Английская Википедия:Flood history in Chehalis, Washington

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Файл:I5LewisFlooding.jpg

Floodwaters over Interstate 5, Great Costal Gale of 2007

The city of Chehalis is located in Washington state and rests upon the Chehalis River. With a connection of creeks, minor tributaries, and basins within or near the city, coupled with the nearby confluences of the Newaukum River south of Chehalis and the Skookumchuck River in neighboring Centralia, the community has suffered from numerous floods. Due to the city being located in the Chehalis Valley along with the Cowlitz River, cresting and overflow of the river has led to flooding in the Chehalis area.

Water inundation from heavy rains and excessive snowmelt has led to a considerable number of historic flooding events in the area, with accounts traced as far back as early Native American settlement and since the beginnings of the city of Chehalis.

Native American flood history

Historical accounts and spiritual lessons passed down through the history of Native American people living in and around the Chehalis River tell of major floods in the basin. Chronicles of the Cowlitz Indian Tribe speak of floods that reached the pinnacle of Mt. St. Helens leading to the beginnings of the tribe. The Chehalis people have traditional stories of floods that led to the transformation of humans and animals and how they interacted between one another and their habitat.

Flood events in the 19th century

Chehalis was founded in 1873 and officially incorporated in 1883. The first newspaper in the town would begin operations that same year.

In the 19th century, two significant floods were recorded in the local newspapers. A flood in December 1887 was stated to have been due in part to heavy rains after a dry summer. Two Chehalis residents died and some local areas were underwater by as much as six feet. River traffic, sawmill operations, and railroads were delayed. Two back-to-back minor floods occurred in December 1897, severely damaging a railroad bridge in nearby Claquato.

Flood events in the 20th century

The 20th century recorded over two dozen notable flooding events in and around the Chehalis community. An episode of rising waters in 1906 on the Cowlitz River would affect the area. A record-setting event in November 1909, was due to the excess rise to the Chehalis and Newaukum rivers which led to the inundation of the Southwest Washington Fairgrounds and caused significant economic losses to lumber milling in the city. A year later in November 1910, a flood, significant enough to come close to breaking records set the year before, was similar to the 1909 event, again due to heavy rains and the overflow of both rivers. Likewise, the waters also inundated the Southwest Washington Fairgrounds where the local rail tracks were covered and a small mudslide occurred. The event shut down gas service to the city for a small time.

In December 1915, the city was hit by a flood from a storm reported as the "Worst in City’s History". The Chehalis and Skookumchuck rivers overflowed and additional rain a few days later caused the banks of the Cowlitz River to be overwhelmed. Damages were reported as limited, but several roads and bridges were washed out and sawmills shut down their operations. Four years later, in January 1919, a deluge was declared as, "Present Flood Probably Worst in City’s History". The three major rivers in the area overflowed and landslides would disconnect travel and communities in the area. The flood was reported to have broken the record for highest depth. A smaller inundation would be recorded in December 1921 that would come within two feet of the record.

Chehalis was submerged in a month-long rain event, totaling over 22 inches, in December 1933. The heavy rains affected most of Western Washington including roads between Portland and Tacoma. Passage between the Twin Cities was closed, and railroad traffic and postal services were disrupted in Chehalis. The city's Alexander Park would be submerged. Flood records were broken and damages were estimated to be as high as $50,000 in the county. Heavy rainfall events in 1936 and 1937 led to additional, moderate flooding, and a 1939 flood submerged the Chehalis–Centralia Airport. A Cowlitz River overflow in 1946 would affect the city.

The Chehalis and Newaukum crested in 1948 after heavy rainfall and would lead to the closure of the airport. The 1948 weather pattern that led to the flood was a widespread disaster for the state. A 1949 rainfall event affected the city as the Cowlitz overflowed. Heavy rains in 1951 and 1953 led to moderate, local flooding. A December 1955 inundation occurred due to a quick rise in the water of the Chehalis River. A wind event, described as a "twister", would hit the area days after. A minor flood would be reported in 1959.

As part of the Christmas flood of 1964, a severe storm in January 1965 led to widespread floods. The event, described by the United States Geological Survey (USGS) as one of the 20th century's worst flood disasters, was ushered in by a weather pattern that dropped 6 inches of rain during the course of a week in the city. Local roads were submerged after the major tributaries crested. The cresting of the Chehalis and Skookumchuck in December 1970 and January 1971 produced moderate floods, with the 1971 incident asserted the worst since 1937.

A major flood occurred in January 1972, becoming the first flood to submerge the new highway, Interstate 5. Almost 5 inches of rain fell over several days leading the Chehalis River to set a flood stage record. While no deaths were reported, schools were closed, dozens of people were evacuated from the city, and the local Yardbirds Shopping Center was under two feet of water. The fairgrounds suffered damages estimated at $250,000 after a levee built in 1952 failed. A cresting of the Chehalis River, twice in January 1974, caused $10 million in losses after a period of heavy rain. Another heavy rain event led to the quick overflow of rivers in the area in 1975. The fairgrounds were spared from major losses due to new pumps that were installed after the 1972 flood, but heavy damages occurred at the Stan Hedwall and Alexander parks after they were submerged. Roads in Chehalis were closed and evacuations required for areas of the city. A smaller flood in 1977 would lead to a closure of a main artery between Chehalis and Centralia.

