Upper Prior Lake Alum Treatment Update

On Tuesday, May 26^th, the first-ever alum treatment took place on Upper Prior Lake. This process was expected to go on for 8-11 days, and was finished on Wednesday, June 3^rd.

Algae are free-floating, microscopic organisms that are commonly found in lakes. While it does support the development of juvenile and adult fish, excessive growth of invasive algae can cause serious water quality problems. About five years ago, The Prior Lake-Spring Lake Water District enlisted the help of HAB Aquatic Solutions and embarked on a $1 Million initiative to fight the algae growth. HAB Aquatic Solutions is a Nebraska-based company that travels across the country to combat unwanted algae growth through aluminum sulfate treatments.

Aluminum sulfate (alum) is used to improve water clarity and reduce algae blooms by reducing phosphorus levels in the lake. Phosphorus is a nutrient naturally found in lakes, however due to development and runoff, excess amounts of phosphorus feed algae blooms. Alum treatments bind phosphorus and creates something called “floc”. Floc is a fluffy white substance that eventually settles on the bottom of the lake to prevent phosphorus from being released from the sediment, thus making it unavailable for algae growth.

As of Thursday, May 28th, the HAB crew had applied approximately 45,000 gallons of the 198,500 gallon total dose for Upper Prior Lake. The HAB team utilizes precise calculations and an on-board computer system to ensure that alum application is precise and uniform by integrating the location of the barge with GPS, the barge speed, water depth and alum flow rates. This technology creates a much more accurate process and confirms the complete coverage of the lake.