Legislation to protect the Highlands, which provides drinking water to more than half of New Jersey, faces its first crucial test Thursday, when the Senate and Assembly environment committees are scheduled to vote on it.

This land is irreplaceable. It must be protected. And it must be protected now, before rampant development forever harms one of New Jersey's greatest natural resources. The region's population is growing 50 percent faster than the statewide rate, and water usage could someday exceed local supply in some parts of the Highlands.

The legislation, based on the recommendations from a 19-member task force that gathered public input and developed a consensus on how to protect the 800,000-acre region and its water supply, is based on common sense: The panel identified a core area of just under 400,000 acres vital to protect the water supply, then recommended an array of measures to do that.

Those include a regional master plan to steer development away from the core area, financial aid for watershed towns that lose ratables, and tougher regulations to restrict building on steep slopes, near water supplies, or in forests.

Two Republican lawmakers from North Jersey, Sen. Henry McNamara of Wyckoff and Assemblyman John Rooney of Northvale, are on the environment committees, and both have expressed reservations about the legislation. They say one of their biggest concerns is the creation of a stable and dedicated funding source to buy key parcels and to compensate towns for ratables lost to watershed protection. Proponents of the bill say a funding plan, which could include a water tax, is in the works. They should work with the two legislators to allay their concerns.

The builders' lobby and other opponents claim the legislative process is moving forward far too rapidly. If anything, the exact opposite is true. Efforts to protect the Highlands and our drinking water are long overdue. For more than a decade, the state and federal governments have studied the region, but their recommendations on how to save it have gone nowhere. That's why it's so important the state act now, before it's too late.

It is vitally important that this legislation become law, and the best way to ensure that is to move quickly. The Senate and Assembly environment committees should approve the measure this week.