The Filter Plant is located east of Sawmill Creek and is bounded to the north and west by Sawmill Creek, and by Bear Mountain to the east. Public Water System in Sitka, Alaska Blue Lake has been the main source of water for the City of Sitka Public Water Supply since 1986. Prior to 1986, water was supplied from Indian River. The Indian River system remains functional as a backup water supply. The Indian River system is used during times when the Blue Lake system is taken off line to complete required inspections and maintenance.
Blue Lake is a reservoir surrounded by mountains and steep terrain.
The reservoir has a surface area of 1,330 acres at normal maximum levels with a drainage area of 37 square miles. The watershed is formed by steep mountain slopes that plunge to narrow glacial valleys. The reservoir has a mean depth of 171 feet with a maximum depth of 468 feet. A topographic map of Blue Lake is included in Figure 3 in Appendix B . Camping is allowed with a permit issued by the City and Borough of Sitka.