Cotnam Island, located in the Ottawa River east of Pembroke, holds a distinct position in Renfrew County's land division story. The island lies near the confluence of the Muskrat River and is part of Laurentian Valley. Historically, it served both as seasonal Indigenous land and as a locus for early settler farming and trapping in the mid-to-late 19th century.

The island's parcels were not laid out in the standard concession-lot format typical of Ontario townships. Instead, much of the land is described in metes and bounds, often using natural features like shoreline curves and vegetation changes. Frequent flooding and ice movement along the river have altered both topography and boundary clarity over time. Farming families occupied the island through much of the early 20th century, but it gradually transitioned to seasonal cottages and is now largely recreational.

From a cadastral perspective, Cotnam Island is a study in adaptive boundary work. Legal descriptions often require interpretation of ambiguous or outdated natural references, and aerial photography is frequently consulted alongside historic survey sketches. Title work here must account for shifting water levels, Crown shoreline reservations, and in some cases, informal occupancy lines not registered in official plans. Surveyors must be cautious about changes to lot size, shoreline encroachment, and access issues.