Lock 22 — Lock 22 – Nassau Mills

Lock 22 sits on the Otonabee River at Kilometre 151.7 (Mile 94.3) of the Trent-Severn Waterway, just upstream of Trent University in Peterborough, Ontario. It is the first lock northbound boaters encounter after transiting the Peterborough Lift Lock, and it marks the beginning of a series of five closely spaced, manually operated locks that carry the waterway north to Lakefield. The surrounding parkland connects to the Lakefield Millennium Trail, a popular walking and cycling route that follows the river valley between Peterborough and Lakefield. CHS Sailing Directions warn of strong cross currents on the southern approach, and a narrow concrete-walled channel just below the lock restricts the waterway to 13.7 m45 ft in width with a depth of only 1.8 m6 ft.

The area around Nassau Mills was first surveyed in 1835, though it was not until 1895 that the federal government approved canal construction on the Peterborough-to-Lakefield reach of the waterway. The contract was awarded to the firm of Brown, Love and Aylmer, who constructed dams to flood the river rapids and built locks to bypass the resulting impoundments. Lock 22 is a slow valve gate lock — one of several hand-operated locks in this section that still use the original gate valve mechanism, making the locking process noticeably slower than the hydraulic and standard locks found farther south on the system.

For boaters, Nassau Mills offers a welcome change of pace from the busier Peterborough locks. The upper lock area provides a peaceful overnight tie-up with well-maintained picnic grounds and generous parkland — Parks Canada permits mooring for up to two nights. There is no shore power or fuel at this lockstation, so plan accordingly. The painted blue line on the west wall below the lock is reserved for transit staging during operating hours and is not available for overnight mooring. Downtown Peterborough and its full range of restaurants, groceries, and marine services are approximately 7 kilometres south by road. Trent University’s campus is within walking distance, though boater-accessible food options at the lock itself are limited.

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📍 GPS: 44.3653615°N, 78.2926905°W · 3779 Nassau Mills Road, Peterborough, Ontario, Peterborough, Ontario, ON · Get Directions ↗ · Street View ↗

For navigation, use CHS Chart #2023 — this map is for reference only and should not be used for marine navigation.

Boater Orientation Notes:

• Lock 22 is in a semi-rural setting adjacent to Trent University — very few commercial amenities within walking distance.
• Campus dining (Starbucks, Seasoned Spoon, Tim Hortons) follows academic schedules — reduced hours or closed in summer. Always verify before walking.
• All grocery, LCBO, hardware, and pharmacy require a taxi (~5—10 min) into Peterborough’s north end.
• Paris Marine (3.5 km north on Lakefield Rd) is the closest full-service marine dealer — highly rated by TSW boaters for emergency repairs.
• Lakefield Millennium Trail is accessible directly from Lock 22 heading north toward Lakefield — excellent for walking and cycling.

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Last Updated: March 18, 2026

The dam at Nassau Mills is well upstream of the lock itself, but because of the way the finger comes off the entrance, you’ll see a lot of swelling and eddies right around the mouth of the lock walls. Be ready for that — it’s not dangerous, but the water won’t be flat coming in. Blue line is on the starboard side. No drama in the chamber itself. Cute little place to stop, and plenty of room for the dog to run if you need to stretch. HEADS UP AT THE TOP: I’ve been gusted around quite a bit as you come back up to the higher land level above the lock. You’re suddenly exposed to wind that the lower approach was sheltered from, so don’t get caught flat-footed when you come out of the chamber and the breeze hits you.

Weather data for navigation planning purposes only. Always check Environment and Climate Change Canada’s official marine forecast before making operational decisions. weather.gc.ca ↗