Seven years ago one of Honolulu’s last freshwater springs was in dire straits, an ancient natural gem buried and deteriorating under two stories of thick jungle behind a dilapidated house on coastal property in Kuliouou.

On Thursday county and state officials and East Honolulu community members celebrated the $2.6 million public acquisition of Kanewai Spring, permanently protecting a key source of freshwater for Maunalua Bay and opening up the lava tube-fed pool to conservation and education.

“When we started, it was just a dream,” said Chris Cramer, president of the Maunalua Fishpond Heritage Center and one of the first to rediscover the spring and help bring it back to life. “There are a lot of emotions today.”

On Thursday, the roughly 1,000-square-foot pool was spectacular, sparkling with crystal clear water and teeming with fish, the result of thousands of hours of volunteer labor under the direction of the center.

The purchase comes after the state Department of Land and Natural Resources Legacy Land Conservation Program granted $1.3 million and the city’s Clean Water and Natural Land Program contributed $1 million. Local foundations and donors raised $350,000 for a sale engineered by the Trust for Public Lands.

The land is now permanently protected through a conservation easement with binding restrictions that will be enforced by the city and monitored by area nonprofit Livable Hawai‘i Kai Hui.

Under the agreement, Maunalua Fishpond Heritage Center will continue to oversee the land, encouraging Hawaiian cultural practices and hosting regular volunteer work days for schools and the community.

Kanewai is believed to have once been a freshwater source for inhabitants of ancient caves nearby, and the water is key to supporting the fresh-to-saltwater life cycle of aquatic native species by flowing into Kanewai Fishpond, then into the Paiko Lagoon Wildlife Sanctuary and then into Maunalua Bay.

The spring is in the backyard of a Kalanianaole Highway estate that includes a 3,300-square-foot home built in 1948. The home was once owned by the infamous Ron Rewald, a con man who swindled $22 million from more than 400 local investors but lost the home in 1985 after he went to prison.

The home, obscured from the highway by a high wall, remained unoccupied and deteriorating until 2010, when the Maunalua Fishpond Heritage Center asked the new landowner, Rikuo Corp., if it could restore the murky and stagnant waters of the forgotten spring.

“This whole place was covered with what some people would say were weeds. It was so overgrown it was up to the roof,” Keolani Noa recalled Thursday. “To see it like this (now) is just amazing.”

Once the spring and native vegetation were restored, however, investors began expressing interest in buying the property, hoping to subdivide, build houses and turn the spring into a private swimming hole.

Syanne Sasekhi, Rikuo’s property coordinator, said the company probably could have sold the property for twice as much as it eventually did. But by that time, she said, Cramer and others with the nonprofit had already taught company officials how special the natural feature was.

“They waited for us for years — even when multiple offers continued to come in,” said Laura Kaakua, native lands project manager with the Trust for Public Land. “We have not worked with a corporation like this before, so we can’t thank the Rikuo Corp. enough for making this happen.”

Among those at Thursday’s event was 13-year-old Ella Gibson, who visited the spring last year as part of a school project. She said she anticipates returning to work every third Saturday of the month.

“It’s special and it’s our kuleana, our responsibility, to protect it,” she said. “It’s what our kupuna, our ancestors, would have wanted.”