ABERDEEN, S.D. (AP) — It's been a year since the Keystone pipeline leaked about 407,000 gallons of oil in northeastern South Dakota, and while the issue has been mitigated, a final federal investigation report has yet to be released.

The rural Marshall County site has been cleaned up, but there's still no final investigation report from the federal Pipeline and Hazardous Materials Safety Administration, The Aberdeen News reported .

The Nov. 28, 2017 Keystone leak is the seventh-largest onshore oil or petroleum product spill since 2010. The pipeline is owned by TransCanada and carries crude oil...