Suffolk County has a new master plan, its first in 45 years. It includes lots of sound ideas for the county's future, many touted previously by County Executive Steve Bellone. Others are more out-of-the-box -- such as an echo of this page's call to study the feasibility of a deepwater port to provide an alternate way to move people and goods on and off Long Island.

But the plan won't be worth much if it ends up sitting on a dusty shelf. The last one was drawn up in 1970 by master planner Lee Koppelman. And with one glaring exception, it succeeded because it was used as an active blueprint.

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That plan pushed, among other things, the preservation of open space, a concept embraced by many leaders who followed. And it worked. From 1998 through 2011, no county in the United States spent more on preserving land than Suffolk, and now some 20 percent of the county has been set aside for open space, recreation and parkland.

But the old plan also called for more affordable housing, a plea largely rejected by towns and villages that have control over zoning. The result: Koppelman's still-needed call is repeated in the new plan, with an appeal to build such housing in neighborhoods with good schools. And it underscores the urgency by noting the continued rise of rental and home prices, and that about one-third of Long Island households pay more than 30 percent of their income for housing.

Suffolk has changed a lot in 45 years. It now has more people than 11 states, but its infrastructure is aging, its economy is lagging, and its environment is under threat. The new plan's prescriptions won't work if they're not put into action. Let's make this plan a real guide, so future generations aren't looking back and lamenting what might have been.