At nearly 12, 000 acres, Pu’u Kukui Watershed Preserve is the largest private nature preserve in the state of Hawai’i, responsible for taking care of the most pristine watershed from mauka to ma kai of Mauna Kahālāwai on Mauiʻs West side. The unique biodiversity of the area is extremely rare and a wonder to see. This area is a vital water source for Mauiʻs community and one of the wettest spots on earth and is home to some of the rarest endangered flora and fauna in the islands. Over 300 native plant species can be found in the preserve; including nine plant species on the US Endangered Species List and Hawai’i’s only mammal species: the ‘Ope’a’pe’a or Hawaiian Hoary Bat and the ‘ilioholoikauaua or Hawaiian Monk Seal, both of which are endangered. The preserve hosts many native species, some in natural habitats as pristine as when the first Polynesians arrived on the islands about 1,500 years ago.

Pu’u Ku Kui serves as the source of both irrigation and potable water for Kapalua Resort, Kapala Farms, Maui Pineapple Co. and West Maui residents from Kapalua to Honokowai. Conservation endeavors include non-native invasive species control, weed control, monitoring, research and most importantly protecting rare species.