There is progress being made on a plan to insulate Oahu’s water supply from the risk of contamination through the historically leaky Red Hill fuel tanks, officials say.

Progress is better than no progress, but the recovery plan now in the works is shaping up too slowly and should be made more — in a word — watertight.

U.S. Environmental Protection Agency officials addressed a public meeting Monday and assured the crowd that the U.S. Navy, custodians of the underground storage facility in question, is making headway in its plan to reinforce the containment system.

But environmentalists and others, including the manager and chief engineer of the Honolulu Board of Water Supply (BOWS), were not mollified. They make the more convincing case for accelerating the pace of planning and development of a long-term fix, and that vigilance over the purity of the water resources nestled close to the tanks should be more robust.

Many residents were unaware that the Red Hill Bulk Fuel Storage Facility existed until it burst into public consciousness 2-1/2 years ago. That’s when 27,000 gallons of jet fuel leaked from one of 20 tanks into a rocky zone below.

The Navy maintained that the leaked fuel has not contaminated drinking water. Even so, the accident led to a negotiated agreement involving the EPA and the state Department of Health, setting into motion efforts to avoid future leaks while averting the payment of sizable fines.

That accord, the Administrative Order on Consent (AOC), was finalized last September, and discussions began about the types of reinforcements that would be deemed sufficient protection. The goal of the plan is to implement fixes over 22 years as the facility remains in operation.

BOWS Manager Ernie Lau earlier in June sent a 17-page letter detailing the plan’s shortcomings to the EPA. Among numerous criticisms, Lau said the Navy is ignoring scientific data that could assist with tracking the jet fuel that drained from Tank 5 in 2014. Lau rightly urged the Health Department and EPA to compel the Navy to provide this data.

What makes it all the more distressing is that the federal officials are easing up on monitoring rules, indicating that they would require the Navy to test the water for only 12 compounds. This is puzzling, given that the Navy already had agreed to test for the same 64 compounds on which it has collected quarterly samples since 2005.

Steve Linder of the EPA said the remaining 52 compounds generally were not detected in the samples because they are not found in the fuel stored at Red Hill.

Some middle ground ought to be found here. Record-keeping at the facility over the decades has been anything but consistent, so it would seem wise to err on the side of caution and broaden the search for contaminants.

There have been some encouraging signs. The installation of a “tank within a tank” design as the optimal way to reduce the risk of future leaks has found favor among the planners — a high standard that the water board has rightly insisted the Navy needs to maintain.

Consider what’s at stake. The jet fuel storage tanks sit on a ridge between Moanalua and Halawa valleys; the lowest of the 20 is positioned about 100 feet above the aquifer that supplies about one-quarter of the water needed by Oahu’s population.

Spending the federal dollars required for comprehensive testing would seem a prudent investment in the protection of such a precious resource.