The City of Kalispell Advanced Wastewater Treatment & Biological Nutrient Removal Facility began operation in October 1992 to protect pristine Flathead Lake, the largest natural freshwater lake west of the Mississippi River. In August 2009, the City completed a two year plant expansion project to accommodate rapid area growth; the plant capacity was increased from 3.1 to 5.4 million gallons per day. The biological nutrient removal process was changed from the modified University of Cape Town to the modified Johannesburg process. In keeping with the concept of using only biological treatment, the improvements also included a biological state-of-the-art odor control system. The plant continues to use a Supervisor Control and Data Acquisition System and Programmable Logical Controllers.
The plant achieves outstanding removal of solids, nutrients and E. coli, all without the use of chemicals. As a result, the plant has received two national first place (2003 & 2007) and three Region VIII first place (1997, 2003 & 2007) Operations and Maintenance Excellence Awards from the U.S. Environmental Protection Agency; a Commendation of Excellence Award from the Flathead Basin Commission; a System of the Year Award from Montana Rural Water Systems; and a Biosolids Award from the Montana Water Environment Association.