Yesterday, at 10:49 a.m., the Harold L. Lyon Arboretum in Manoa Valley wrestled with a problem it hasn't had on a Saturday in nearly four years:

Traffic congestion in the parking lot.

With the facility's 30 parking stalls filled and extra cars double parked, Arboretum director Christopher Dunn scrambled to move his own vehicle to an adjacent grassy area so visitors Grace Furuya and her father, Herbert, of Kaimuki, could take his space.

"I didn't think congestion would be an issue today at all," Dunn said with a laugh after the parking moment. "But I'm delighted and pleasantly surprised. It's better to have more than fewer. We're in a good place now."

The incident highlighted what Dunn and others hope will be the dawn of new and better times for the University of Hawai'i's 90-year-old arboretum after one of its most challenging periods.

In August 2004, following months of controversy, the university shut down the 193.5-acre rainforest citing "significant health and safety issues." The facility was not compliant with the Americans with Disabilities Act, the university said, and some of its buildings needed to be renovated or torn down.

The Legislature approved nearly $3 million in 2005 to make much-needed renovations to the facilities, and the arboretum reopened on a limited basis in January 2005 — but its educational and commercial activities remained closed for months more.

The arboretum was turned over to UH in 1953 and conducts critical research on endangered and rare native plants. Nearly 4,000 schoolchildren made their way through the arboretum's educational facilities each year before its closure. It is the only university arboretum in the United States that is in a tropical rainforest.

Yesterday marked the first day the arboretum has been back on its original Monday-through-Saturday schedule since the shutdown.

Research associate and head groundskeeper Ray Baker, who has been with the arboretum for 36 years, said it was a relief to have the park open full-time again.

"The arboretum shut down totally for four months in 2004," he said. "Then when it reopened, we still couldn't have any public activities because the main building was still not handicapped-accessible. Just a month or two ago, they finished making it handicapped-accessible, and we worked out a system where somebody could man the gift shop — and that's why today's the first day."

Dunn said the No. 1 question people had asked was, "Why aren't you open when I can bring my family?"

He personally greeted Robin and Janice Rogers of Hawai'i Kai, who exemplified folks who otherwise would not have been able to enjoy the park. They were visiting the arboretum for the first time, they said, because it was now open on a Saturday.

"We were looking for someplace different where we could go walking on weekends," said Robin Rogers as he perused a layout of the park. "We're going to look at the map, we're going to see how far the falls are, and we'll probably go up to this rain shelter up in the Fern Valley."

Dunn, who took over as director 14 months ago, said he was eager for the park to fulfill its mission to inspire and educate the public six days a week. He said the park's extended weekday hours would also provide greater community access. And he was obviously pleased by the progress of the park's improvements.

"The visitors' center has been renovated and dressed up," he said. "We've fixed our greenhouse roof. We've completely demolished two of our buildings. One of them, when it's rebuilt, will be the children's educational center. And the other one will be the offices for all the grounds staff."

After their hike, Robin Rogers said he and his wife would be coming back.

"This was really refreshing," he said. "We're happy that it's open on Saturdays. If you work, it's kind of hard to visit the arboretum during the week."