A plan to rebuild the five footbridges at scenic Great Falls, which were destroyed by Hurricane Agnes in 1972, is in jeopardy unless the public contributes the final $20,000 for the project, officials said yesterday.

Although nearly $500,000 in federal, state and local money has been committed to rebuilding the bridges, much of that money "will disappear" if the last $20,000 is not in hand by the end of March, Montgomery County Council member William E. Hanna Jr. (D-District 3) said at a news conference in Rockville.

"You're either going to be walking across the bridges this year, or in all likelihood, you'll never walk across those bridges again," said Hanna, who was joined in his appeal by Rep. Constance A. Morella (R-Md.).

The bridges, which were built more than 100 years ago, enabled visitors at the C&O Canal National Historical Park to reach a vantage point on Olmstead Island that offered the only complete view of the cascading waters. For the last five years, Hanna has led an effort to restore the bridges and the view from the Maryland shore, which he described as "the most spectacular on the East Coast."

The organizers have raised $200,000 from Maryland, $100,000 each from the federal government and Montgomery County, and $35,000 from the private sector. Some donations have come in accompanied by notes from people who remember wedding engagements and other special moments that took place on the old bridges.

"I figured if 4,000 people give $5 . . . or if 20,000 people will just give $1, the bridges will be built," Morella said.

Otherwise, Hanna and Morella said, the grants earmarked for the project will expire and, given the current uncertain economy, it is unlikely that such appropriations would be available again.

"I just thought, here was a challenge everybody seemed to be in favor of," Hanna said. "It would be awful for it not to happen for lack of $20,000."