Guam is America’s unsinkable aircraft carrier in the South Pacific, the fulcrum of the fabled Pacific “pivot.” It’s also kind of a mess.

With a GDP per capita less than a third the US average, an earthquake-damaged harbor, geriatric generators that black out the entire island roughly twice a year, drinking water periodically contaminated with sewage, a fire department with three working ambulances for a population of 160,000, and a police department so short-staffed it’s started deputizing unpaid civilians, according to a Government Accountability Office report due out today, Guam is closer to the Third World than to California economically as well as geographically.

That’s not just a development problem, it’s a national security issue. The Defense Department, which already owns more than a quarter of the island, plans on bringing in 5,000 more Marines and their estimated 1,300 dependents. DoD and GAO agree that the island’s infrastructure isn’t ready to receive them. What they disagree on is the cost to get it ready. The last three defense budgets requested, all told, $400 million for public infrastructure in Guam over 2012-2014, with more costs to come, but GAO doubts that that’s all necessary.

There are two big problems here, one that’s merely difficult to fix and the other nigh-impossible. The first is that the Pentagon’s still rewriting its Guam plan. The original goal was to relocate 8,600 Marines and 9,000 dependents from Okinawa to Guam by 2014, but disagreements over cost-sharing with the Japanese led the Defense Department to scale the move down to 5,000 Marines and 1,300 dependents. (Mathematically minded readers will notice that the Marine-to-dependent ratio in those two plans is radically different: My guess is this is because the current plan includes a higher percentage of young, unmarried Marine Corps riflemen).

That’s a 64 percent reduction in the number of people moving, but you can’t just cut the cost estimates by 64 percent and call it a day. A smaller force gives you more options about where to put it, such as US bases on the island that generate their own clean water, which could bring the needed infrastructure investments down more than 64 percent. But some costs are fixed – assuming that you decide to do them at all– such as upgrading water treatment plants.

That kind of costs brings us to the second, almost insoluble problem: How do you disentangle what’s needed purely to support the military– i.e. what Congress feels the Pentagon should pay for – from what’s needed by the civilian population? You can’t even draw a neat line between the two groups, because adding more Marines and their families also requires adding more civilian contractors who will work on base but never live there.

The relocation would also mean a temporary upsurge in construction workers, many of them from off the island, and, besides all the other public infrastructure the influx would require, Guamanian officials say they lack the health labs to test the newcomers for communicable diseases. Then you get into messy issues like landfill sites: The main Air Force and Navy bases have almost filled theirs up and are starting to send their trash, for a fee, to Guam’s waste disposal site, which by the way is in court-ordered receivership for environmental violations.

Congress has been deeply skeptical of the Pentagon’s cost estimates and Japan’s pledged contributions, so it keeps legislating restrictions on what the Defense Department can spend to move forces from Okinawa to Guam, leading to what one thinktank study called a “logjam.” As Congress’s accountant/attack dog, the GAO has challenged DoD on costs in the past, and the report due out today is just the latest installment in a long and dreary story.

So what does the GAO study (which we got in advance) actually recommend? The report’s title, as usual, is little help: “Further Analysis Needed to Identify Guam’s Public Infrastructure Requirements and Costs for DoD’s Realignment Plan.” (Pro tip: GAO always thinks “further analysis is needed.” If your house was on fire and you were trying to get out, GAO would tell you to first make sure that your escape plan met best practices and that you had perfected your knowledge-based systems analysis. In this case, GAO wants the Defense Department to revise its estimates for Guam – which the Pentagon is doing – before it asks for any more money and to write “an integrated master plan” for all the forces reshuffling around the Pacific – which the Pentagon is not doing.

That’s precisely the kind of long-term planning that the last two years of sequestration, government shutdown, and general legislative chaos have made impossible. Now that the budget deal has – we hope – stabilized the situation for the next two years, maybe everyone can get back to business.

Updated Wednesday to add link to now-published report.