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Lake Guides · Severn & Gravenhurst

Trent-Severn Waterway: Lock 42 to Lock 43

This stretch of the Trent-Severn Waterway runs about 23 kilometres down the Severn River and through Sparrow Lake, from Lock 42 Couchiching at Severn Bridge to Lock 43 Swift Rapids (Parks Canada, n.d.-c, n.d.-d). Both locks sit in Ward 5 of the Township of Severn (Township of Severn, n.d.-d), and the Town of Gravenhurst holds shoreline on Sparrow Lake and the Severn River (Town of Gravenhurst, 2024, 2026).

This guide covers what is for sale along this stretch right now and what to check before you buy waterfront here: who owns the riverbed, which permits a dock needs, and how water levels and access work. Kimberly lives in Orillia and owns waterfront herself.

See Severn River Listings Book a Call with Kimberly

Homes for sale on the Severn River

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Listings in Severn and Gravenhurst where the MLS® System records the Severn River as the water body, updated as listings change. The MLS® System treats the river as one water body, so this list can include homes outside this stretch; Kimberly can confirm where a listing sits. Sparrow Lake homes are on the Sparrow Lake guide. A listing entered without a water body will not appear here, so search all waterfront in Severn and Gravenhurst as well. Registered clients also see sold prices and more listing details.

The waterway and its shorelines

Lock 42 Couchiching, at Severn Bridge, carries boats from Lake Couchiching into the Severn River (Parks Canada, n.d.-c). Below it the river widens into Sparrow Lake, then narrows again toward Lock 43 Swift Rapids, where Parks Canada notes the lock is isolated and not practical to reach by road (Parks Canada, n.d.-e, n.d.-d).

Shoreline along this stretch is in the Township of Severn in Simcoe County, and the Town of Gravenhurst in the District of Muskoka holds shoreline on Sparrow Lake and the river (County of Simcoe, n.d.; Township of Severn, n.d.-d; Town of Gravenhurst, 2024, 2026). Parks Canada lists the Severn River and Sparrow Lake among the waterbodies under its jurisdiction (Parks Canada, 2007).

Which municipality a property sits in also matters day to day: it sets the zoning, the building and septic permits, and the property tax rate.

Lock 42 to Lock 43 at a glance

  • Lock 42 Couchiching: average lift 6.2 m, officially opened in July 1920 (Parks Canada, n.d.-c).
  • Lock 43 Swift Rapids: average lift 14.3 m, the highest on the waterway; the present lock was built in 1965 (Parks Canada, n.d.-d).
  • About 23 km between the two locks, by Parks Canada’s kilometre markers (Parks Canada, n.d.-c, n.d.-d).
  • A generating station sits on the Severn River at Lock 43 (Township of Severn, n.d.-d).
  • A CN swing bridge above Lock 42 gives trains priority over boats (Parks Canada, n.d.-a).
  • 2026 lock season: May 15 to October 12 (Parks Canada, n.d.-a).

What to check before you buy between Lock 42 and Lock 43

Waterfront on a federal waterway comes with questions an inland home never raises. These are the ones Kimberly works through with every buyer on this stretch, early, before conditions run out.

Where the lot ends

Parks Canada owns and has jurisdiction over the bed of the Trent-Severn Waterway up to the original upper controlled water elevation, and a title search is needed to confirm how far a property’s ownership extends (Parks Canada, n.d.-b). Your lawyer, and a surveyor where needed, should confirm it before you firm up.

Shore road allowances

Gravenhurst has sold sections of the original shore road allowance on Sparrow Lake and the Severn River to abutting owners (Town of Gravenhurst, 2024, 2026). Ask whether the allowance in front of the lot has been closed and bought, or is still public.

Docks, boathouses and shoreline work

All work on, under and over the bed and waters of the waterway needs a Parks Canada permit, including docks, boathouses, boat lifts, shoreline stabilization and dredging, and no in-water structure is grandfathered (Parks Canada, n.d.-b). Severn also requires a building permit for docks and boathouses, with the Parks Canada permit first (Township of Severn, n.d.-a), and Gravenhurst requires a building permit for a dock connected to the shoreline (Town of Gravenhurst, n.d.).