A major flood disaster developed in November 1986. Caused by 8 inches of rainfall over several days, the city saw damages to two schools and a total of 10 feet of water at the fairgrounds after a levee was breeched. The flood led to a contamination cleanup at a closed industrial site near Millett Field and the surrounding neighborhood. The remediation would not be completed until 1996. The highway would be covered with floodwaters again during a major flood disaster in January 1990. Severe damage was recorded at the fairgrounds and the airport after heavy rains led to the overflow of at-capacity reservoirs in the city. A following flood due to a Western Washington weather event in November of that year led to lowland flooding in the community. A similar flood occurred in April 1991.

100-year flood of 1996

A 100-year flood, part of a widespread flooding event in the Pacific Northwest, with the Chehalis River carrying 49,000 cubic feet of water per second, transpired in February 1996. Setting crest and flood stage records, the Chehalis and Skookumchuck rivers overflowed after 4 inches of rain in one day. The level of water inundation would surpass that as listed on 100-year floodplain maps. A state of emergency was immediately declared and I-5 was closed for 4 days after it was covered in 6 feet of floodwater. Other roads in the area were closed as well, and there were multiple school and business closures. The flood event led to city ordinances directing that existing homes in the Chehalis floodplain be raised 12 inches. Several hundred homes would report significant damages.

Flood events in the 21st century

In the 21st century, several floods of various levels of classification have inundated Chehalis. Minor flooding was reported in 2001 and 2003, leading to road closures.

A record flood in early December 2007 closed I-5 in the city for several days as the highway was covered in Шаблон:Convert of water. Breaking the crest record set in 1996, the Chehalis River would set a flood stage mark of 74.78 feet. Numerous areas in the city were impassable and the local shopping district, which included national restaurant chains and businesses, was submerged. The event was due in part to the Great Coastal Gale of 2007, with questions regarding the severity of the disaster connected to global warming and a combination of poor floodplain development and logging practices. The total cost of damages was estimated by a state commission to be $930 million.

Another major flood, based on heavy rain and a warm weather event that led to sudden snowmelt, materialized over a year later in January 2009. Several regions within Chehalis were immersed and the interstate and railroads were shut down once again. Less severe floods transpired during record daily rainfalls in December 2010 and November 2012. Heavy rain led to a moderate flood event in December 2015 that submerged several homes and businesses in the area.

A stretch of I-5 between Chehalis and Centralia was closed for several hours after a major flood event in January 2022. The closure was a measure of precaution - though the highway was never flooded, several exits and on-ramps were partially submerged. The flood was based on excessive snowmelt and heavy rainfall, leading to a retroactive emergency proclamation from the state governor. The Newaukum River broke its crest record set in 1996 and floodwaters reached as far into the city as the Lewis County Courthouse. Five miles of railroad track used by the Chehalis-Centralia Railroad and Museum were washed out. The severity of the flood led to the Red Cross opening a shelter at the Southwest Washington Fairgrounds and the deployment of the Washington National Guard to help with sandbag operations. Several weeks after the 2022 flood, over 100 structures of various homes and businesses within the Chehalis River Basin had reported damage, with an estimated financial loss of over $2 million.

Chehalis underwent minor water inundation from excessive precipitation during the 2023 Pacific Northwest floods event. Homes and businesses located near W.F. West High School experienced approximately Шаблон:Convert of flood depth, and the accumulation was due in part to an unnamed creek in the area unable to handle the additional flow of water. The extreme rainfall was caused by an atmospheric river and led to flood warnings of the Newaukum River.

History of flood mitigation

During World War II, the United States Department of War and the United States Army Corps of Engineers built levees around the Chehalis–Centralia Airport and in 1942 installed a levee pump. During severe flooding from the Great Coastal Gale of 2007, the pump failed, forcing an intentional break of the levee which led to increased damages to the surrounding community. An electric two-pump station was completed in 2018 with funding provided by the Chehalis River Basin Authority at a cost of $1.14 million. The pumps, able to siphon as much as 12,000 gallons per minute, worked flawlessly during the January 2022 flood event.

Chehalis Basin Flood Authority and Strategy

The Chehalis River Basin Flood Authority, which is overseen and funded by the Washington Department of Ecology Office of Chehalis Basin (OCB), directs flood control measures, flooding concerns, and advance flood warnings for the Chehalis River watershed. Beginning in 2010, Chehalis residents can be alerted via email by the authority's online flood warning system known as the Chehalis Basin Flood Warning System (FWS). The FWS provides information on rainfall, temperature, and river and stream gauge readings in the area.

A Chehalis Basin Strategy partnership was formed in 2014 to mitigate flooding and to restore aquatic habitat, particularly for local Chinook salmon. The alliance is a conglomerate of regional governments in and around Lewis County, in association with Native American tribes, environmental groups, scientists, and local citizens The group offered proposals that outlined several flood control reduction measures, with downstream levee improvements particularly at the Centralia-Chehalis Airport, and a flood retention dam in Pe Ell which is planned to limit catastrophic damage from 100-year floods within the Chehalis River Basin.

The projects are to be carried out in three phases. The first phase began in 2012 and declared achieved in the early 2020s with a combined 140 flood and habitat projects completed at a cost of $152 million. The second stage was implemented soon thereafter and is focused on long-term solutions and strategy for flood control and financial backing of future tasks. The final phase is planned to begin in the mid-2020s and will target construction, additional financing, and devising long-term structural government oversight.

External links

• Chehalis Basin Flood Warning System (FWS)