Final Report - Flathead County, Montana

mains were located in the commercial areas along the two major highways that pass
through Evergreen. The septic tank effluent mains serve the bulk of the residential
areas located away from the highway corridors.
The area served by the Evergreen sewage collection system totals 2,199 acres.
During the original construction project of the sewer system, a total of 590 conventional
services and 1,149 septic tank effluent services were installed. The split between
conventional and septic tank effluent was roughly 1 to 2. This split has remained fairly
constant throughout the life of the system. As of March 2012, there were approximately
2,520 homes and businesses connected to the system. Over 1,600 of these sewer
customers are served by septic tanks.
The Evergreen Water & Sewer District does not own its own wastewater
treatment facility. Instead, Evergreen conveys the wastewater it collects to the City of
Kalispell Wastewater Treatment Plant (WWTP) for treatment and disposal. In June
1990, Evergreen and Kalispell entered into an Interlocal Agreement that defined the
conditions under which Kalispell would receive and treat sewage from Evergreen.
Among other things, this agreement established a sewer service area for Evergreen, the
sewer treatment rate to be paid by Evergreen to Kalispell, and the maximum daily flow
that Evergreen could send to Kalispell. Property outside of the established sewer
service area could not connect to the Evergreen sewage collection system without
explicit approval of the City of Kalispell.
The term of this agreement is 25 years and it will expire in June of 2015.
Evergreen and Kalispell are presently negotiating a new agreement to replace the 1990
Interlocal Agreement and extend the relationship where Evergreen will collect and
convey sewage to Kalispell for treatment and disposal. Since Evergreen does not own
or operate a wastewater treatment facility, the remainder of this section will pertain to
the Evergreen Sewage Collection and Conveyance System only.
POPULATION AND FLOWS:
Data from the United States Census Bureau from the past three censuses
indicates that the Evergreen area has grown steadily during the past two decades.
Those census results are tabulated as follows:
Table EG1 - Evergreen Census Data – 1990 - 2010
Year Population
10 year
Change, %
Annual
Change, %
1990 4,109 - -
2000 6,215 51% 4.2%
2010 7,616 23% 2.1%
Sewage Treatment in the Flathead Basin 27