A century of service
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Lake Dorothy Hydro Project

Gold Creek Hydro Plant

The Gold Creek project, located in downtown Juneau, is a "run-of-the-river" plant. Its output depends on the flow of the creek. It was built in 1914 after fire destroyed the original powerhouse built in 1893. Installed capacity at construction was 800 KW.

In the early 1950's, AEL&P installed a new penstock parallel to the existing penstock at the Gold Creek plant and installed another 800 KW hydroelectric generator, bringing the installed capacity up to 1,600 KW.

The Gold Creek plant produces about 4.5 GWH of energy annually for AEL&P, but this production is seasonal. Energy production peaks May through November and drops off almost completely during the winter.

Gold Creek Fossil Plant (return to top)

The Gold Creek fossil fuel plant has five slow speed diesel engines capable of producing 7.9 MW. These engines became the nucleus of the AEL&P power grid after they were installed, and remained so until 1973, when the Long Lake Project at Snettisham came on-line. After Snettisham's availability, the Gold Creek fossil fuel plant was put on standby status as backup in case Snettisham goes off-line for an extended period.

Correspondence from July 1951 shows the foundation of the Gold Creek fossil plant was modified at that time to accept a new 1,200 KW Enterprise diesel generator, the first of the five engines now there. The Enterprise was chosen for its fuel economy, low noise level and low maintenance cost. It was purchased in August 1951 and installed in 1952 at a cost of about $186,000. In 1954, a second diesel generator was installed at the Gold Creek Plant. The other three engines were installed in later years.

Salmon Creek Dam and Powerhouses (return to top)

Work on the Salmon Creek Dam and the accompanying powerhouses began in May 1912 with construction of the lower powerhouse. The lower powerhouse was located just to the south of where Salmon creek meets Gastineau Channel. Work on the transmission line started in March 1913, and work on the dam began one month later.

To build the dam, a construction facility was built upstream from the site. Rock for building material was obtained nearby and transported to crushing equipment located on site. After the rock was crushed and greatly reduced in size, it was used as aggregate, a material that acts as a filler when it is mixed in with the cement used to make concrete.

The first concrete for the dam was poured into place July 24, 1913, and about thirteen months later, on August 13, 1914, the final concrete was poured, completing the dam and enabling it to go on-line.

When it was completed, the Salmon Creek Dam, designed by Harry L. Wallenberg, was an incredible feat of engineering for its time. At 168 feet high and 648 feet across at the crest, its design called for the first true constant-angle arch dam of its height and width class, and over 54,000 cubic yards of concrete was used in its construction. This unique design allowed an estimated savings of about 20 percent in the volume of concrete used as compared to the common type of arch dam built in that period.

Two powerhouses were built to make maximum power generation use of the water flowing from the dam. About one mile downstream from the dam was the upper powerhouse, known as Powerhouse Number 2. From it a flume carried water to Powerhouse Number 1 on the shore of Gastineau Channel.

Powerhouse Number 1 was destroyed by fire in 1923, and rebuilt and brought back on-line by 1935.

During the summer of 1967, a rehabilitation of the Salmon Creek Dam was finished. This work involved re-grouting the dam, removal of deteriorated concrete and an application of a layer of high strength material to the upper 45 feet of the upstream face of the dam.

Age caught up with the lower powerhouse.  In December 1974, the plant was shut down due to the high cost to rebuild the generators. Ten years later, however, a new lower powerhouse was constructed adjacent to the old one to take its place. This new plant generates 29.5 GWh of energy annually.

The upper power house was taken out of service in 1998.

Today, the Salmon Creek Dam still plays an important role in Juneau. Not only does it generate over 10% of Juneau's power, but it also supplies water to the community and is the sole source of water for the Douglas Island Pink and Chum Hatchery at Lower Salmon.

Annex Creek Hydro Project (return to top)

The site for the Annex Creek Power House was developed in 1915. Annex Creek Lake, a 264-acre lake about 800 feet above sea level, formed a natural reservoir which Bart Thane and his Alaska Gastineau engineers realized could be tapped by constructing a concrete tunnel out of the lake at a depth of 150 feet. Water could then flow, via the tunnel, to a power house without the necessity of constructing a major dam.

