The Alberta Energy Regulator has laid five charges against Nexen stemming from a July 2015 pipeline spill at its Long Lake oilsands facility south of Fort McMurray.

The charges were laid under the Environmental Protection and Enhancement Act and the Public Lands Act after a spill of five million litres of emulsion, a mixture of crude bitumen and processed water, that affected an area of 21,900 square metres.

The charges include:

One count under the Environmental Protection and Enhancement Act (EPEA) for releasing a substance to the environment that caused or may have caused an adverse effect.

One count under the EPEA for failing to report the release of the substance as soon as possible.

One count under the EPEA for failing to take all reasonable measures to remediate.

One count the EPEA for failing to take all reasonable measures to remediate, manage, remove or dispose of the substance to prevent an adverse effect.

One count under the Public Lands Act for causing a disturbance to public land.

A first appearance is scheduled for Aug. 16 in Fort McMurray provincial court.

"Producing oil or gas in Alberta comes with a responsibility to follow all requirements to protect the public and environment," AER president and CEO Jim Ellis said in a news release Thursday.

"When we believe that the rules are not followed, we have a variety of tools, including laying charges that we can and do use in an attempt to ensure that potential offenders are held accountable."

In July 2016, one year after the spill, Nexen reported that its own investigation had found the pipeline buckled and ruptured because its design was incompatible with the muskeg ground conditions.

The Long Lake upgrader has not operated since an explosion in January 2016 killed two workers.