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2022 Carp Management Study
Why do we care?
Too many carp can have a negative impact on a body of water’s clarity. Carp are bottom feeders and tend disturb the sediment on the bottom of the lake, ultimately resulting in decreased water clarity.
How many is too many?
Studies suggest that carp biomass in excess of 200kg/ha typically have a strong, negative effect on lake habitat and water quality. While biomass below 100kg/ha is typically an acceptable level.
Where does Cross Lake fall in the range?
The estimated carp biomass for Cross Lake was 113.7 kg/ha. While slightly over the suggested 100kg/ha value, reducing carp biomass to 100kg/ha may not have a substantial effect on the lake ecology.
What prompted the study?
The carp study was a recommendation from the Limnopro Point Intercept Survey conducted on Cross Lake in 2021, suggesting an elevated carp population contributing negatively to our water clarity. it here. (see full survey below)
The Good, The Bad & The Ugly About Phosphorous
Why do we need to be concerned about phosphorus?
Why do we need to be concerned about phosphorus?
Why do we need to be concerned about phosphorus?
- Poor water quality is nothing new, and our local water problems didn’t just pop-up last year. It’s been around for a very long time.
- One sign of the lakes’ poor water quality is the green slime that collects along your lakeshore.
- In the 1970s, motorboat props could whip up a trail of soap bubbles that congregated into flotillas of foam. Laundry detergent was the principal source of phosphorus affecting our lakes.
What is it and how does it get in our lake?
Why do we need to be concerned about phosphorus?
Why do we need to be concerned about phosphorus?
Think of phosphorus as plant food because it makes a primary ingredient in fertilizer, along with potash and nitrogen. Phosphorus is essential for forming cell membranes in all living things. Plants and animals need phosphorus to grow.
If it's so good, why is it bad?
Why do we need to be concerned about phosphorus?
If it's so good, why is it bad?
- Excess phosphorus in the soil leaches into our waterways. Harmful algae blooms may be created when a surge of nutrients feeds the ever-present cyanobacteria (aka blue-green algae, which is deadly to wildlife and pets). When too much phosphorus in water and conditions are ripe, harmful algae blooms can occur. Even ordinary healthy algae will bloom to excess levels and will consume oxygen when decomposing leading to oxygen depletion and fish kills.
Common sources of phosphorus
Together we can make a difference.
If it's so good, why is it bad?
- Farm and lawn fertilizer
- Animal waste
- Yard clippings
- Wastewater
- Septic systems
- Soil erosion – no buffer along the lake shore causing the shore to wash into the lake
Adding to the phosphorus problem is “internal loading,” which are the sediments on the lake bed formed from decaying plants and animals over many years. Large boat motors and wind, which can cause waves that churn up the silty bottom of the lake, as well as the feeding activities of fish, especially carp, will reintroduce phosphorus that had settled on the bottom.
What can we do?
Together we can make a difference.
Together we can make a difference.
There is no silver bullet or single solution to the phosphorus problem; however, following best practices will help lead to a solution.
- Adding rain gutters
- Restoring your shoreline to natural habitat – adding plants to your rip rap
- Keeping yard waste out of the lake
- Keeping domestic and farm animal waste out of the streams and lake
- Make sure your old nonfunctional septic tanks are caped or removed
- Don’t drain your wastewater or sewage into the lake or near the lake when camping
- Eliminate soil erosion by planting a buffer at the shoreline with trees, bushes, and native plants
- Help by eliminating big waves from motorboats that stir up the lake bottoms.
- Wake boats tear the bottom of the lakes, large motorboats, and personal watercraft can damage shorelines. Make every effort to stay 300 ft. from the shoreline.
- Reduce or eliminate hard surface run-off from roads, roofs and driveways
- Planting rain gardens:
Together we can make a difference.
Together we can make a difference.
Together we can make a difference.
Since 2013 the Snake River Watershed Management Board has completed erosion and pollution control projects, which have reduced phosphorous pollution to the snake river system by 29,000 lbs. per year.
For more detailed information, check out the links in “Resources”:
Resources
Water quality data for Minnesota lakes and streams
Minnesota Nutrient Reduction Strategy
Living Green yard and garden tips
Fertilizers (MN Dept. of Agriculture)
WATER QUALITY meetings - A great opportunity to met your neighbors and make new friends!
Our meetings are fun!
And sometimes we just kick back.
Secchi testing with the tube
Weed Rakes
How to use the Weed Rake by Jerry Trent:
Guidelines for those who are using a weed rake to control AIS:
The manufacturer of the Aquatic Weedcutter suggests moving the cutter towards deeper water, letting the cutter bar fall to the bottom of the lake, and then pulling the cutter towards you in a series of strokes (kind of like raking). This should cut the Cutleyleaf Pondweed, which will float to the surface. Pick a calm day since you will need to stop from time to time to use a leaf rake, pitchfork or landing net to skim the weeds off the surface and throw them up on shore to dry and dispose of later.
We need to strongly emphasize the need for you to remove the cut weeds from the lake/river. This is a DNR regulation which the Cross Lake Association fully supports. We do not want your “mess” to float to someone else’s waterfront. Curleyleaf Pondweed has a lot of nutrients in it, and if it decays in the water during the summer, it will release those nutrients and encourage algae to grow. Curleyleaf Pondweed should be cut from mid-May to about the end of June.
In general we don’t encourage cutting after spring time because you will be cutting good native aquatic plants which are needed for fish habitat and oxygenation of the lake/river.
During the summer it is common for aquatic plants to break free due to normal dieback or due to boat activity, and wave action. We encourage you to remove this vegetation from the lake/river also. Thanks for helping to make a difference in Lake quality.
A variety of rakes can be found on Weedersdigest.com or Amazon