Green Lake, WA

The 2016 Green Lake alum treatment was successfully conducted by HAB Aquatic Solutions over a 6-day period from April 5 – 10… The treatment increased water transparency (Secchi depth) from 9 to 19 feet and changed the color from green to blue, and had no effect on the lake pH or dissolved oxygen concentrations.

http://friendsofgreenlake.org/2016/04/

The 2016 alum treatment is intended to reduce phosphorus levels in the lake, limiting cyanobacteria (blue-green algae) blooms and improving recreational use of the lake.

http://parkways.seattle.gov/2016/03/30/2016-green-lake-alum-treatment-to-begin-on-april-4/