The ship suffered two serious incidents in her career: a 1969 explosion and ensuing fire that killed nine, and a 1989 collision that required the complete replacement of her bow.

[7] The destroyers were also equipped beginning in 1958 with Mk 43 homing torpedoes in an effort to increase the distance between the ships and their targets.

[8] As part of the 1964 naval program, the Royal Canadian Navy planned to improve the attack capabilities of the Restigouche class.

[9] By 1969, the budget for naval programs had been cut and only four out of the seven (Terra Nova, Restigouche, Gatineau and Kootenay) would get upgraded to IRE standards and the remaining three (Chaudière, Columbia, and St. Croix) were placed in reserve.

[16] However, by the time the ships emerged from their refits, they were already obsolete as the Falklands War had changed the way surface battles were fought.

Kootenay was commissioned into the Royal Canadian Navy on 7 March 1959 at North Vancouver with the classification DDE 258.

[19] In August 1960, the destroyer escort, along with sister ships Terra Nova, St. Croix and Gatineau, took part in the 500th anniversary of Prince Henry the Navigator's death off Lisbon.

[20] In March 1961, the destroyer escort was among the ships that took part in a combined naval exercise with the United States Navy off Nova Scotia.

[22] On 23 October 1969 Kootenay was operating in European waters with a Canadian task group comprising the aircraft carrier Bonaventure and seven other destroyer escorts.

The task group was returning to Canada, transiting the English Channel when Kootenay and Saguenay separated from the rest of the ships to perform sea trials of their engines, roughly 200 miles (320 km) off Plymouth, United Kingdom.

[25] While the fire burned, the ship turned in large circles at full speed for 40 minutes, and the intense heat created a bulge in the starboard side of the vessel.

Flares were fired to alert other ships, and Saguenay and Bonaventure responded to Kootenay's distress, airlifting supplies and personnel to the destroyer.

Her propellers were removed there and she was then towed to Halifax, Nova Scotia by the salvage tug Elbe, leaving Plymouth on 16 November.

[27] In July 1978, Kootenay assisted the Royal Canadian Mounted Police in intercepting $28 million worth of marijuana off the coast of British Columbia.

[28] In October 1981, Kootenay, along with the replenishment ship Provider, tracked a Soviet force operating in the Gulf of Alaska.

[30] On 1 June 1989, Kootenay collided with the merchant vessel MV Nord Pol in fog approximately 28 miles off Cape Flattery.

[28] In order to fix the damage, her bow was removed and replaced with that of sister ship Chaudière which was out of service at the time.

In 1994, the destroyer escort was deployed off the coast of Haiti to enforce the blockade sanctioned by the United Nations.