Pu’u o ‘Ehu Hillside History
After the melting of the last ice age, the Hāmākua site was part of a wide shallow marine bay with abundant coral and fish. About 1,500 years ago the ocean shoreline returned to near the present level and a large sand bar (now Kailua town) separated the site from the ocean. Hāmākua was a narrow flat area connecting two large brackish lagoons with abundant fish that received fresh water from Muanawili watershed streams and exchanged of salt water with the ocean. Hāmākua stream flowed through the site from one lagoon (Kawainui) to the other (Kaʻelepulu). Pollen records from core samples taken from the hillside above Kawainui show that the area had been a lowland palm forest, and the most abundant species was Loulu Palm.
Around 1,000 years ago the Hawaiians settled the area around the lagoons. Kawainui was the largest cultivated freshwater fishpond on Oʻahu and provided abundant fish, in addition to that caught in the nearby ocean. Farmers grew kalo (taro) in the irrigated lo‘i (fields) along the streams from the Maunawili watershed and along the edges of the fishponds. They set up 'auwai (irrigation ditches) and cultivated dryland kalo, mulberry, arrowroot, banana, sweet potato, sugarcane and tobacco on the edges of the marsh. Along Hāmākua stream specifically, they grew taro in narrow patches. The taro was watered and fish were harvested using three dams. This use continued for at least 700 years, and became more intense as the population grew. Within the first few hundred years much of the endemic forest and plants were cleared.
Kawainui means the "large flow of fresh water" and Kaʻelepulu means the "moist blackness." The Hawaiians considered Kawainui to be male and Kaʻelepulu to be female. Kawainui was very important as evidenced by multiple Heiau (sacred sites marked by stone platforms) on its borders and its place in the many chants and legends. The intersection of (Wai'auia) on the Kawainui side was considered to have great mana (power) and ali'i (chiefs) from this area had the highest status.
Private ownership and landscape changes
In the mid 1850s land in Hawaii was redistributed under the "Great Mahele" and passed from traditional use to private leases. At the same time, there was a dramatic decline in the Hawaiian population due to epidemics, which resulted in many fishponds falling into disrepair. The taro fields shifted to rice from the 1880s to 1920s, but then the area was taken over by cattle ranching. Stream water was diverted to sugar can plantations. Water from Kaʻelepulu pond was pumped to water a sugar plantation in Waimanalo starting in 1924. These uses, along with increased building, led to sedimentation of the marshes. Introduced grasses took over.
New housing developments in Kailua needed protection from flooding so starting in the 1950s a levee was built and later extended which separated Kawainui from the development, but also separated it from Hāmākua marsh. Oneawa canal connecting Kawainui to the ocean was also built. In 1956 Kawainui was drained to use as pastureland.
In 1960 Kaʻelepulu Pond was diminished and most of the surrounding marsh was filled and drained through a canal to Kailua Beach Park in order to build the housing development of Enchanted Lakes. 5.8 acres of private wetland remain from an original 90 acres. The pond was reduced from 190 to 79 acres.
What was once the Hāmākua stream is now a body of water that runs along the other side of the levee in Kawainui Marsh, with no connection to the Marsh or to the Oneawa canal on one end, and connects to the Kaʻelepulu canal between Enchanted Lake and Kailua Beach Park. The canal is usually separated from the ocean by a sand bar, but the sand bar is occasionally dug up to allow water to flow and clean out Enchanted Lake. When this happens, water also flows into Hāmākua.
Environmental and Cultural preservation
Kawainui Attempts to develop Kawainui area as a shopping center in the 1960s were thwarted by the Lani-Kailua Outdoor circle. 1987 the Kailua Hawaiian Civic club became curators of the Ulupo Heiau and cleared the area. In 1996 another group started restoring the habitat around Nā Pōhaku O Hauwahine, which now features over 80 endangered native plants. Due to their efforts, the area was declared a Ramsar Wetland of International Importance (2005) and a State Wildlife Sanctuary (2007).