Water level and flow

Parks Canada manages water levels and flows on the waterway and coordinates outflows from Lake Simcoe and Lake Couchiching to reduce the threat of high water on the Severn River and Sparrow Lake (Parks Canada, n.d.-f). In 2026, high water and flows delayed the opening of Locks 42 to 45 until May 29 (Township of Severn, 2026). Ask how the property handles spring water.

Road or water access

Some properties along the river are reached by private or seasonal roads, and some only by water. Ask who maintains the road, whether it is open all year, and where you would park and launch if the property is water access.

Septic and water systems

In Severn, the discretionary septic re-inspection program that covered Sparrow Lake and the Severn River was suspended at the June 17, 2026 Council meeting (Township of Severn, n.d.-c). Gravenhurst runs a summer septic re-inspection program (Town of Gravenhurst, n.d.). Ask for permit records, and make inspection and water testing part of your conditions.

Kimberly is a REALTOR®, not a lawyer, surveyor or permitting authority. This checklist is a starting point for your own due diligence with those professionals and agencies.

On and around the water

Boating the waterway

Upstream, Lock 42 leads to Lake Couchiching and Lake Simcoe (Parks Canada, n.d.-c). Downstream, Lock 43 Swift Rapids leads toward Big Chute and Georgian Bay (Parks Canada, n.d.-d). Parks Canada notes that lock times are not guaranteed, so allow extra time (Parks Canada, n.d.-a).

Paddling

Parks Canada’s paddling route covers 14.5 km from Sparrow Lake to Lock 43, notes strong winds where the Severn River widens, and tells paddlers to stay well away from the dam beside Lock 43 (Parks Canada, n.d.-e).

Sparrow Lake

The widest part of this stretch has a public beach at its north end and a municipal dock on Port Stanton Parkway (Township of Severn, n.d.-b). See the Sparrow Lake guide.

Services nearby

Orillia Soldiers’ Memorial Hospital is at 170 Colborne Street West in Orillia (Orillia Soldiers’ Memorial Hospital, n.d.), and South Muskoka Memorial Hospital is at 75 Ann Street in Bracebridge (Muskoka Algonquin Healthcare, n.d.).

Thinking about this stretch of the Severn?

Kimberly helps buyers compare frontage, exposure, water depth, access and shoreline permits, and helps owners price Severn River waterfront using recent sales. She owns waterfront herself, so she knows the questions from both sides.

Book a Call with Kimberly What’s My Waterfront Worth? Text Kimberly

Based in Orillia · Serving Simcoe County, Georgian Bay & Muskoka · Sparrow Lake guide

Questions people ask about Lock 42 to Lock 43

Where is the stretch between Lock 42 and Lock 43?

It is about 23 kilometres of the Trent-Severn Waterway, from Lock 42 Couchiching at Severn Bridge, down the Severn River and through Sparrow Lake, to Lock 43 Swift Rapids. Its shoreline is in the Township of Severn and the Town of Gravenhurst.

How big are the locks?

Lock 42 Couchiching lifts boats an average of 6.2 metres. Lock 43 Swift Rapids lifts boats an average of 14.3 metres, the highest lift on the waterway. Lock 43 is isolated and not practical to reach by road.

Who owns the riverbed in front of a property?

Parks Canada lists the Severn River and Sparrow Lake among the waterbodies under its jurisdiction and owns the bed of the Trent-Severn Waterway up to the original upper controlled water elevation. Where private ownership ends on a particular property is confirmed by a title search.

Do I need a permit to build a dock?

Yes, usually more than one. Parks Canada requires a permit for docks, boathouses, boat lifts, shoreline stabilization and dredging on the waterway, and no in-water structure is grandfathered. Severn requires a building permit for docks and boathouses, with the Parks Canada permit first, and Gravenhurst requires a building permit for a dock connected to the shoreline.

When are the locks open?

In 2026 the Trent-Severn locks run from May 15 to October 12. Parks Canada notes that opening and closing times are not guaranteed, and a CN swing bridge above Lock 42 gives trains priority over boats.

Related: Map of all lake guides · Sparrow Lake guide · Lock 43 to Lock 44 guide · Lake Couchiching guide · Oro-Medonte and Severn guide

Sources & References

Geographic, regulatory and amenity facts on this page come from the public sources below (APA style). Live listings come from the MLS® System through PropTx Innovations Inc. and are shown on the listings themselves.

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