Exploring Cosumnes River Preserve’s Hiking Trails: Birding Paradise Beside I-5

Hiking Cosumnes River Preserve’s River Walk Trail, Wetlands Walk Trail, and Boardwalk Trail let you enjoy the natural beauty of this spectacular area, including myriad birds, a wide array of animal species, plus diverse riparian plant species.

Sandhill cranes at Cosumnes River Preserve. Many waterfowl and other birds spend part of the winter here..
Sandhill cranes at Cosumnes River Preserve. (Photo by Bob Wick, BLM)

Easy to access off I-5 about midway between Sacramento and Stockton, the Cosumnes River Preserve is a great hiking/walking destination year-round, but it’s especially attractive in winter when you can observe many thousands of migrating geese, ducks, and other waterfowl.

This post presents the three main hiking trail options for exploring Cosumnes River Preserve: the River Walk Trail, the Wetlands Walk Trail, and the Boardwalk Trail; it’s easy to do all three in a few hours.

Cosumnes River Preserve: Driving Directions From I-5

On Interstate 5 about 21 miles south of downtown Sacramento and 25 miles north of downtown Stockton, take Exit 498 for Twin Cities Road. Turn left if coming from the Sacramento direction (or right if coming from the Stockton direction). Go east 0.8 mile and then turn right on Franklin Boulevard, just before the railroad tracks. Continue south 1.8 miles (passing the Boardwalk Trail parking lot) and then turn left into the Cosumnes River Preserve. Park in the lot farthest east and closest to the visitor center.

Cosumnes River Preserve: General Information for Hikers

Family-friendly: Yes! Lots of interesting information and sights for kids
Dog-friendly: No, dogs prohibited
Bike-friendly: No, bicycles not allowed
Amenities: bathrooms in the upper parking lot, and at the visitor center (when open); non-motorized watercraft can be launched from the Preserve’s dock, located on Middle Slough
Contact/Map: Cosumnes River Preserve; download map and nature trail guide from the website
Trailhead GPS: N 38° 15.953′ W 121° 26.389′
More key info: trails open approximately sunrise to sunset; the River Walk Trail can be flooded in winter; visitor center usually open 365 days a year with variable hours (generally 8 a.m. to 5 p.m. Mondays through Fridays, and 9 a.m. to 5 p.m. on weekends and holidays) obtain nature trail guide PDF from website or print version from the visitor center ; winter features large numbers of migratory birds; trailside poison oak; waterbird numbers are highest November through February, while  late spring and summer bring large numbers of neotropical migratory songbirds

Cosumnes River Preserve: Visitor Center

If the visitor center is open, make sure to spend at least a few minutes exploring its fascinating exhibits about local natural history, along with details of the many things visitors can see and do at Cosumnes River Preserve.

Cosumnes River Preserve Hiking Trails Map: River Walk Trail, Wetlands Walk Trail, Boardwalk Trail ADA compliant
Cosumnes River Preserve hiking trails map: River Walk Trail, Wetlands Walk Trail, Boardwalk Trail. (Courtesy Cosumnes River Preserve)

Cosumnes River Preserve: River Walk Trail

Distance: 3.8 miles
Elevation Gain: negligible
High Point: 15 feet
Difficulty: Easy

A partnership of seven different public and private agencies, the Cosumnes River Preserve extends over 50,000 acres in the Sacramento-San Joaquin Delta. The part featured here is easily accessed from I-5 and takes you through a wide variety of plant habitats, including along the Cosumnes River, giving you the opportunity to see a wide variety of bird species, especially during the winter migration season.

Note that there are a lot of trail forks. This hike follows the numbering of the first 23 posts of the nature trail, so download that ahead of time; you can also help keep your bearings by noting the location of the railroad tracks and the Cosumnes River. At each major intersection you’ll find a trail guide mounted on a metal post.

Start the Hike at Willow Slough

To find the trail, look for the prominent sign for the Wetlands Walk Trail and River Walk Trail on the left as you face the visitor center with the parking lot at your back. The two trails share a boardwalk and bridge as they go east for the first 0.1 mile. You’ll definitely want to stop in the middle of the bridge over Willow Slough to absorb the lush greenery of willows and cottonwoods, and to look for great egrets, great blue herons, pond turtles, and a variety of other birds and wildlife.

