Chelan 1
Jordan Bakken
Sec: 22
Final Paper
Project Area:
This paper will explore and discuss geologic features of Lake Chelan in Manson, WA. The
lake is noticed for its steep hills, very deep depth of over 1500 feet and the clarity of the water.
The lake has a length of 20 miles long and it drains into the Columbia River before it flows
through a dam. Lake Chelan is located in central Washington right at the eastern base of the
eroding Cascade mountain range. The water is extremely cold and lacks turbidity because of its
short distance from where it melted preventing any aquatic plant growth at the bottom of the
lake keeping the water clear enough to see the bottom of the lake 50 feet off shore. The lack of
aquatic plant life makes it an extremely harsh environment for fish to live in because of the lack
of food supply. Sturgeon, carp and other bottom feeder fish are the common fish that reside in
the lake, some growing over 12 feet long. The town of Manson sits on the South side of the lake
where a dam was built to help irrigate the orchard crops and produce small amounts of
electricity. The drinking water in the town of Manson comes directly out of the lake from
hydraulic pumps that suck water right from the bottom of the lake. Rapid uplift from the
cascades gives the lake its steep slopes. The depth of the lake came from a large glacier over
17,000 years ago that cut through the rock creating a deep reservoir for glacier melt to fill up
creating a lake. The primary geologic structures present are mounds of dirt and other gneiss
that is erosion from the Cascades.
Chelan 2
Rocks Present:
The small town of Manson in Lake Chelan WA does not contain many visible exposed
rock structures because of the amount of bedded sediment from glacial erosion [Chelan 2013].
The major rock in the Chelan area is Gneiss with some exposed structures, mostly composed of
granitic and basalt (Fig.1). Metamorphic gneiss is the primary visible exposed rock where you
will find right off State Route 150.
When roads were built, the gneiss
was cut or blasted if it was found in
the way, leaving behind the
exposed internal rock formations.
Fig. 2 shows intrusions of
fractured basalt.
These cuts from the road
Fig. 1 shows grains of sediments bonded together forming
the metamorphic rock Gneiss.
construction shows faults and veins
of basalt formed from underground fissures that lacked the pressure to breach the crusts
surface (Figure 2). The lake body was formed over millions of
years from the build-up of the cascades with the combination of
glacial erosion. The 50 mile lake has a depth of over 1,500 feet,
with its widest point measuring over 2 miles lined with sediments
from the last glacial erosion over 17,000 years ago to the
sediments that are left behind today [Chelan 2013]. At the lakes
edge, only sand and water is found. The water in the lake is too
Chelan 3
turbid and lacks enough adequate nutrients to support major aquatic plant and biological life.
The freezing temperatures of the lake from glacial runoff is also a variable with the lakes lack of
life.
Structures present:
The major structure present in Chelan is the beginning to the Cascade Mountains. Tall
and very steep hills surround all sides of the lake except the south eastern end where the water
flows out (fig. 3). The
Town of Manson resides
on the collected
alluvial plains left by the
last glacier deposits.
On the south-eastern side
of the lake a large
collected deposit of
sediment left by the
most recent glacier has
created a small
peninsula named Wapato
Point, where
condominiums and hotels
for tourists have been
built up [NPS 2013]. The
composition of Wapato
contains larger and
coarser sediments of
parts of granite that has
Fig. 3 steep hills from the Cascades allows
gravity to transport sediments directly to the
bottom of the lake.
gneiss with some smaller
been rounded from the
lakes shore line. The hills to the east side to the lake are much smaller and lose intensity from
erosion and a further distance from the Cascades. Glacial abrasion of ice and rock has left the
pointed hills with a layer of dirt leaving the hills with a series of arêtes and smaller cirques that
fill with fresh water in the spring. The larger valleys have a wide U shape that was carved out by
Chelan 4
a large glacier leaving the hills with a more gradual incline allowing more trees and shrubs to
grow much denser.
The reasoning behind the lakes temperature is the lack of time the water has traveled as a
liquid from its original frozen solid state as ice as well as its turbidity and lack of dissolved
nutrients (Fig. 5). Because the water has not traveled far and has not had time to warm up form
solar heat, it stays just above freezing
and doesn’t allow many organisms to
live.
Geologic History:
The lake resides directly above the
Fig. 4 shows the sand
structures on Wapato Point.
Fig. 5 shows ice and snow melt off the
hills and flow directly into the lake
where the water sits.
Juan de Fuca plate which is converging into the NorthAmerican plate creating the Cascade Mountain Range.
