Acadia’s Gateway Paddle
The Union River flows through Ellsworth and empties into Union River Bay, a sheltered arm of Frenchman Bay just minutes from the turnoff to Mount Desert Island and Acadia National Park. This tidal estuary paddle is a hidden gem that most Acadia visitors drive past without knowing it exists. The river offers calm water, wildlife viewing that rivals anything on Mount Desert Island, and a convenient location for paddlers who want to add a water day to an Acadia trip.
The tidal section below Ellsworth Dam runs roughly four miles to the bay, winding through salt marshes and mudflats that support a rich ecosystem. Harbor seals haul out on ledges at low tide. Great blue herons stalk the shallows. Osprey nest on platforms along the banks. And in late spring and summer, Atlantic salmon migrate upstream through this corridor on their way to spawning grounds, part of an ongoing restoration effort on the river.
This is an easy paddle suitable for families and beginners, with the main consideration being tidal timing. The estuary drains significantly at low tide, exposing mudflats that can strand boats in shallow channels.
The Union River estuary drains dramatically at low tide. What looks like a navigable channel at high water can become a mud flat within a few hours. Always check the Ellsworth tide tables and plan to be on the water within two hours of high tide. Getting stranded on the mud is not dangerous but it is inconvenient and messy.
Paddling the Estuary
The put-in below Ellsworth Dam offers easy access to the tidal section. From here, paddle downstream through the widening estuary. Basic kayaking gear is all the sheltered channel requires. The river channel is well-defined at higher tides, flanked by salt marsh grasses and occasional rocky points. The banks are a mix of conservation land and residential properties, with most of the shoreline maintaining a natural buffer.
As you move downstream, the estuary opens into a broader basin where the Union River meets its tidal bay. This area is excellent for wildlife watching, and a pair of binoculars earns its place in the boat. Seal ledges appear on the eastern side, and on summer mornings you can often see a dozen or more harbor seals basking. Eagles patrol the shoreline, and at the right tide you can explore side channels through the marsh grass.
The paddle to the bay and back covers roughly eight miles round trip, taking three to four hours at a comfortable pace. You can shorten the trip by simply turning around whenever you like, as the river is navigable for its full tidal length at higher water.
The estuary is at its best in the early morning, especially on a rising tide. Seals are more active, herons are feeding in the shallows, and osprey are making their first fishing runs of the day. You will also avoid the afternoon wind that sometimes funnels up the bay. A dawn paddle with coffee in a thermos is one of the finest experiences near Acadia.
Salmon and Fish Viewing
The Union River is one of Maine’s designated Atlantic salmon rivers, and the fish passage at Ellsworth Dam allows salmon to migrate upstream from May through October. While the salmon population remains small and fishing for Atlantic salmon is catch-and-release only, seeing these fish in the river is a meaningful experience. The restoration effort involves the removal of upstream dams and habitat improvement projects that have been ongoing for decades.
Below the dam, alewives run upstream in enormous numbers in May and June. The fish ladder can be viewed from a platform near the dam, and watching thousands of alewives navigate the passage is a spectacle that draws both people and predators. Eagles, osprey, and seals all concentrate near the dam during the alewife run.
Visit the fish ladder viewing platform at Ellsworth Dam during the last two weeks of May for the peak alewife run. The concentration of birds is remarkable. After watching the fish ladder, launch your kayak from the access point just below the dam and paddle downstream. You will likely see eagles fishing from the trees along the first mile of river.
When to Go
Spring
Alewife runs in May draw eagles and osprey. Water is cold. Spectacular wildlife viewing.
Summer
Warm weather, harbor seals on ledges, calm conditions. Best for casual paddling.
Fall
Foliage along the banks, migrating shorebirds, fewer paddlers. Cool mornings.
Winter
Cold water, wind exposure on the bay, limited wildlife. Not recommended.
Summer is the most comfortable season, with warm air temperatures, calm mornings, and seals reliably present on the ledges. Spring offers the most dramatic wildlife viewing during the alewife run. Fall is peaceful, with foliage reflected in the still water of the estuary on calm mornings.
Practical Information
The Ellsworth area has kayak rentals available through local outfitters, and some offer guided estuary tours that include natural history interpretation. If you are bringing your own boat, the launch below Ellsworth Dam is straightforward with free parking for eight to ten vehicles.
Cell service is good throughout the paddle. Ellsworth is a full-service town with restaurants, grocery stores, gas stations, and hotels. It is the last major supply stop before crossing to Mount Desert Island and Acadia.
Packing List
Union River Estuary Paddle
- Kayak or canoe
- PFD/life jacket for every paddler
- Binoculars for seal and bird viewing
- Tide chart (check before launching)
- Sunscreen and hat
- Water and snacks
- Dry bag for phone and keys
- Camera with zoom lens
- Water shoes (mudflats if you misjudge the tide)
Getting There
The primary launch is below Ellsworth Dam, accessible from Route 1 in downtown Ellsworth. From Bangor, take Route 1A east to Ellsworth, about 30 minutes. From Bar Harbor, Ellsworth is 20 minutes north on Route 3. The put-in is off Water Street near the dam.
GPS coordinates for Ellsworth Dam launch: 44.5430, -68.4219
FAQ
Is the Union River good for beginners?
Yes. The tidal estuary is calm flatwater with no rapids or significant current. The only skill required is basic boat handling and an understanding of tidal timing.
Can I see seals on the Union River?
Harbor seals are regularly seen on ledges in the lower estuary, especially in summer. They haul out on exposed rocks at lower tides. Keep a respectful distance of at least 100 yards.
Do I need a fishing license?
Yes, a Maine fishing license is required. Atlantic salmon are strictly catch-and-release. Other species including striped bass, alewife (when open), and brown trout are available seasonally.
How does this paddle compare to kayaking in Acadia?
The Union River estuary is calmer and more sheltered than open-water paddling around Mount Desert Island. It is a great option for paddlers who want wildlife viewing without dealing with ocean swells, fog, and cold water.
Is there parking at the launch?
Yes. Free parking for 8-10 vehicles at the access point below Ellsworth Dam. On busy summer weekends, arrive early to secure a spot.