Cosumnes River Preserve, Willow Slough bridge: great egret, willows, cottonwoods.
Cosumnes River Preserve: Great egret viewed from the Willow Slough bridge

Reach a trail fork just beyond the trees on the far side of Willow Slough. The Wetlands Walk Trail (and a way to reach the Boardwalk Trail) goes left, but you go right on the River Walk Trail. The way now heads south on the dirt path. Lush greenery borders Willow Slough on the right; to the left lie managed wetlands that are flooded in winter to provide habitat for migrating waterfowl, but are dry from spring through late fall.

An access road forks left at 0.4 mile between posts 6 and 7; stay straight on the main River Walk Trail route. The easterly vista includes cottonwoods, willows, valley oaks, and railroad tracks. Soon reach a viewpoint of Middle Slough, much larger than Willow Slough and another good place to pause and watch the wildlife. Continuing, note a freshwater seasonal marsh on the left, and then reach a fork at 0.6 mile. If you wish, make the quick jaunt straight (south) to post 11 near the confluence of Middle Slough and the Cosumnes River and then return, but the main route bears left and east.

Walk along a seasonal marsh that is frequently bordered by cattails. This is your best opportunity to see migrating ducks and geese in winter, and great blue herons, great white herons, and redwing blackbirds the rest of the year.

Arrive at another junction at 0.8 mile, near the railroad tracks and post 13. Turn right and go south 0.1 mile to another junction, where you again go right. Walk west by southwest, and then due south to a valley oak grove and post 14 at 1.2 miles.

The River Walk Trail Reaches the Cosumnes River

Curve southeast to reach post 17 at 1.4 miles. Leave the main River Walk Trail and take the short path to the right that takes you to the banks of the Cosumnes River, a beautiful spot to stand or sit in the shade and watch the water flow. The Cosumnes River begins in the high Sierra south of Lake Tahoe in El Dorado County and flows about 53 miles through the Sierra foothills and the San Joaquin Valley to end at the Mokelumne River just a half mile downstream; it’s one of the few Sierra Nevada rivers with no significant dams.

Return to the main River Walk Trail and go right (east) for 0.1 mile, and then curve north and walk near the railroad tracks for another 0.1 mile to a trail fork at 1.6 miles. Go right (east) to pass under the railroad tracks. Continue east through extensive oak savanna and past post 19 to yet another junction at 1.9 miles, which you’ll return to shortly after you do the short loop with posts 20 and 21.

For now, go straight across and continue briefly east and then southeast to post 20 at 2.1 miles, where Tihuechemne Slough meets the Cosumnes River, a favorite spot for white egrets and great blue herons. Go westerly near the banks of the Cosumnes River to post 21 and a rare (for here) live oak tree before walking north to close the loop at 2.4 miles at the most recently encountered trail junction (encountered at 1.9 miles).

At this trail junction go straight (northerly) across the open savanna to meet another broad path at 2.6 miles. Cross this path and walk northwest to post 22 at 2.7 miles, where you’ll see magnificent valley oaks and a tule marsh frequented by redwing blackbirds.

From here, the River Walk Trail goes southwest 0.2 mile to post 23 and the railroad tracks, which you cross. You are now back on previously walked trail. Go north 0.1 mile to the junction near post 13, turn left and walk west to near Middle Slough, and then turn right to walk north back to the bridge that crosses Willow Slough and returns you to the trailhead.

Note: If you’re also doing the Wetlands Walk Trail and Boardwalk Trail, continue straight (north) for 0.5 mile instead of retracing your steps to the Willow Slough bridge (see below).

