The US Navy's plan to repair its public shipyards is expected to cost billions more and take decades longer than originally planned, according to a new government watchdog report.

The Shipyard Infrastructure Optimization Program is intended to fix poor conditions at the Navy's four public shipyards, which maintain the fleet's nuclear-powered submarines and aircraft carriers.

However, unplanned costs and newly identified risks have dramatically expanded the project's scope, leading the report authors to recommend that Congress require the Navy to provide annual updates on its progress.

Last week, the Government Accountability Office, a congressional watchdog, released a report documenting problems with the program, writing that it "will surpass $200 billion and take over 50 more years to execute" based on GAO analysis.

The report added that "developing the plans and cost estimates to rebuild the Navy's four public shipyards has taken the Navy years longer — and will cost much more — than originally anticipated due to multiple challenges and changes involved in the program."

The Navy has four public shipyards: Norfolk Naval Shipyard in Virginia, Pearl Harbor Naval Shipyard in Hawaii, Portsmouth Naval Shipyard in Maine, and Puget Sound Naval Shipyard in Washington. Poor conditions have left the yards unable to keep up with maintenance demands, leading to backlogs.

USS Boise, a Los Angeles-class submarine that ultimately spent roughly a decade sidelined by maintenance delays before finally being retired, is a particularly well-known example of these challenges.

Problems with the yards, as well as the need to upgrade capabilities for future vessels, prompted the Navy to initiate the optimization plan in 2018, but the service "underestimated the time needed" and "did not fully account for the many challenges, uncertainties, and complex analyses needed to sufficiently plan for an endeavor of SIOP's magnitude," the GAO report said.

One such issue that arose was the vulnerability of structures at Puget Sound to potential seismic activity. The GAO said "since 2023, the Navy has identified over $1 billion in needed facility retrofits and new construction to mitigate newly assessed seismic risks" at the yard. Many of the facilities in the four public yards were built between 80 and 120 years ago and have deteriorated due to long-deferred maintenance. This has led to unexpected or additional work needs, the report said.

And while these shipyards are being upgraded, they are also still active, creating other issues. In one example, safety risks were found in failing buildings at Norfolk, requiring extensive repair projects to the facilities, including one building that may eventually be demolished but is currently used for ship maintenance.

In its new report, the GAO made four recommendations, including that Congress should require the Navy to "annually report consolidated, standardized status updates" on the program's cost and schedule. The remaining recommendations include future reviews of requirements and resources, as well as documenting the roles and responsibilities of organizations involved in the program.

The GAO said the Navy agreed with the recommendations and outlined steps to implement them. The Navy did not respond to Business Insider's request for comment on the report.