|QUICK SEARCH: FISH
BYPASS || POWERHOUSE
REHABILITATION || HYDRO PROJECT
BACKGROUND || GEOLOGY || WATERSHED || RIVER FLOW || RESERVOIR
CONSTRUCTION || DEVELOPMENT HISTORY || CONSTRUCTION COSTS || POWER SALES CONTRACTS || PROJECT LICENSE || GENERATORS || TURBINES
GATES || TRANSMISSION
Rocky Reach Hydro Project is located in north central Washington
state on the Columbia River, about seven miles upstream from the
city of Wenatchee. By river, the dam is 215 miles below the
Canadian border, and 473 miles above the mouth of the Columbia
at Astoria, Ore.
More than 7 million people throughout the Northwest benefit from
clean, renewable energy produced at Rocky Reach. The project is
also nationally recognized for efforts to protect the environment.
A first-of-its-kind juvenile fish bypass system was completed in
2003 to help young salmon and steelhead on their way to the ocean.
A major powerhouse upgrade started in 1995 includes new turbines
that are more fish friendly. Improvements to turbines and
generators are also designed to improve efficiency and
FISH BYPASS SYSTEM
An innovative juvenile fish bypass
system helps move young salmon and steelhead
quickly and safely past the Rocky Reach Hydro Project.
The bypass includes two main parts. The
first is a collector system which relies on 29 large pumps to create a
strong current, appealing to the natural instincts of the young fish
to attract them to a collector in the damís forebay.
The bypass pipe traverses the
Once the fish are in the collector,
water moves them into the second part of the system -- a steel tube up
to 9 feet in diameter. The tube passes through the dam and extends
4,600 feet around the back side of the powerhouse, across the face of
the spillway and about one-third mile down the east side of the
Columbia River before the fish are returned to the river. The entire
trip will take young fish about six to eight minutes.
Construction of the pipe
continued on the east bank of the river.
Construction of the permanent system
was carefully planned so that all work in the river would be done
between fish migrations. Some of the large components of the collector
system, including the pump house, were built at a peninsula upriver
from the dam during the summer, and then floated into place once
salmon migrations were finished.
Original CAD diagram provides an
overview of the Rocky Reach fish bypass system including pump station
(left, in forebay) and fish return pipe (lower, right).
In addition to making the down-river
trip easier for juvenile salmon and steelhead, the bypass system will
also reduce the need to spill water over the dam. That water can then
be used to generate electricity more than offsetting the $112 million
cost of the bypass. During a 15-year life span, the project is
expected to save spill worth about $400 million.
Since 1985, the PUD has developed laboratory models and tested
prototype fish bypass systems for intercepting and moving juvenile
fish around Rocky Reach as they travel downriver to the ocean. Screens
were designed to steer young salmon and steelhead away from the
turbines and into a bypass channel. None of the prototype screening
systems tested achieved the results experienced at other Columbia
River hydro projects. So a new approach was taken in 1995 -- a surface
bypass and collection system that appeals to the young fish's natural
instinct to migrate downriver near the surface, following the water
flow. This differs from conventional turbine intake screens, which
require fish to dive into the turbine intakes before they are
intercepted by the screens. Also, after the surface collector was
added in 1995, the fish guidance effectiveness improved for the screen
systems left in two units to enhance interim protection.
Because of the improvement in the screens' performance, they have been
incorporated into the final design of the fish bypass system.
studies determined that fish generally travel in the upper 60 feet of
the river. The prototype was designed to use natural and
turbine-induced surface currents in the upper 60 feet of the flow to
give fish an alternative to diving into the turbine intakes --
entering the bypass system instead. Attractive features of this
concept include the minimal volume of flow that's lost, minimizing
power losses, as well as the relatively low installation cost.
through the bypass pipe were occasionally diverted to an evaluation
facility, where the juvenile fish were examined to identify species
and condition. A 24-hour videotaping system counted the number of fish
using the bypass system.
the collector's effectiveness in moving fish, a few of the young
salmon and steelhead were implanted with electronic tags and released
upstream of the hydro project during the spring and summer testing
period. The movements of other test fish outfitted with acoustic tags
were monitored as they moved through the forebay to determine how they
reacted to the surface collector. These studies allowed biologists to
view 3-dimensional movement of fish in the forebay as they approached
the fish bypass system and dam. This technique was used for this
reason first at Rocky Reach.
prototype surface collection system was modified each year, based upon
test results from the previous year. Increased flows into and through
the collector, plus improvements to the diversion screen/gatewell
collection system in certain units, provided very encouraging
study results in 1997. A second
entrance was added to the surface collector in 1998, but results in
attracting fish were not as good as anticipated. So in 1999, the
second entrance to the surface collector was modified to allow
biologists to vary the entrance width from a minimum of 22 feet to a
maximum of 44 feet. This allowed biologists to analyze how water flows
affected, and which water flows were better at attracting fish.
