WATERSHEDS PROVIDE OUR HEALTHY WATERSHEDS ENSURE OUR WATER FOR LIFE WATER FOR LIFE What is a Watershed? Shrubs and dense vegetation block the wind, Hawaiian watershed forests are unique and fragile environments, and need our special care to flourish. Their which draws moisture from the ground, and uniqueness sustains the natural cycle of water, from rain falling on forested lands, captured by trees and plants, A watershed is an area of land enclosed by moun- stabilize the soil, allowing the water to seep into and eventually absorbed by the ground to seep into our ground water supplies. tain ridges that catches and collects rainwater to the earth to recharge the underground aquifer continually replenish ground water supplies. or to flow in streams to the ocean. What is a Healthy Watershed? Sub-canopy Trees and Shrubs The Board of Water Supply (BWS) pumps water Our Hawaiian rain forests from the underground aquifer to meet the daily are highly effective at cap- Raindrops and condensa- demands for water by O‘ahu residents. turing water. Each stratum tion filter through the of plant life within the leaves of the upper canopy and fall on the Kopiko¯ (Psychotria sp.) Where are Watersheds Located? forest serves a purpose, Multi-layered forest and collectively they form shorter trees and shrubs Look to the mountains. The Ko‘olau Range – from a multi-layered forest that soaks up rainfall and below. Some flow along the North Shore, along the Windward coast, the retains moisture in the ground and streams. Trees, leaf stems to seep into the backdrop for metropolitan Honolulu, and along shrubs, grasses, and other vegetation are integral ground. The dense short- the Central O‘ahu er vegetation keeps the air Hahai no ka ua i ka ulula‘au¯ – Rains always follow the forest. parts of a healthy watershed. (Ancient Hawaiian proverb) plains in the east; near the ground saturated Hesperomannia arbuscula O‘ahu’s and the Wai‘anae Watershed Areas and slows evaporation Here on O‘ahu, water from the ocean is heated Emergent Trees Range – along the from this layer of plants. by the sun and is blown in-land by trade winds. These trees are the first Central O‘ahu As the moisture-laden air approaches the high to receive the rain. Their Understory plains on the west mountain ranges, it rises, cools and condenses, branches and leaves Ferns and low shrubs and the Leeward which causes rain on the island. emerge from the forest absorb water falling from coast; shelter our Koa (Acacia koa) The Wai‘anae Range in the west and cover and intercept the tall trees and also O‘ahu’s watershed can Hawaiian rain the Ko‘olau Range in the east shelter rainfall and moisture from the air. In some cases, cushion the soil from the also be described as forests. O‘ahu’s Hawaiian watershed forests. they produce fog drip. Water runs from the leaves, impact of water dripping a Hawaiian rain forest, Palapalai (Microlepia strigosa) down branches, to plants near the ground. from leaves and branches. which captures and saves large amounts Who is Responsible for the Canopy Trees Watershed? Ground Cover of water. Tall trees These tall trees shape the canopy skyline of the Plants like moss and shade other trees and Hawaiian forest The State Department of Land and Natural forest and receive most of the rain and condensa- grass form a spongy, plant life from the sun Resources and the BWS are the governmental tion. Water drips through porous plant layer just and slows the rain as it falls toward the ground. agencies entrusted with the protection and care the trees and runs down above the soil. They Although the trees themselves are nurtured by of O‘ahu’s watersheds. Because the watershed the branches to the reduce evaporation from Elaphoglossum fern water, the trees help to reduce the amount of rain- benefits everyone, we are all stewards of the trunk, where its momen- the ground and slow fall lost through evaporation and transpiration in watershed and share the responsibility to safe- tum slows as it moves runoff, preventing soil the forest. guard these forested lands. over the bark. ‘Ohi‘a¯ (Metrosideros polymorpha) erosion. PROTECTING OUR WATERSHEDS GETTING WATERSHEDS NEED OUR HELP INVOLVED What Threatens the Watershed? You can help to protect and restore our Hawaiian For more information on how you can join the rain forests and watersheds by working with effort to protect our watersheds and forests, PROTECTING OUR For more than a million others in the community, participating in on-going please contact: years, native Hawaiian protection programs, and educating others of the birds, animals and in- Board of Water Supply WATERSHEDS importance of our watersheds. No effort is too sects played an integral (808) 748-5936 or 748-5940 small, and every effort will help to protect this part of a healthy water- fragile environment. State Department of Land and shed by pollinating and Dense vegetation and flowing Natural Resources Here are ways that you can spreading the seeds of streams nurture O‘ahu’s water- (808) 587-0166 plants. However, foreign sheds. help: plants and animals introduced by Western settle- • Support the enforcement Board of Water Supply partnerships include: ment threaten our Hawaiian rain forest by destroy- of existing laws and •Ko‘olau Mountain Watershed Partnership ing native plants and animals and invading the agriculture quarantine • Makua Implementation Team environment, and reduce the watershed’s ability to prevent the introduction •Mohala¯ I Ka Wai to catch and retain water. • Punalu‘u Watershed Alliance of foreign plants and By protecting our watersheds, animals in the watershed. •Wai‘anae Kai Community Forest Partnership The following are examples of non-native plants and Punalu‘u Watershed the watersheds will continue to sustain the animals that have invaded our Hawaiian forest: Alliance – Looking at a • Participate in projects that •Waihe‘e Ahupua‘a Initiative (WAI) natural cycle of water and support our stream gage. Miconia, Christmas remove invasive plants and need for a reliable water supply. Berry, Guava, and animals to allow native Hawaiian plants and Clidemia are examples animal populations to recover areas where of plants that displace they were displaced. native forest plants and • Join community kill understory growth, watershed partner- Strawberry guava (Psidium causing erosion of ships, which plan and Waihe‘e Ahupua‘a Initiative – cattleianum) Children planting native plants. watershed land. organize activities for Pigs, goats, and sheep watershed protection, Mohala¯ I Ka Wai – Wai‘anae High School Koli‘i (Trematolobelia macro- eat and uproot native restoration, and students installing stachys) plants, creating soil education. Makaha stream gage. erosion and space for • Conserve water every- Wai‘anae Kai Community Photo by T. Yoza foreign plants to grow. day, all year long. Wild pigs uproot native plants Forest Partnership – Installa- and the soil, disrupting the Introduced birds like the Water conservation tion of erosion control material. delicate balance of the water- Bulbul compete for food reduces the need to Board of Water Supply shed environment. and harbor diseases use ground water that City & County of Honolulu transmitted via mosquitoes, reducing or completely is essential for healthy Wiliwili (Erythrina sandwicensis) 630 South Beretania Street destroying remaining native bird and insect popula- watershed forests and www.boardofwatersupply.com Honolulu, Hawaii 96843 tions and driving them to extinction. stream ecosystems. bws/rev05 www.boardofwatersupply.com