Cowlitz River

from Wikipedia, the free encyclopedia
Cowlitz River
The Cowlitz River catchment area

The Cowlitz River catchment area

Data
Water code US :  1518230
location Lewis County in Washington (USA)
River system Columbia River
source Near Laurel Hill on the southern edge of Mt. Rainier National Park
46 ° 40 ′ 40 ″  N , 121 ° 35 ′ 6 ″  W
Source height 363  m
muzzle at Longview in the Columbia River Coordinates: 46 ° 5 '55 "  N , 122 ° 54' 40"  W 46 ° 5 '55 "  N , 122 ° 54' 40"  W.
Mouth height 0  m
Height difference 363 m
Bottom slope 2.1 ‰
length 170 km
Catchment area 6400 km²
Drain MQ
 259 m³ / s
Left tributaries Cispus River , Toutle River
Right tributaries Tilton River
Reservoirs flowed through Lake Scanewa, Reef Lake, Mayfield Lake, Packwood Lake
Medium-sized cities Longview
Small towns Kelso

The Cowlitz River is a 170 km long tributary of the Columbia River in Washington state . With its tributaries, the Cowlitz River drains most of Mount Rainier , Mount Adams and Mount St. Helens . Its catchment area is in Lewis County between the Cascade Range and the cities of Kelso and Longview . It covers 6400 square kilometers.

The main tributaries of the Cowlitz River are the Cispus River and Toutle River . The latter was blocked by lahars when Mount St. Helens erupted in 1980 .

bridges

The Cowlitz River is spanned by several bridge structures. Directly above the confluence with the Columbia River, a railway bridge connects Longview Harbor with the Burlington Northern and Santa Fe Railway (BNSF), a road bridge is next to it. A little further up, two bridges connect West Kelso with the rest of Kelso and north of Kelso a railway bridge for the Columbia and Cowlitz Railway crosses the river.

At Lexington, a two-lane bridge connects SR 411 with ramp 42 of Interstate 5 on the east bank. In Castle Rock , a bridge leads from the city center to the school and residential areas on the other side of the river and a few kilometers further, just above the confluence of the Toutle River, the BNSF railway line crosses the river. Interstate 5 crosses the river between Vader in Lewis County and Toledo in Cowlitz County and the SR-505 crosses the water at Toledo.

The US Highway 12 leading west of Mossyrock over the Mayfield Lake. A road was built on both sides towards the opposite bank, which is connected in the middle by a bridge section. At the dam, a small bridge on the SR 122 connects both banks. East of Mossyrock, the Cowlitz River Bridge was the longest concrete arch bridge in North America with a length of 168 m until 1971 .

At the head of Reef Lake, a road bridge connects the wooded areas south of the river with Morton and Glenoma on the north side. At Randle the river crosses the SR 131 and thus opens up the area on the Cispus River and the northern areas of the Mount St. Helens National Volcanic Monument . US Highway 12 crosses the river again in Cora and then in the Big Bottom Valley between Randle and Packwood. Above Packwood, numerous forest trails cross the headwaters of the Cowlitz River.

Reservoirs

The Cowlitz River has three large hydroelectric dams and a number of smaller power plants.

The Cowlitz Falls Project is a 70 megawatt power plant that was built in the early 1990s and completed in 1994. The dam is almost 43 m high and 213.5 long. The power plant generates 260 gigawatt hours of electricity annually. The reservoir is located below Randle at the mouth of the Cispus River.

The Mossyrock Dam began generating electricity for Tacoma City Light in 1968. The dam has a height of 184.5 m and damms the 37 km long Reef Lake. This was formerly known as the Davisson Reservoir. The structure is the tallest dam in the Pacific Northwest . The dam takes its name from the neighboring town of Mossyrock and the lake bears the name of the place Riffe, which went down together with Kosmos when the reservoir flooded.

Mayfield Dam is 259 m long and 56 m high. A 262 m long tunnel connects the reservoir with the turbine house . This is where power generation began in 1963. Mayfield Lake offers numerous recreational opportunities as there are several park facilities on its banks and is attractive due to its location a few kilometers below Mossyrock. The regulated inflow from the Riffe Lake allows the water level of the Mayfield Lake to fluctuate very little.

Packwood Lake was created in 1964 by a dam on the Washington Public Power Supply System (now Energy Northwest ). The actual task of this dam is to hold back the water of a lake created by a landslide. It also diverts water to a hydropower station with a capacity of 27 megawatts, which is located 300 meters below in the valley of the Cowlitz River near Packwood . During the planning and construction of the dam, care was taken that the structure did not damage the wildlife in the area. The dam raised the water level only a few meters.

Sediment retention structure on the North Fork of the Toutle River. This dam is located about 35 km above where the river meets the Cowlitz River.

A serious side effect of the Mount St. Helens eruption is the transportation of huge amounts of sedimentation material through the North Fork Toutle River. After the eruption , the levels of sediment in the river had increased 5,000 times, making the Toutle River one of the most sediment-saturated rivers in the world. The Toutle River Sediment Retention Structure was built to hold back the sediments before they are washed further downstream and clog the river bed. This would increase floods along the lower reaches and the fairway of the Columbia River would become increasingly shallow. This has to be dredged regularly anyway.

Hydrology

The United States Geological Survey maintains a gauge in Castle Rock . The average annual runoff from 1928 to 2005 was 259 m³ / s. The highest recorded value was 3944 m³ / s on December 23, 1933, the lowest flow rate of 28 m³ / s was measured on November 7 and 8, 1935.

Individual evidence

  1. ↑ USGS - GNIS - Cowlitz River
  2. ↑ Cowlitz River Project ( Memento of the original dated November 16, 2005 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , Tacoma Power (English) @1@ 2Template: Webachiv / IABot / www.ci.tacoma.wa.us
  3. ^ Water Resources Data, Washington, 2005 (PDF; 3.3 MB), USGS

Web links