FISH SURVIVAL STUDIES
Since 1998, the PUD has been
involved in studies that attempt to estimate the survival rates of
juvenile salmon and steelhead as they migrate past our hydroelectric
projects. It is important that biologists get these estimates to
ensure the PUD is meeting its obligations under the Habitat
Conservation Plan. The PUD has been in the forefront in developing new
technologies to estimate survival.
Studies designed to estimate the
survival of downstream migrating juvenile chinook salmon have been
conducted at the Rock Island Hydro Project each spring since 1998.
These studies, using PIT-tag technology, entailed tagging and
releasing hatchery chinook salmon in the tailraces of both Rocky Reach
and Rock Island dams.
Since 2002,the District has also
conducted studies to evaluate the use of acoustic tag technology in
estimating fish survival. These studies involved surgically tagging
and releasing hatchery chinook salmon in the tailrace of Rocky Reach
Dam. The results of this study were encouraging; detection rates were
high, and the operational life of the tags was sufficient to estimate
survival using acoustic tags in future years.
A fish ladder was
placed at the Rocky Reach Hydro Project when the dam was built in
1962. The ladder consists of a series of 100 pools of falling water,
each one foot above the other. Adult fish heading upstream are
attracted to the ladder by a collection system with entrances located
at the base of the spillway, the center dam, and along the downstream
face of the powerhouse. Fish ladders at both hydro projects are well
used by adult salmon and steelhead migrating upriver. Studies of
upriver migration confirm that our hydro projects do not delay the
return trip of adult salmon to their spawning grounds.
The District is in the midst of a major upgrade of the powerhouse.
1995, the District installed new adjustable-blade turbine
runners on all 11 generating units. The District is also
rehabilitating generators on all the units. The work will improve the efficiency and reliability of the hydro
plant. The end result will be more power generation, higher revenues
and lower maintenance costs. In addition, the new turbine runners are
"fish friendly," designed to reduce juvenile salmon and steelhead
The Rocky Reach site has long been recognized for its hydroelectric
potential. The U.S. Army Corps of Engineers first considered the site
in its 1934 "308 Report." In the 1950s, the site became the
focus of extensive studies by the PUD. Geological contour maps were
studied, construction costs were estimated, and lengthy computations
on such things as the forces and stresses a dam would have on the
surrounding area were made.
The original site
selected for the Rocky Reach Project by the U.S. Army Corps of
Engineers was about one mile upriver from where the dam is today. The
present site was found to have superior rock for anchoring the dam,
and the river channel is narrower at that location.
Rocky Reach Dam is constructed on metamorphic bedrock formed millions
of years ago through compaction of sedimentary materials under extreme
pressures and temperatures. The rock provides a very stable foundation
for the structure, which meets or exceeds all Federal Energy
Regulatory Commission engineering safety and stability criteria.
Examples of the bedrock are displayed at the Project's Visitor Center.
The watershed lies east of the Cascade Mountains and west of the Rocky
Mountains, consisting of parts of Washington, Idaho, Montana, and
British Columbia. The watershed encompasses about 90,000 square miles.
The regulated flow of the Columbia River at the Rocky Reach Project
varies on an average annual basis between 40,000 cubic feet per second
(cfs) and 220,000 cfs The average annual flow over the past 30 years
has been 115,000 cfs That's enough flow to cover a standard-size
football field with water 144 feet deep in just one minute. The
maximum and minimum recorded natural flows are 530,000 cfs on June 10,
1961, and 25,000 cfs on November 11, 1974. The largest known flood
happened on June 7, 1894, with an estimated peak streamflow of 800,000
cfs in the Wenatchee reach of the Columbia River.
