USGS Water-Year Summary for Site 15087810

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	Available Parameters
	00010 Temperature, water(Mean,Min.,Max.)
	00060 Discharge(Mean)

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Water year 2023: 2022-10-01 to 2023-09-30

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USGS Water-Year Summary 2023

15087810 Sawmill Creek below Upper Tailrace near Sitka, AK

LOCATION - Lat 57°03'40", long 135°12'35" referenced to North American Datum of 1927, in NE 1/4 SE 1/4 NE 1/4 sec.34, T.55 S., R.64 E., City & Borough of Sitka, AK, Hydrologic Unit 19010212, (Sitka a-4 quad), on Baranof Island, in Tongass National Forest, at footbridge crossing at campground, 240 ft downstream from upper powerplant tailrace, 0.35 mi upstream from dam at Blue Lake, 1.2 mi upstream from mouth and 4.6 mi east of Sitka

DRAINAGE AREA - 38 mi².

SURFACE-WATER RECORDS

PERIOD OF RECORD - October 22, 2019 to current year.

GAGE - Water-stage recorder. Elevation of gage is sea level, from topographic map.

REMARKS -

MEASURED PREVIOUSLY (WATER YEARS); 1994-95 and 1998 to 2019 as a miscellaneous site.

Minor regulation above station by Sitka Public Utilities hydroelectric plant during periods 1920-23 and 1937-42. In 1959, Blue Lake Dam, 1.6 mi upstream, was completed. The area of the lake is 1225 acres. The dam is concrete with a spillway elevation of 342.0 ft above sea level. In 1960, the Blue Lake Hydro plant, located 400 ft downstream from gage, was put into operation. Water is taken from Blue Lake and piped via a penstock to Blue Lake hydro, through 2-3,000 kw turbines and discharged back into Sawmill Creek just below high tide level. This penstock also provides water for the City of Sitka and for the filter plant for the Sitka Sawmill. In the years following, Campground Hydro, a smaller generation plant was constructed about 1,000 ft below Blue Lake Dam. It also has a penstock from Blue Lake and discharges directly into Sawmill Creek. A fish bypass valve has been installed at Campground Hydro that automatically releases 50 ft³/s to the tailrace anytime the hydro plant is shut down. Another small generator was installed just above the Sawmill Filter Plant diversion from Blue Lake Hydro penstock with the capability of bypassing the filter plant and discharging back into Sawmill Creek above the gage site. Water that went to the filter plant was piped to the sawmill and eventually discharged directly into Silver Bay. The sawmill has since closed and water is now supplied to Sawmill Cove Industrial Park. Flow is constantly regulated except when Blue Lake is spilling.

WATER-QUALITY RECORDS

PERIOD OF RECORD - October 22, 2019 to current year.

PERIOD OF DAILY RECORD - WATER TEMPERATURE: October 22, 2019 to current year.

INSTRUMENTATION - Electronic water-temperature recorder set for 15 minute recording interval.

EXTREMES FOR PERIOD OF RECORD - Maximum recorded, 15.7 oC, July 31, 2020; minimum recorded 1.0 oC, January 21, 2022.