Project aims to restore gulch, buffer runoff
Organizers expand efforts to bring back vegetation in Keokea Gulch
Work to reestablish the riparian corridor — the natural flora and fauna along waterways — in Keokea Gulch within Hapapa watershed is underway to buffer runoff into streams and the North Kihei coastline.
Many areas in South Maui are prone to flooding during heavy rainfall and without watershed management and repairs, sediment and debris can flow straight down the mountain and into the ocean, said Katie Woodbury, an ecologist with Maui Environmental Consulting.
This is why MEC, Haleakala Ranch and the Central Maui Soil and Water Conservation District, with funding from the state Department of Health, Clean Water Branch, have been working on the second phase of the 7.4-acre Keokea Gulch Riparian Corridor Rehabilitation Project.
A riparian corridor is the vegetation near a river, stream, wetland, lake or other natural body of water. The project is located on Haleakala Ranch, about a half-mile mauka of Piilani Highway and just north of the Bayer agricultural operation in Kihei.
The purpose of this continued rehabilitation will be to “improve water quality within Keokea Gulch, plant and promote native dryland forest, reduce the amount of wastewater entering injection wells, provide opportunities for cultural experiences, community outreach and involvement, and to educate the community on native dryland forest ecosystems and habitats,” said Woodbury.
Keokea Gulch begins around 2,300 feet, just below Kula Highway and Keokea Park and winds down into Laie Wetland, just south of Lipoa Street, and ultimately into the ocean.
Based on water quality data by nonprofit Hui O Ka Wai Ola, the coastal waters associated with Keokea Gulch do not meet water quality standards for turbidity, total nitrogen, nitrate and nitrite, and ammonia.
“Riparian buffers along gulches and gullies prevent sediment-laden sheet flow from entering streams and discharging into nearshore coastal waters,” Woodbury said last week. “They also offer important habitat for native flora and fauna.”
Fixing the corridor will help lock in soils to mitigate stormwater impacts to the coastal waters of Kihei, especially during flooding events. Native forest planted within the corridor will also provide “critical habitat” for native plants and animals, as well as create opportunities for cultural and educational experiences for the community, she added.
Distributing R-1 water to the landscape for irrigation, which is also part of the project, keeps the wastewater from entering injection wells and allows for natural filtration before the wastewater is added to groundwater recharge.
During Phase I, which began in 2020 and was completed in January, feral ungulate fencing was installed to fully enclose and secure the perimeter. Then, R-1 irrigation infrastructure was installed, including 6,000 feet of dripline and about 2,000 drip emitters. The phase concluded with the planting of about 2,000 native dryland plants, which were watered with one gallon of R-1 water per day.
Continued monitoring is conducted to address plant mortality and to ensure the fencing and irrigation infrastructure remains functional, Woodbury said.
Due to the success of Phase I of the project, agencies expanded their coverage from the original 5.8 acres.
Phase II will be completed in March.
Phase I of the Keokea Riparian Rehabilitation Project was funded with $50,000 from DOH’s Clean Water Branch while the second part has received an additional $50,000.
Depending on how everything goes, there is potential for a third phase, or expansion of this project, as part of a mauka-to-makai dryland native forest rehabilitation effort.
Woodbury said that the team hopes that the riparian corridor will serve as a demonstration that nature-based solutions could help “address sediment runoff during flooding events islandwide.”
* Dakota Grossman can be reached at firstname.lastname@example.org.