Wasting no time, construction on the project began almost immediately, and in a feat that is said to be unique in the history of hydro power development, Upper Annex Lake was tapped under a hydraulic head of 150 feet without the loss of any water from Annex Lake.

The whole project was constructed entirely within seven months of its conception, and its powerhouse was soon sending back much needed electricity to the mines. Unfortunately, however, transmission line failures took this plant off-line frequently in its early years.

The troublesome Annex Creek transmission line was built in 1915. Alaska Gastineau Chief Engineer Harry L. Wollenberg, its designer, considered the Annex Creek line to be very well designed prior to its construction.

In letters to Bart Thane, Wollenberg described how carefully the route of the line had been chosen, how the danger of snow slides could be avoided, and how the line would run parallel to the strong prevailing winds. In fact, Wollenberg was so confident that his design would be more than adequate that he wrote:

" does not seem justifiable to overdesign it to any great extent...while higher test insulators and heavier towers might give some more insurance against interruptions, it is the opinion of the writer that the equipment outlined above is all that any known conditions require and if we tried to design for unknown conditions of greater assumed severity, we would soon have an investment out of proportions to the results obtained."

These were words that would come back to haunt Wollenberg a year after the line was completed.

In the period from November 1 to December 11, 1916, Annex Creek was off-line 100 hours due to transmission line breaks. Heavy sleet and snow broke the line for long distances.

Between December 11 and December 18, the situation worsened and tragedy struck: a repairman, trying to get to a broken line, was killed by a snow slide. Conditions were so bad during that week that the line was only in service for 13.5 hours. Finally, in January of 1917, a snow slide destroyed six of the steel towers holding the line up.

In a few short months, devastation to the line proved how harsh the conditions under which it had to operate really were.

Later, needed modifications were made to the line. Steel high strength conductor was used in the area of the harsh conditions. This high resistance conductor generates enough heat to melt snow and sleet off the line instead of freezing it. In the past, it frequently was the weight of frozen sleet and snow which caused the line to fail.

The Annex Creek Plant has been manned for most of its life, but the project was automated for remote, unmanned operation in 1977, and a single watchman/operator began staying on site five days a week in 1988. Even with all the new automated equipment and technical upgrades of existing equipment, the original turbines and generators remain in place providing reliable power to Juneau.

This facility still provides power to Juneau today. The Annex Creek Plant's average annual production of electrical energy is about 26 GWH, about 10% of the CBJ's annual power needs.

Lemon Creek Fossil Plant (return to top)

This is the site that AEL&P received from the Federal Government in 1966 as partial payment for AEL&P's pole yard.  

Three Electro Motive Division (EMD) diesel engines were installed at Lemon Creek in the late 1960's and early 1970's. And in response to rapid electrical load growth in the early 1980's, AEL&P installed six additional EMD diesel engines and two gas turbines, bringing its capacity at Lemon Creek to 57.5 MW.

Lemon Creek now functions only as a backup of the Snettisham Hydroelectric Project. It is brought on-line quickly during a Snettisham outage and is used until Snettisham can be brought back on-line again.

Auke Bay Fossil Plant (return to top)

In November 1989, with the merger of Glacier Highway Electric Association into AEL&P, the company acquired the Auke Bay GHEA EMD diesel engine and site. The Solar Centaur Gas Turbine had been leased and used by GHEA. The turbine was not acquired at the time of the merger but has since been purchased and was reinstalled. This capacity was added to the AEL&P power generation grid. It runs on either diesel or natural gas and is part of the backup generation system that comes on line during a Snettisham outage.

Snettisham Hydroelectric Project (return to top)

The Federal Government's Snettisham Hydroelectric Project came on-line on December 1, 1973, offering 47.2 MW of electrical power to the Juneau power grid. Its hydroelectric potential had been discovered early in this century by people exploring for minerals and timber south of Juneau across Taku Inlet.

With the growth of Juneau and the forecasted need for more capacity, detailed feasibility studies concerning the development of Snettisham as a hydroelectric project were commissioned and conducted in the 1950's. Based on favorable reports, construction of the project was authorized by Congress in 1962, and actual construction of the project began in 1967.

