Tehaleh, formerly known as Cascadia, is a master-planned unincorporated community to the south of Bonney Lake in Pierce County, Washington, United States. Construction began in 2005 with an estimated timeline for completion of 20 years. The town was designed by Patrick Kuo, who had purchased the land in 1991. Included in the original plan for Cascadia were 6,500 homes, a commercial district, an industrial park, schools, and recreational parkland for residents to enjoy. Construction halted in 2008, prior to the construction of any homes or commercial properties. After foreclosure proceedings in 2010, Homestreet Bank repossessed much of Kuo's land, intending to find another developer.

Pierce County is a county in the U.S. state of Washington. As of the 2020 census, the population was 921,130, up from 795,225 in 2010, making it the second-most populous county in Washington, behind King County, and the 59th-most populous in the United States. The county seat and largest city is Tacoma. Formed out of Thurston County on December 22, 1852, by the legislature of Oregon Territory, it was named for U.S. President Franklin Pierce. Pierce County is in the Seattle metropolitan area.