What is Alum?
Aluminum sulfate (alum) is a compound used to control the release of phosphorus from lake sediments to the water. The aluminum particles bind to the phosphorus and hold them in place at the lake bottom and thus keeps cyanobacteria blooms from occurring. When administered at the correct dosage, there is no harm to the ecosystem and lakes can experience clear water for decades.
Below are a couple of articles with lots of great information about alum, how it works, and more!
What alum is and how it works
History of Alum by Daniel Ackerman
Below are a couple of articles with lots of great information about alum, how it works, and more!
What alum is and how it works
History of Alum by Daniel Ackerman
Lake Carmi Alum Treatment
On 09/15/2025 with participation from the Vermont Department of Natural Resources, Lake Carmi began a historic Alum treatment. The treatment is made of a mixture of aluminum sulfate and sodium aluminate. This mixture will target legacy phosphorus reserves in the lakebed which worsen cyanobacteria blooms. If successful, this treatment will help lessen cyanobacteria in the lake and make Lake Carmi a healthier waterbody.
On 10/01/2025 local news stations came to document the historic alum treatment. We heard statements from all of our amazing collaborators. We thank all of the lake members and constituents that helped with the treatment!
On 09/15/2025 with participation from the Vermont Department of Natural Resources, Lake Carmi began a historic Alum treatment. The treatment is made of a mixture of aluminum sulfate and sodium aluminate. This mixture will target legacy phosphorus reserves in the lakebed which worsen cyanobacteria blooms. If successful, this treatment will help lessen cyanobacteria in the lake and make Lake Carmi a healthier waterbody.
On 10/01/2025 local news stations came to document the historic alum treatment. We heard statements from all of our amazing collaborators. We thank all of the lake members and constituents that helped with the treatment!
The State of Vermont and the VT Department of Environmental Conservation have approved a Phosphorus Inactivation Diagnostic Study for Lake Carmi. The study was performed by Barr Engineering of Minneapolis, Minnesota and completed in 2024.
They looked at data from within the lake and throughout the watershed to determine whether an in-lake Alum treatment is the best course of action. Click the link below for the latest draft of the study from Barr Engineering from the VT Department of Environmental Conservation website:
https://dec.vermont.gov/sites/dec/files/wsm/lakes/docs/Lake%20Carmi%20Feasibility%20Study%20on%20the%20Inactivation%20of%20Phosphorus%20in%20Lake%20Bottom%20Sediment_Draft_3_28_24.pdf
They looked at data from within the lake and throughout the watershed to determine whether an in-lake Alum treatment is the best course of action. Click the link below for the latest draft of the study from Barr Engineering from the VT Department of Environmental Conservation website:
https://dec.vermont.gov/sites/dec/files/wsm/lakes/docs/Lake%20Carmi%20Feasibility%20Study%20on%20the%20Inactivation%20of%20Phosphorus%20in%20Lake%20Bottom%20Sediment_Draft_3_28_24.pdf
Lake Carmi Watershed Phosphorus Study
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