Upon completion the plant was put on-line. The 44-mile long transmission line, however, followed a route very similar to the Annex Creek Line's original route over Salisbury Ridge. Soon history was repeating itself. The Snettisham line suffered frequent problems as it crossed over Salisbury Ridge, and, as a consequence, the supply of power from Snettisham to Juneau was frequently interrupted for long periods during the first two years of its operation.

With constant outages and frustrated customers, the Alaska Power Administration, the Federal agency in charge of the project, decided to move parts of the transmission line to reduce the line failures. Through the Corps of Engineers, the work was contracted out and the line relocation was completed in September 1976. Since that time, service from Snettisham has been excellent, with few outages from failed transmission lines.

The Snettisham Project has had two stages. The first, the Long Lake Stage, was the primary project to develop the hydro potential of Snettisham for Juneau. Capable of producing 47.2 MW, the Long Lake Stage's yearly average energy output is over 200 million KWH.

The second stage, the Crater Lake Stage, was completed in 1990. The Crater Lake Stage, like the Annex Creek Project, consists of a tunnel from Crater Lake to the Snettisham power plant, with another generating unit added to take advantage of the additional water flow. This stage was part of the overall original project design, but plans called for it to be constructed only when the energy was needed. With the addition of the Crater Lake Stage's 31 MW capacity, the total amount of electrical energy now available from Snettisham is 78.2 MW.

The Snettisham Project was designed to provide the Juneau power grid with plentiful power for the long term. Snettisham's power plant and generating facility is at sea level and in the mountain itself, with other supporting building and shed's outside the portals. Water from the generators help support the Snettisham Fish Hatchery that is run year 'round by the State. In addition to Snettisham's Long and Crater Lakes, there are other nearby projects that are available for development when the additional energy is needed by Juneau. These projects have a projected service life of at least 100 years, making hydro power a continued part of life in Juneau for many years to come.

A.J. Steam Plant (return to top)

The A.J. Steam Plant was built on the shore of Gastineau Channel in Juneau in 1916 as an 8,000 KW plant. It was built by the Alaska Juneau Gold Mining Company to supply power to the mill that it was building.

The steam plant generators were removed many years ago, and in the early 70s, after AEL&P purchased the A.J., the building was converted to the AEL&P warehouse.

The Treadwell Ditch (return to top)

Construction on the Treadwell Ditch, as this hydro project was called, began in 1882, and the project was completed in 1890. Used to power the Treadwell Mines' stamp mill, the ditch started at the 950-foot level on Douglas Island at Fish Creek. The ditch then wrapped around the outside of the mountains, following their contours until it reached the Treadwell Mines south of Douglas. Along the way to the mines, the ditch intersected with several creeks and picked up additional water from each one. This plant was taken out of service many years ago.

Sheep and Nugget Creeks (return to top)

These plants are no longer in operation today. Their facilities are in an extreme state of disrepair and exist only as artifacts of the Treadwell mining complex. They are, however, historically significant and worth noting.

In 1910 Treadwell constructed the Sheep Creek Power Plant. This plant was seasonal, like Gold Creek, depending entirely on the natural flow of the water coming down Sheep Creek. Both the plant and its water flume were constructed in the same year. When the water was flowing adequately, it was possible to generate 2,225 KW at this plant.

Sheep Creek is about four miles south of Juneau and the Treadwell mines were on Douglas Island. To transmit the power to the mines, a line was strung from Sheep Creek to the site where the present Juneau-Douglas bridge now stands. There the line crossed Gastineau Channel to Douglas Island and turned south to the Treadwell mines.

Construction on the Nugget Creek Hydro Project began in 1912, and the powerhouse flume and a 6,900-foot pipeline for it were completed in 1914. Another "run-of-the-river" plant, the powerhouse was located at what was then the foot of Mendenhall Glacier; Mendenhall Glacier has since receded considerably. When the flow of Nugget Creek was optimal, the Nugget Creek powerhouse could generate 2,300 KW. A transmission line to the Treadwell mines was strung to the point where the Sheep Creek line crossed Gastineau Channel, where it, too, crossed the Channel and turned south. This line is used today only to provide power to the Mendenhall Visitors Center.

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