An Alberta provincial court judge has rejected Syncrude's request to dismiss the two charges it faces in the deaths of 1,600 ducks on a tailings pond north of Fort McMurray two years ago.

The oilsands giant has been on trial on federal and provincial environmental charges in St. Albert since March 1.

Syncrude lawyer Robert White argued Wednesday that the environmental charges have not been substantiated by the Crown and asked for them to be dismissed.

Judge Ken Tjosvold rejected White's motion in a ruling Thursday morning.

White argued the provincial charge should not stand because the hazardous substance on the tailings pond did not leak and contaminate wildlife outside the pond's borders.

Tjosvold did not accept that interpretation, ruling that Syncrude is still obliged to ensure ducks don't land on the pond.

"The provincial law does not require that Syncrude perform the impossible," he said.

"If Syncrude takes all reasonable steps to prevent contamination of birds on its tailings ponds, it can not be convicted under [the provincial statute], even if the birds are contaminated in the ponds."

Syncrude also faces one federal charge under the Migratory Birds Convention Act. White contends that charge does not apply to this case because ducks don't live in or near the tailings pond.

Tjosvold rejected that argument, stating that Syncrude is still responsible for birds that fly over the area.

After Tjosvold finished reading his ruling, White announced he would call no witnesses and rested his case.

Prosecution makes closing arguments

Closing arguments in the nine-week trial began Thursday. Provincial Crown prosecutor Susan McRory completed hers shortly after 11 a.m. MT. Federal Crown prosecutor Kent Brown then needed about half an hour to make his closing argument.

White is scheduled to make his closing arguments on May 5.

Syncrude faces one count under Section 155 of the Alberta Environmental Protection and Enhancement Act for allegedly failing to ensure that hazardous substances directly or indirectly not come into contact or contaminate any animals, plants, food or drink.

It is also charged with one count of violating the federal Migratory Birds Convention Act for allegedly depositing or permitting the deposit of a substance harmful to migratory birds in waters or an area frequented by birds.