Sisters Island Lighthouse is 12.5 miles northeast of Alexandria Bay. The stone structure was built in 1870, and housed a sixth-order Fresnel lens in a 60-foot tower incorporated into the keeper's residence. The lighthouse and neighboring shed are the only structures on tiny Three Sisters Island. Once three separate islands, the islands are now linked together.

The lighthouse was built to mark a difficult channel on the Canadian side of the island. It took nine years of negotiation before the lighthouse was actually built. After the lighthouse entered service, the channel was relocated to the American side of the island. Bedrock at the bottom of the river was blasted to clear the channel. During a storm, a barge carrying dynamite exploded, killing nine crew members.

The first keeper was Civil War veteran William Dodge, who was replaced by his son. Together, the Dodge family served the Sisters Island light for 51 years. Horace Walts later served both Sisters Island and Sunken Rock.

In about 1890 the passenger steamer Ocean collided with the barge Kent. The Dodges were awakened by a violent crash as the Ocean hit the rocks at Sisters Island, her captain steaming his sinking vessel at full speed to the shallow island waters.

One serious annoyance at Sisters Island was the numerous shadflies which inhabited the area. These large insects would occasionally block the oxygen intake of the lamp and extinguish the flame. If this were not enough, the resulting gas leak was a hazard to the entire station. When the shadfly population was high, the keepers had to constantly monitor the flame.

With the opening of the St. Lawrence Seaway in 1959, the light was replaced by a nearby buoy. Today, the light is a private residence and is no longer active.

References (see links)

Seaway Trail Lighthouses (2nd Edition), Tinney, Burdette-Watkins, p. 45
Lighthouses of the Seaway Trail (video)
19th Century Lights, Clifford p. 207