The new St. Croix River bridge won't open until late 2017, a full year after originally planned, because of equipment problems, material shortages and weather delays, Minnesota and Wisconsin transportation agencies said Wednesday.

The announcement was the first official acknowledgment of a new project schedule since the agencies reported in September that a string of problems had slowed construction and that the original 2016 completion date no longer was attainable. Officials attributed the delay to the same factors they had previously blamed for falling behind schedule.

Just how the delay might affect the overall cost of the bridge project — budgeted for as much as $676 million — won't be known until the state agencies complete negotiations with the general contractor, said Kevin Gutknecht, Minnesota Department of Transportation (MnDOT) spokesman.

"We believe this new date is well within the project team's capability to meet," said Michael Beer, MnDOT's project director. "It is a large and complex project, and we want to be sure that it is done safely and meets our high standards for quality."

The road portions of the project remain on track, Beer said. Improvements to Hwy. 36 in Minnesota and Hwy. 64 in Wisconsin, which will connect to the bridge, are on schedule and nearly completed.

Wednesday's announcement said the state transportation agencies would continue to work with the general contractor, Lunda/Ames Joint Venture, to finish the bridge "in the most efficient and cost-effective manner possible" with the goal of saving money and reducing construction time. It added that the state agencies "at this time are not considering legal action against the contractor."

The bridge portion of the project has faced "a variety of challenges," MnDOT said, including:

• A workforce shortage due to the improved regional economy, which made it difficult to find enough skilled and experienced workers.

• Equipment failures, including a crane that broke down at the Grey Cloud Island casting yard, near Cottage Grove, causing delays lasting from a day to a week. In July, a "segment lifter" quit working on the bridge's Pier 9, causing a weeklong delay. "Much of this specialized equipment is unique to this project," MnDOT said.

• Project complexity related to building a 3,200-foot bridge across the federally protected river.

• Material shortages, such as concrete forms needed to make the segments for the bridge, which delayed bridge construction five months in 2014. Only two U.S. companies make the forms; the selected firm's owner died and the company lost its lead engineer, which delayed fabrication.

• Weather issues also shortened the area's typical eight-month construction season. High water on the St. Croix in the spring of 2014 caused a two-week delay; progress was further slowed that year when winter arrived early. Mild weather this fall helped make up for some of the delays.

Wednesday's announcement didn't mention concerns raised last summer by the bridge's original metal fabricator, J&L Steel of Hudson, Wis. The company left the job after complaining that designs for steel framing were flawed and that this led to the same work being done over and over.

MnDOT's Beer said at the time that it was Lunda/Ames' responsibility to help subcontractors deal with "complexities and the learning curve" related to the bridge's design.

Kevin Giles • 651-925-5037