Construction progresses on Mosquito Bridge in El Dorado County, now 87% complete.
Construction on the Mosquito Bridge replacement project continues to advance as crews and contractors reach a major milestone this spring, according to the April 2025 construction update from El Dorado County.
Now nearly 87% complete, the project has moved into a critical new phase: building the bridge’s superstructure segments.
Since breaking ground in July 2022, the new 1,200-foot-long span has steadily taken shape over the South Fork of the American River, replacing the aging and narrow timber suspension bridge built in 1939. The $93 million project, primarily funded through the federal Highway Bridge Program and state contributions, was awarded to Shimmick Construction.
Recent work through March and April of this year has focused on installing and pouring the upper stem and diaphragm concrete at both Pier 2 and Pier 3—massive vertical supports rising from the steep canyon walls. These pours follow months of intricate formwork, rebar installation, thermal control preparation, and falsework dismantling.
On April 23, Pier 3’s upper diaphragm concrete was successfully placed, with Pier 2 scheduled for final placement on May 2. With these pier table components nearly complete, crews are now preparing to assemble the bridge’s form travelers—movable scaffolding that allows builders to construct the bridge segment by segment outward from the piers. This method, known as balanced cantilever construction, is essential for spanning such a deep and rugged gorge.
Mosquito Bridge Construction Video
To support the next phase of construction and ensure public safety, El Dorado County has announced a 10-week road closure on Mosquito Road at the project gates from May 27 to August 3, 2025. During this time, crews will perform drainage work, monthly crane inspections, and multiple concrete pours for the bridge’s north superstructure segments. Traffic will be rerouted via Rock Creek Road, as intermittent closures and equipment staging are expected throughout the summer.
Initially expected in late 2025, the bridge is now projected for completion in March 2026, according to the latest county update. Once open, it will provide a modern, two-lane crossing with full load capacity—critical for residents in the Mosquito and Swansboro communities who have long relied on the one-lane wooden bridge with its 5-ton weight limit.
El Dorado County plans to preserve the historic bridge for pedestrian and bicycle access after the new span opens, maintaining a physical link to the region’s Gold Rush–era infrastructure.