Hāmākua In 1989 the Castle Estate became sole owner to the Pu'u o ʻEhu watershed above Hāmākua, having bought out part-owner Iolani School. 1992 Kaneohe Ranch applied unsuccessfully for zoning changes to develop a retirement community with 4 storied apartment buildings on the Pu'u o ʻEhu Hillside, the watershed rising above Hāmākua Marsh. Around the same time, they funded habitat restoration of the wetland itself by Ducks Unlimited, and then in 1995 donated the 23 acre Hāmākua wetland to the State Department of Land and Natural Resources. This area was declared a State Wildlife Sanctuary in 1997. In 2013 the State bought the 67 acre hillside to further protect the Wildlife Sanctuary.
Invasive plants crowd out native species and fill in open water, shallow water, and mudflats the waterbirds need. Much restoration has been done, and the wetland areas in Hāmākua have indigenous Hawaiian plants such as bullrush (Bolboschoenus maritimus - paludosus), water hyssop (Bacopa Monniere), ditchgrass (Ruppia maritima) and some akulikuli (Sesuvium portalucastrum). Invasive plants such as Pickleweed, Fleabane and Red Mangrove grow on the edges of the wet area. Invasive plants such as Kiawe, Christmas berry, fiddlewood, koa haole, Chinese Banyan, and alien grasses such as California grass dominate the surrounding dry area.
Habitat loss due to land use changes and introduction of invasive plants, as well as hunting by humans and by invasive animals such as rats and mongoose, have threatened native waterbird populations. All of Hawaii's endemic rails, flightless geese, and one type of ibis have become extinct. All six surviving species of endemic waterbirds are endangered, with populations of less than 3,000. Of these, all but the Laysan duck and Nene are found in Hāmākua.
Nearly 60 species of migratory ducks, geese and shorebirds have used the Hawaiian Islands during the winter. These waterbirds have also shown a marked decline, from tens of thousands in the 1950s to only a few thousand in the 1990s.
Hawaiian coot (Fulica alai) or ʻalae keʻo keʻo is black with a prominent white frontal shield and beak. These birds are secretive and build floating nests with aquatic vegetation anchored to stationary vegetation. In 2010, the US Fish and Wildlife estimated the population to be 1,500 in the winter and 2,000 in the summer. These birds have big feet with flaps that extend on either side of their toes, which serve the same function as ducks webbed feet.
Hawaiian moorhen (Gallinula chloropus sandvicensis) or ʻalae ʻula is mostly black with a prominent red frontal shield and beak with a yellow tip. The name means "burnt forehead" and they were keepers of fire in the Hawaiian religion. Found only on Oʻahu and Kauai, the population is increasing but US Fish and Wildlife 2011 counts averaged 287.
Hawaiian stilt (Himantopus mexicanus knudseni) or ae'o kukuluao called "one standing high" due to the bird's long pink legs. It is black on top, white on the underside and has a long, thin black beak. It is endangered with population estimates averaging 1,500 ten years ago.
Hawaiian duck (Anas wyvilliana) or koloa maoli was eliminated from all islands but the Big Island, and 326 captive ducks were reintroduced to Oahu starting in 1958 over a period of 24 years. The biggest threat now is that it is interbreeding with male mallard ducks and the offspring are hybrids. The koloa have similar while and brown mottled coloring as female mallards and can be hard to distinguish at a distance.
Black-Crowned Night Heron (Nycticorax nycticorax hoactli) or ʻaukuʻ is found all over the world and is indigenous to the Hawaiian Islands. It is not endangered. Unlike the other subspecies which are active mostly at night, the subspecies in Hawaii is active during the day.
Other water birds that are not native or endangered, but may be seen at the Marsh are:
Cattle Egret, Pacific Golden-Plover, Ruddy Turnstone, Wandering Tattler, and Sanderling.