
How to install:
Erosion control fabrics are installed with stakes. In addition to metal staples and plastic pegs, several types of biodegradable stakes are available:
- Hardwood stakes which are all natural but may take years to break down.
- Corn byproduct stakes which break down within a year
- Corn byproduct staples which completely degrade in three months but might not work as well in sandy soils.
Biodegradable stakes or staples should be used wherever possible.
Erosion control blankets are installed using different methods depending upon site specific conditions and uses. Ask for installation instructions from the product vendor.
Erosion Control In Water
Unless your property is located in a quiet bay, wave breaks are needed for successful aquatic plantings.
Wave breaks can serve two purposes: protection of shoreline and protection of vegetation from boat- and wind-created wave action.
Newly planted aquatics are easily uprooted by wind and boat-induced wave action. A wave break provides a calm, protected area for the plants to take root. Wave breaks are placed out in the water beyond the area where aquatics will be planted. The wave break device should be installed from the bottom of the lake extending above the water, ideally above the maximum wave height. It should be left in place for 1-2 growing seasons, and then removed. Wave breaks are often removed for the winter to prevent damage from ice.
Wave breaks can be constructed of plywood, double- or triple-layered snow fence, or chicken-wire fencing with silt fence installed with fence posts. Other options include brush installed between stakes or earth anchors, or a floating silt curtain. A DNR permit may be required to install wave breaks. Contact the hydrologist in your local DNR office for information.
Another protective technique for the shoreline is the use of coir logs. These are 12"-16" diameter logs or rolls made of densely packed coconut fiber within Coir fiber netting. They come in lengths of 15' to 25'. When staked against the shoreline, these logs provide protection from the waves. They will biodegrade over a period of about 5 to 8 years. Plants can be installed within the log, in front of the log, and behind it. By the time it biodegrades, these plants have stabilized the shoreline. Several different vendors carry coir logs and erosion control fabrics.
- Remember that erosion control immediately after turf removal is essential.
- Avoid using heavy equipment in shoreline areas. It can result in compaction of soils and damage to fragile plant root systems and contribute to soil erosion.