As the weather warms and people are returning to the Northwoods, we’ve been busy scheduling our Shoreland Restoration projects.  I’ve been reviewing/designing a few plans and a lot of them have fire pits incorporated in them.  Several of the plans had firepits on the shorelines of their respective lakes and per my suggestion I’ve been able to convince the landowners to move them away from the shoreline. 

Firepits close to a lake can contribute to phosphorous runoff into the lake.  I’ve developed some guidelines for locating firepits. 

  • Locate fire pits away from shore and dispose of the ash.  Leftover ash is very high in phosphorous.  If the firepit is close to the lake, rain can wash the ashes into the lake and contribute to excessive weed growth and algae blooms.
  • I recommend locating firepits at least 50 feet away from the lake

Nitrogen, potash and phosphorous are the nutrients necessary for plant growth.  Once again, phosphorous is the key nutrient needed for algae and aquatic plant grown.  When phosphorous reaches the lake, it can fuel overgrowth of aquatic plants and algae.  Algae and algae blooms give the water the greenish tinge and can cause the toxic blue-green algae scum on the shorelines.  Excessive plant growth can decrease water clarity, interfere with recreational use of the lake and diminish oxygen for fish.

Rainfall does contain some phosphorous, which can increase when it hits a surface and picks up additional phosphorous.  Of course, there are other ways phosphorous can enter our water:

  • Decomposition of leaves
  • Excessive fertilizer application
  • Erosion of soil
  • Improper pet or human waste management

Grass clippings, leaves and aquatic plant material that wash up on shore all contain phosphorous, which is released as the material decomposes.  Things you can do to prevent excessive phosphorous include:

  • Using a mulching lawn mower and leave the clippings on the lawn as a natural fertilizer
  • Collect and compost leaves and clippings, or haul them away from the lake
  • Leave a strip of taller grass or shrubs along the lake to catch windblown and surface debris
  • Don’t burn leaves near the lake as it can destroy the organic matter, but release the phosphorous which can then be washed into the lake

Conservation Corner is a weekly article produced by the Forest County Land &Water Conservation Department. For more information contact Steve Kircher, County Conservationist-Land Information/GIS Director at 715-478-1387 or by e-mail at .