 The Sierra Club has lodged a formal complaint with the SFI, alleging that Weyerhaeuser engaged in risky and irresponsible logging on steep slopes that led to 1,259 landslides in 2007 on SFI-certified Weyerhaeuser lands in Washington state.Challenging SFI to back up its claims of 'independence' and 'rigorous audits,' the Sierra Club requested that Weyerhaeuser's SFI certification be revoked.A peer reviewed landslide study concluded that the Washington State landslides that the Sierra Club attributed to Weyerhaeuser's logging practices were the result of extreme weather conditions such as heavy rainfall and not the result of steep slope logging by the company.