Lake Entiat, the Rocky Reach Project reservoir, extends upriver about
43 miles and has a surface area of some 98,000 acres. The reservoir
contains 35,000 acre feet of usable storage with a 4-foot drawdown. The
average annual minimum water temperature of 37 degrees Fahrenheit
normally occurs in February. The average annual maximum water
temperature of 65 degrees Fahrenheit usually occurs in August and
The Rocky Reach Project was developed over a period of about 15 years.
Construction of the dam and original powerhouse with seven generating
units began in 1956 for the purpose of power production and flood
control. The addition of four more units began in 1969 after
ratification of the Columbia River Treaty between the United States
and Canada. The additional units were installed primarily to make use
of stored water released from reservoirs in Canada and the Libby Dam
reservoir in Montana.
The District received a preliminary permit for the Project from the
Federal Power Commission (FPC) on August 10, 1954. An application to
construct and operate the dam was filed with the same agency on
January 13, 1956. The Federal Power Commission issued a license to
build the Project six months later, on July 12, 1956. Construction of
the dam and original powerhouse began on October 2, 1956 under the
supervision of the District's engineering design firm, Stone and
Webster Engineering Corporation. The immediate task was the
installation of cofferdams to seal off the area designated for the
spillway from the river flow during low water.
construction, the powerhouse was built. A total of 3.3 million cubic
yards of dirt and rock were moved during the five-year initial
construction. Employment peaked at 2,184 in July 1959. The initial
seven generating units were placed in commercial operation on November
1, 1961, six months ahead of schedule. On September 1, 1966, the
District filed an application with the Federal Power Commission to
amend the Project License to add four generating units. The FPC issued
the license amendment May 23, 1968. The second phase of construction
began April 22, 1969, and was completed December 1, 1971. The
expansion work increased the power plant's generating capability by
60%, from 815,000 kilowatts to 1.287 million kilowatts.
The Project was financed through the sale of revenue bonds. A revenue
bond is a pledge of future revenues generated by the project to repay
debt. No tax money was used. The original project, which cost $273.1
million, was financed with a $23.1 million bond issue completed in
November 1956 to allow for an early construction start. It was
followed by a completion bond issue of $250 million in January 1958.
Included in the Project
costs were the relocation of a rail line, highways, land acquisition,
relocation of the Town of Entiat, and financing. The subsequent
powerhouse expansion and addition of four generating units completed
in 1971 were financed by a revenue bond issue of $40 million, sold in
Repayment of the revenue bonds is guaranteed through power sales
contracts between the Chelan County Public Utility District and the
purchasers of Rocky Reach power: PacifiCorp, Portland General Electric
Company, Puget Sound Energy, Avista Corp., the Aluminum Company of
America (ALCOA) which has a plant just south of Wenatchee, and the
District's Electric Distribution System. Each of the contracts covers
a period extending 50 years after the November 1961 starting date of
commercial operation for the initial seven generating units, or until
final payment is made on the $273 million in bonds sold for the
initial phase of the Project, whichever is longer. The contracts
expire in November 2011.
The original Project License was issued July 11, 1957 by the Federal
Power Commission. The license expires in 2006. Prior to that, the
District will be required to submit an application for renewal.
SEE ALSO: RELICENSING
The generator is the part of the unit where electricity is produced.
As water flow turns the turbine blades, hydraulic energy in the form
of the weight and pressure (head) of the moving water is converted to
mechanical energy. A huge steel shaft connects the turbine to the
generator, where the mechanical energy is converted to electrical
The hydraulic turbines consist of huge water wheels that
resemble ship propellers. They are turned by the water flow and
connected to the electricity-producing generators by large steel
shafts. All 11 units at the Rocky Reach Project are
equipped with adjustable blade turbines. Their design allows the turbines to maintain
maximum operating capacity and efficiency despite variations in
the river flow and generator output.
The crest of the reservoir can be regulated by 12 spillway gates,
which open individually and allow water to pass through separate
spillway bays. The gates pass water seasonally that is surplus to
power generation needs, or as required for assisting fish in their
Power from the Rocky Reach Project is delivered to
the District's Distribution System at 115,000 volts. Other
230,000-volt transmission lines deliver energy to the Project's power
purchasers. Power also flows into the regional grid of
the Bonneville Power Administration.
TOP OF PAGE