Green Lake is a 1,259-acre, poorly buffered lake (total alkalinity of below 25 mg CaCO3/L) located in Seattle, WA. This urban lake has an average depth of 13 feet, a maximum depth of 30 feet and has had a long history of cyanobacteria blooms dating back to at least 1916. The City of Seattle contracted with HAB to successfully apply 81,744 gallons of alum and 40,905 gallons of sodium aluminate over a six-day period in April 2016.
The buffered alum application increased water clarity from 9 to 19 feet and had no effect on lake pH or dissolved oxygen concentrations. The image above shows the Green Lake Coverage Map, with each individual application path represented by a single green line. HAB provides a coverage map to their clients on all projects.