Forterra (formerly Cascade Land Conservancy), based in Seattle, Washington, US, is the state of Washington’s largest land conservation, stewardship and community building organization dedicated solely to the region. The Cascade Land Conservancy is a non-profit, 501(c)(3) organization governed by a Board of Directors.

Currently, Forterra operates in multiple counties. Principal offices are in Seattle, Ellensburg, and Tacoma.

Forterra has conserved 180,000 acres (730 km) of working farms, forestlands and natural areas to date. Some of the major conservation projects include 118-acre (0.48 km) Saddle Swamp, 300-acre (1.2 km) Maury Island Marine Park and 90,000-acre (360 km) Snoqualmie Tree Farm.

Forterra has official partnerships with the cities of Everett, Kent, Kirkland, Redmond, Seattle, and Tacoma in leading stewardship projects at city parks and urban forests. Public volunteers and volunteer Forest Stewards work with cities and Cascade Land Conservancy in implementing 20 year plans to protect urban forests from invasive plants.

On November 2, 2011, Cascade Land Conservancy officially changed the organization's name to 'Forterra' (meaning 'for the earth') in order to reflect the organization's changing goals. As Washington State's largest conservation and stewardship organization, the 'Cascade' in the name did not reflect the statewide work area. 'Land Conservancy' likewise no longer embodied the purpose of the organization.

The Green Seattle Partnership is a partnership between the City of Seattle and Forterra with the goal of combating invasive species and preserving parklands in Seattle, Washington.

Coordinates: 47°36′21″N 122°19′54″W / 47.605935°N 122.331783°W / 47.605935; -122.331783