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Study Shows That Bonfires Can Cause Lake Problems
If you enjoy a bonfire near the shoreline, remember to grab a shovel after the fire is out and dump the ashes inland to prevent the phosphorous in the ashes from seeping into the lake, according to University of Idaho researchers. Or better yet, consider moving your fire pit inland, far away from the shore.
Rains, winds, and other natural happenings carry the ash into the waters.
An average bonfire containing 22 pounds of firewood produces enough phosphorous to raise the phosphorous level 1 part per billion in 350,000 gallons of lakewater - a significant amount.
Phosphorous stimulates an over growth of algae and aquatic plants, which decompose after they die and in several generations - cause a lake to fill up with muck prematurely and become a marsh.
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Weeds,The Good, The Bad, and the Nutrient Filters
There is a misconception that all aquatic plants are bad or create nuisances. Aquatic plants, in fact play a major role in the aquatic environment. These same plants that may sometimes cause problems for people, filter nutrients from the water, create habitat for fish and wildlife, produce food for fish and wildlife, provide nutrient buffers, and protect shorelines from erosion. Without native aquatic plants in any lake, water quality and recreational use would take a dramatic change for the worse. The usual consequences are massive algae blooms, low water clarity, shoreline erosion, and negative changes in fish population composition and structure.
Although, all native aquatic plants are important, some tend to be of more benefit than others. Emergent plant species such as bulrush typically are more important than some other species or growth forms. These types of aquatic plants have the ability to remove a substantial amount of nutrients from the water. Some, including bulrush can actually remove pollutants such as heavy metals from the water. Emergent species combined create the largest and most beneficial amount of fish and wildlife habitat of all aquatic plant types.
Lakeshore owners and lake associations are continuing to increase their knowledge about the value of emergent aquatic plant species. Several lake associations and a number of lakeshore owners have recently decided to plant these important species in areas of lakes where they have disappeared. We have worked closely with these concerned lakeshore owners in determining locations of historical stands of aquatic species and providing technical assistance with regard to planting techniques and sources of plant supply. I encourage lakeshore owners to get involved with their local lake association. The cumulative effect of even the little things you do to make your lake better add up to a better lake environment however, you should remember the reverse is also true.
We do realize that aquatic plants sometimes cause problems for people who use surface water for recreation. However, some aquatic plants can be removed by various means in order to facilitate access to open water. In most instances a permit for such removal is required and can be obtained through the Regional Fisheries office in Brainerd.
Available methods of control are hand or mechanical or approved aquatic herbicides. A permit is required for any use of aquatic labeled herbicides in public waters and for removal of any amount of emergent aquatic plants by any means. Alternatives to plant removal include a reduction in the amount of nutrients available for plant growth. This can be accomplished by reducing nutrient-laden runoff from adjacent shoreline by leaving buffer strips composed of grasses and shrubs along the shoreline. Another is to use either no phosphorous or low phosphorous lawn fertilizers. Other alternatives are more long-range and include the reduction of nutrients through the entire watershed.
A new product for mechanical control of aquatic vegetation called a Weedroller came on the market in 1992. Over the past two years we have been studying the impact of the device on the lake bed, spawning fish, and aquatic vegetation. The results of our review have provided us with information to suggest regulatory changes are in order. Our reasons for these requested changes are that this device operates much differently than any other approved aquatic plant control device Consequently it could, if used improperly, have long-term, detrimental impacts to the aquatic environment and ecosystems of area lakes. We have observed a number of problem areas. These include damage to fish nests and spawning areas during the period from May 15 through June 20, free-floating aquatic vegetation deposited off site, silt plumes moving lakeward and downwind resulting in deposits off site, and loss of critical emergent aquatic plant stands. The Weedroller can be of benefit to lakeshore owners when regulated and operated judiciously.
Exotic aquatic species have been on the minds of most lakeshore owners and lake users over the past several years. The main concern has been with Eurasian water milfoil and the consequences of its infestation. Clearly, since Eurasian water milfoil was discovered in Bay Lake, our local lakes are not immune to the problems such as those in metro area lakes. The immense amount of recreational boating on local lakes provides a possible route for transport of exotic species such as Eurasian water milfoil or zebra mussels. Local lake associations such as Gull Area Property Owners Association and the Whitefish Property Owners Association have been leaders with their BAG IT program. This program provides training for exotic species identification and shoreline surveys for Eurasian water milfoil.
Terry Ebinger
DNR Region 3
Aquatic Plant Management Specialist
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