By Allison Lampert

MONTREAL (Reuters) - An industrial contamination lawsuit brought a quarter century ago has been dismissed by the Supreme Court of Canada, bringing an end to a case dating as far back as 1924 that involved black tar so sticky that horses caught in its grip had to be shot.

The Supreme Court of Canada this week refused to hear a case filed by Canadian National Railway Co. in 1989, relating to the contamination.

It pointed to lower court decisions that questioned how a fair trial could be held about a tar spill that CN said traced back to between 1924 and 1958.

"By the time the litigation commenced in June 1989, the issues were already 30 to 65 years old," court documents said.

"While the first 14 years of delay were excusable, the delay between the years 2003 and 2014 was inordinate and inexcusable," the Ontario Superior Court of Justice said in 2014.

Court documents said that CN never responded to requests in 1997 by the Ontario town of Kitchener to examine five elderly witnesses, some of whom were ill.

Montreal-based CN said that tar produced as a by-product of a coal gasification plant operated by the town migrated on to its property between 1924 and 1958, according to court records.

CN alleged that the city was dumping the coal tar on neighboring lands owned by the defendant, Hogg Fuel & Supply Ltd.

The tar, a black to brown liquid, was once described in trial records as a "gooey substance" so sticky some horses were caught in it and had to be shot.

CN was seeking between C$1 million to C$2 million from Hogg Fuel and Kitchener to clean up its land, plus other costs, court documents said.

The case was filed in 1989, just after Ontario's environment ministry told CN it was preparing to order the "owners of polluted sites and the former gas plant operators to clean-up the contaminated lands," superior court documents show.

CN declined to comment on Friday.

(Reporting By Allison Lampert)