The sediments from the metamorphic rocks in the lake came from the bottom of the ocean
millions of years ago when sediments conglomerated under tremendous amounts of pressure
and heat. When sediments are turned to magma again if they are too hot, rising to the surface
but cooling down before it breaks the surface, the structures left behind are large protruding
boulders of granite and basalt most containing cracks or faults of some type that are mostly
found off the high way where the rock has been blasted away to construct the roads. The depth
of the lake is slowly becoming shallower as more sediments from the Cascades weather and
Chelan 5
erode filling the lake bottom with sediment (Fig. 4). Lake Chelan acts as a natural catch basin for
the Columbia River, collecting a large mass of water that will eventually flow into the Columbia
River. Over time the potential for the lake to fill with
sediment will become more likely, leaving orchard farmers
with no water to irrigate crops. The water in the lake is very
clear, leaving the lake bottom visible up to 50ft deep.
While walking up and down Lake Chelan,
different rocks and structures become visible. The
Fig. 6 shows the South East section of
the like with shallower hills.
further Northwest you go, the steeper and
greener the mountains become while on the
Southeast end the terrain gets flatter as it
gets further from the cascades and closer to
the Columbia River (Fig. 6). The south side of
the lake is where more of the orchard fields
are found because of the irrigation canal that
is fed by the lake. The land here is not as steep and contains a lot more sediment and lacks
greener vegetation [Mehaffey 2013].
Water Resources: Water supply and pollution
The climate in Lake Chelan during the summer is very hot and dry with little
precipitation but during the summer the weather rehydrates the dry soil with snow and ice
pack. According to the Western Regional Climate Center the lake averages an annual
Chelan 6
precipitation of 10.98 in/y [western 2013]. Highest maximum average monthly temperature for
the month of July in 85.3 degrees Fahrenheit while the lowest average temperatures are
recorded at -18 degrees Fahrenheit. During the snowy seasons, the hills surrounding the lake
average 8ft of snow during the month of January. The lake is extremely deep with steep slopes
which was formed from a giant cut in the crust caused by a glacier that crawled up the steep
slopes of the Cascades over 17,000 years ago which is responsible for giving the hills their
drastic formations[Chelan 2013]. The height of the Cascades disperse the concentrated clouds
that come from the Pacific Ocean. The surface of the land heats up due to more solar
penetration from the sun which causes the clouds that do make it over the Cascades to rise up
higher into the atmosphere.
The Lake itself is a runoff of the glaciers from the Eastern face of the cascades, feeding
into the Columbia River right before it passes through the Lake Chelan dam. The water is
extremely cold and lacks nutrients which prevents plant growth in the lake keeping it crystal
clear and freezing cold. The flow of the river is perennial but the shore line of the lake is
intermittent because of the flow control caused by the dam. Because of the lack of distance of
the lake water from the melting glacier, the water remains frigid cold all year long, even with
limited rain and heat up to 85 degrees Fahrenheit. The sediments in the lake are extremely fine
because of the amount of time the Cascades have been rapidly uplifting and eroding the
surface materials. According to the Lake Chelan Reclamation District (LCRD), the irrigation,
wastewater and drinking water all are directly pumped out of the lake [Lake 2013]. There are 2
pumps in the Manson bay that pump directly to the water treatment facility plant and then
redirected to either house use or irrigation.
Chelan 7
Conclusion:
With the town and the primary orchard farms are on the East side of the lake,
preventing any possible threats of a catastrophic mudslide or rock fall. The primary issue
farmer’s face is the erosion of the crop fields caused by wind which carries nutrient rich soil to
other farms, losing the ability to provide a good yield for the year. Farmers try to prevent
erosion by planting grass or shrubs in between the orchards keeping the soil packed from rootlock. With the Cascades preventing any cloud cover from building up, the lake does not
experience very much rain in the hot seasons, preventing crops from growing naturally and
requiring water to be channeled to the farms for irrigation. Apple orchards in Washington are
slowly becoming obsolete as farmers are switching to grapes for their cash crops. The benefit to
growing grapes is grape vines require lots of dry air and sunlight but need minimal amounts of
water to survive. The Lake Chelan dam was built to help channel water to the large residential
and tourist population because of the recent rapid growth in Manson.
Chelan 8
Works Cited
"Chelan Fresh Marketing - Lake Chelan." Chelan Fresh Marketing - Home. N.p., n.d. Web. 19
Mar. 2013. <http://www.chelanfresh.com/lake-chelan/>.
"Lake Chelan." Relcamation District. N.p., 8 Jan. 2013. Web. 2 Apr. 2013. <http://lcrd.org/>.
"Western Regional Climate Center." Western Regional Climate Center. N.p., n.d. Web. 3 Apr.
2013. <http://www.wrcc.dri.edu/>.
Mehaffey, K.C.. "Lake Chelan is unique." The Wenatchee World 8 Mar. 2013: n. pag. Wenatchee
World. Web. 18 Mar. 2013.
"NPS: Nature & Science» Geology Resources Division." nature.nps.gov » Explore Nature.
N.p., n.d. Web. 19 Mar. 2013. <http://www.nature.nps.gov/geology/parks/noca/>.
Map
"USGS." Geological map of Chelan. N.p., n.d. Web. 18 Mar. 2013.
<pubs.usgs.gov/imap/i1661/http://>.