Map showing Cosumnes River and Mokelumne River flowing into the San Joaquin River.
Map showing Cosumnes River and Mokelumne River flowing into the San Joaquin River. (Courtesy Wikipedia)

Cosumnes River Preserve: Wetlands Walk Trail and Boardwalk Trail

Distance: 1.5 miles
Elevation Gain: negligible
High Point: 15 feet
Difficulty: Easy

The ADA-compliant Wetlands Walk Trail makes it easy for just about everyone to enjoy the beauty of Cosumnes River Preserve. The loop trail takes you along willow-lined sloughs and past seasonal wetlands, the latter covered with thousands of migratory birds in late fall and winter. In addition, you’ll win vistas of the Sierra Nevada and the Coast Range, including Mount Diablo.

The Wetlands Walk Trail begins near the Visitor Center, on the left as you come up from the parking lot; you’ll see the sign for the Wetlands Walk Trail (this hike) and the River Walk Trail (described above). The wooden boardwalk runs east to quickly reach the bridge spanning Willow Slough. This bridge offers the perfect opportunity to pause and observe the still waters and winged wildlife of the willow-bordered slough. Signs explain that the slough’s water level rises and falls in tandem with the ocean tides—the elevation here is only five feet.

When you’re ready, continue east to a trail junction at 0.1 mile. The River Walk Trail goes to the right, but you turn left on the Wetlands Walk Trail and wander north. On the left are valley oaks that border the banks of Willow Slough. On the right a seasonal marsh stretches east to the railroad tracks; you’ll spot distant willows and cottonwoods growing in places with summer moisture, and you’ll also spy the occasional valley oak.

Look on the left for a pole with a nesting box for tree swallows at post 24; if you look closely as you continue the hike, you’ll also see nesting boxes for wood ducks. Just beyond post 24 a picnic table rests underneath oak shade.

At post 25 at 0.2 mile is a small side trail on the left that runs 100 feet into a grove of valley oaks. The main Wetlands Walk Trail swings briefly right (east) and then curves left to resume its northerly course. Quickly reach and then cross a bridge across Willow Slough, noting the many tules that grow in and near the willow-lined slough.

Once past Willow Slough the Wetlands Walk Trail runs west and then north through oak savanna. The valley oaks here are all quite small; they were planted by volunteers in 1988. From here until the end of the hike there is almost no shade. Travel beside a smaller slough lined with lush vegetation and past a trailside bench to another bench beside a year-round pond and post 28 at 0.5 mile. The pond is an excellent spot to watch wildlife: look for turtles, river otters, great blue herons, and more.

The path is quickly bordered by the railroad tracks on the right and Franklin Boulevard on the left, and then it goes left and briefly west to cross Franklin Boulevard. (Watch children closely as traffic does not stop for pedestrians.)

Once on the far side of Franklin Boulevard the Wetlands Walk Trail begins a long southerly run past more benches, with a clear view to the west of the hills and mountains of the Coast Range, anchored by Mount Diablo to the southwest. Franklin Boulevard runs close by on the left, with a seasonal pond on the right. This pond is flooded in fall and winter, when it provides prime habitat for sandhill cranes.

Cosumnes River Preserve: Boardwalk Trail

Arrive at the parking lot for the Boardwalk Trail at 0.7 mile. Leave the Wetlands Walk Trail and take the Boardwalk Trail west, passing seasonal wetlands filled with tules and willows, plus wildflowers in spring and early summer. The Boardwalk Trail ends at a viewing platform. When you head back to the Boardwalk Trail parking lot, you’ll see the distant Sierra Nevada to the east, crested by snow from late fall well into summer.

Return to the Boardwalk Trail parking lot at 1.2 miles. Turn right to resume hiking on the Wetlands Walk Trail. Continue south with a small pond on the left and seasonal wetland on the right, until the path swings east at 1.5 miles to cross Franklin Boulevard and quickly return to the trailhead.

Note: you can hike just the Boardwalk Trail by parking in the lot on your right about 0.3 mile before the main Cosumnes River Preserve parking lot described above.

Cosumnes River Preserve: Video at Willow Slough

Here’s a short Youtube video I shot from the bridge across Willow Slough, which is at the beginning of both the River Walk Trail and the Wetlands Walk Trail:

My Northern California Hiking Trails Youtube channel has dozens of trail videos from all over the North State.

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