Download - Elwha Dam Project
-
8/8/2019 Elwha Dam Project
1/1
During phase one, all four spillway gates
on the south side will open, allowing
water in Lake Aldwell reservoir to drop
18 feet.
Phase two
involves removing
the south gates
and digging a
diversion channel.The blasting a
large plug of
bedrock to reroute
the river through
the gap.
Phase three
takes out the
north spillway
and upper
portion fo the
dam and installs
a road in order
to accesss the
penstock tubes.
1.
2.
Phase 4 will
remove the steel
penstocks, the
concrete intake
structure and the
powerhouse.
4.
3.
Phase ve
involves
removing
200,000 cubic
yards of rock,
concrete and r
trees behind the
dam.
Phase six
involves
removing
the
concrete
dam using
explosives.
6.
5.
Lake Aldwell
South Gates
Left Spillway
Original Channel
Large Penstock
Surge Tower
Small Penstock
Powerhouse
Elwha Dam
Glines Canyon Dam
Lake Aldwell
Lake Mills
Lake Crescent
Strait of Juan de Fuca
Elwha River
P O R T A N G E L E S
Da Prjct | Removal of two dams on the Elwha River is the second largest ecosystem restorationproject in the National Park System behind efforts to restore the Everglades National Park in Florida..
A Pa t Rstr Sa, Stad ad Trt
Here are the restoration strategies for various populations, as laid out in Elwha Fish Restoration Plan:
Chinook
Coho
Pink
Bull TRouT
SoCkeye
Chum
STeelheADChinook salmon in the Elwha historically included a stock that re-
turned in the spring and one that returned in summer or fall. To-
day, the chinook run is considered a composite of hatchery and
wild genes, mostly from the Elwha. In addition to natural spawn-
ing, the restoration strategy calls for hatchery production of this
composite stock with normal release into the Elwha after hatch-
ing. Other chinook will be held and grown for a year before re-
lease. Biologists believe that over time the population may sort
itself into groups returning at different times. In addition, a re-
serve population will be reared in a facility on nearby Morse
Creek to ensure that Elwha chinook genes survive.
Two winter steelhead populations have been identified: an ear-
ly run associated with a hatchery stock from outside the Elwha
and a late run derived from the native stock. In some years, the
native stock has been as low as 60 or 70 fish.Strategies are fo-
cused on the native stock. In addition to natural spawning, they
include growing steelhead eggs and fry to adults in a captive
broodstock program, designed to boost the numbers while be-
ing careful about inbreeding. Other strategies include releasing
year-old fish at downstream stations and releasing a variety of
ages at upstream locations. Production of the early, nonnative
stock will continue for now at low numbers. If a summer steel-head population exists, the numbers are critically low.
Elwha River coho are believed to be a native stock heavily influ-
enced by hatchery production. The strategy is to rear them for
a year in the hatchery before release. As the numbers build up,they may be released at a younger age in the upper river or even
planted as eggs.
Historically, pinks may have been the most abundant salmon in
the watershed, but today they are at critically low levels, worse
off even than the chum. It is believed that before the damswere built pinks went all the way to Lake Mills. Today, they cant
find the right size of gravel below the dams but that should
change when gravel begins to move downstream during demo-
lition. In addition to natural colonization, restoration strategies
may include a captive broodstock program or simply distributing
fry and eggs to various upstream locations.
Historically, two runs of Elwha chum probably existed, accord-
ing to genetic studies. Both are considered at critical levels. Their
numbers are being boosted by capturing and spawning adults,then outplanting their fry and eggs at various locations in the
river.
Sockeye salmon, which once returned to Lake Sutherland, are
considered extinct because the Elwha Dam blocked their return
from the ocean to the lake. Kokanee, which are essentially resi-dent sockeye, still live in the lake. The restoration strategy is to
see if some of the offspring from residents become anadromous
(migrating) once they are free to leave the lake. Otherwise, non-
native sockeye from other areas may find their way into the lake.
Two stocks of bull trout have been identified above the dams.
The strategy is to leave them as unmolested as possible during
dam removal. Bull trout will be captured in Lake Mills before
dam removal and moved upstream. During dam removal, trout
in the middle stretches may take refuge in the smaller tributary
streams, which is why efforts are being made to remove obsta-
cles. One example is the replacement of a 5-foot culvert on Griff
Creek with a 26-foot bottomless arch culvert. Once the dams areremoved, bull trout are expected to benefit from a greater range
of movement as well as access to salmon fry, which they will eat.
Bull trout, like chinook and steelhead, are listed as threatened
species under the Endangered Species Act.
graphics by J.D.Williams