Isanti Soil & Water Conservation District
The Alum Treatment has Begun!
Tuesday September 13th the alum treatment application began. The small barge went back and forth injecting alum into the water over the deepest parts of the lake. During this application period, the alum will sink to the bottom of the lake and collect algae and phosphorus as it sinks. Once on the lake bottom, it will act as a barrier to prevent more phosphorus from entering the lake from the sediments. The alum treatment will do wonders for the health of Blue Lake!
The application will take place Tuesday September 13th through Thursday September 15th. The boat launches on Blue Lake will be closed during that time to ensue the application can work efficiently and effectively. However, pedestrians may stop by to see the application taking place. If you take pictures that you would like to share with us, please email them to
Blue Lake to Receive Alum Treatment this September 2022
The dates have been selected for the Alum Treatment on Blue Lake! The Isanti SWCD has been working to protect the health of Blue Lake. An alum treatment has been selected as the next most logical and cost-effective way to protect it.
The alum treatment will take place from September 12th to the 16th. Both Blue Lake Public Boat Launches will be shut down during the application on the 13th, 14th, and 15th to ensure the application will work as effectively as possible. Residents are also advised to avoid boating on Blue Lake during these dates. Parking will be limited at the Stanford Public Boat Launch on the 12th and the 16th due to the alum equipment set up. If you are planning to use the boat accesses on these days, please consider making other plans. As soon as the application is over, people may resume using the lake as normal!
Diagnostics taken on Blue Lake indicate it is at risk of becoming an impaired water body due to an excess of phosphorus in the lake, which fuels algae blooms. The Isanti SWCD is taking steps to reduce the amount of phosphorus in Blue Lake and assure it does not become impaired. Multiple conservation projects in the area surrounding the lake have already been completed by the Isanti SWCD however, these projects are not enough. Studies on Blue Lake indicate an alum treatment is the best next step to protect the lake.
Alum is a safe and widely studied option for lake treatments to reduce the amount of phosphorus present in the water. It works by forming a fluffy aluminum hydroxide solid called a floc when applied to water. As the floc settles, it removes phosphorus and particulates (including algae) from the water column. Therefore, after the treatment, the water should be noticeably clearer! The floc settles on the sediment where it forms a layer that acts as a blanket for phosphorus, so phosphorus released from the sediments cannot enter the water. The alum treatment will achieve 164% of the phosphorus reduction goal the Isanti SWCD set to keep Blue Lake Healthy!
The Isanti SWCD secured a Clean Water Fund Grant to pay for the alum treatment. The treatment also would not be possible without the Blue Lake Improvement District, which is providing a necessary 25% grant match and has been working with the Isanti SWCD to make this a reality. The first treatment is happening this September and a second treatment will be done in 2024. Regular updates are available on www.isantiswcd.org as well as answers to frequently asked questions.
Blue Lake Alum Treatment Dates Announced!
The alum treatment will be taking place September 12th – 16th.
The actual application will occur on the 13th-15th while the other days shall be used for set up/ take down. We ask that people avoid boating on the lake during the treatment days so that the alum application can work as effectively as possible. It is also possible the Blue Lake Public Boat Launch in Stanford Township will be shut down during the treatment days, in which case this page will be updated and a notice will be provided at the access. Thank you for your understanding.
The Isanti SWCD will be sharing pictures and video footage throughout the treatment!
The Minnesota Pollution Control Agency has issued a letter of support for the alum treatment on Blue Lake. You can view the letter here. The letter declares that the MPCA approves the alum treatment on Blue Lake, and that they require the lake's pH is monitored during the treatment. The Isanti SWCD will monitor Blue Lake for a variety of lake health measurements (including pH) before, during and after the treatment.
Reduce Your Wake for Blue Lake
A large wake from boats, and especially wake boats, has a negative impact on lake health. Large wake can rip-up shorelines, causing erosion, and rip-up lake bottoms. On Blue Lake this would be especially devastating, because it would reduce the effectiveness of the alum treatment. The longevity of the treatment works by forming a barrier, like a blanket, on the lake floor to prevent phosphorus in the sediment from entering the water. If this blanket is disturbed the treatment will not be able to trap that phosphorus. The phosphorus will then enter the water column and lead to algae blooms. Please be conscientious of this, and reduce your wake on Blue Lake.
Click here for a handout about wake, wake boats, and lake health.