A fire burning in a watershed and wildlife preserve above Waianae has burned about 2,000 acres, including 1,000 acres of the Waianae Kai Forest Reserve, the Department of Land and Natural Resources said today.

DNLR firefighters are hoping to keep the fire west of the Kumaipo trail and ridge top, and from further damaging the watershed, which helps provides drinking water for the Waianae Coast.

Three helicopters contracted by the department and an Army helicopter are dropping water on the blaze in steep terrain in the Waianae mountains.

The U.S. Army Garrison Hawaii is providing a helicopter because endangered plants that the Army manages are at risk, said Dan Dennison, a spokesman for the DNLR.

The reserve is a “critical habitat for rare plants and invertebrates such as land snails and picture wing flies,” Dennision said in a news release.

Rains and light winds last night helped efforts to contain the fire, he said.

But winds were expected to pick up today.

Crews were able to use a fire break created by a cement road maintained by the Honolulu Board of Water Supply and a “green break” of native plants that the West Waianae Watershed Partnership has been planting for the past three years.

“Some of the plants were singed but, by and large, most of this area was not burned,” Dennison said.

The blaze broke out Thursday night. Fed by gusty winds on Friday, it threatened homes and engulfed a used auto parts dealer, torching hundreds of cars on the lot. But Honolulu Fire Department personnel managed to fight it back.

With the fire contained to the forest reserve, DLNR’s Division of Forestry and Wildlife took the lead today. The Honolulu Fire Department shifted to a support role, offering its tender vehicle for refueling and maintenance of helicopters and a water tank, but not deploying its own firefighters on the ground.

DLNR spokeswoman Deborah Ward said her department sent 16 ground personnel and contracted helicopters to fight the fire this morning in the lower part of the Waianae Kai Forest Reserve.

“It’s steep terrain, but it’s not in the upper areas of the Waianae mountains,” Ward said this morning. “As of yet, it’s not likely that native or endangered species are being affected, but we’ll have to see what happens today.”

The affected area has dense guinea grass, haole koa, silk oak and other non-native species.

Meanwhile, the Fire Department reported that the lower, populated section of Waianae Valley was safe.

“The lower area is secured,” said Capt. David Jenkins, public information officer for the Honolulu Fire Department. “It’s totally contained. Everything down in the valley is OK.”

“If there is a need or there are concerns, people can still call the Honolulu Fire Department,” he added. “We will go out and assess and do what’s needed to keep the community safe.”

Jenkins said investigators have not determined what first triggered the fire, but the weather whipped it up.

“The winds were a definite major factor in regards to this,” he said. “It caused the fire to quickly spread and hampered fire-fighting efforts in the initial stages of fighting the fire.”

The last major fire in the upper valley are burned 1,200 acres in June 2012, including 400 acres of forest reserve.