Watershed Based Projects to Address Stormwater Pollution and Flooding

Michael Reyes

Mālama Haleakalā Foundation

Maui Environmental Consulting, LLC

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Watershed Plans

• The Southwest Maui Watershed Plan, which encompasses the Hapapa, Wailea, and Moʻoloa Watersheds, both the Waikapū and Waiakoa Watersheds (collectively called the Maʻalaea Bay Watersheds Management Plan), and the Pohakea Watershed Plan have been approved by the EPA and Hawaii Department of Health. Implementation projects listed in these plans are eligible for federal 319 funding.

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• Approximately 100,700-acres spanning from McGregorʻs Point to Makena State Park are now covered by an approved watershed plan.

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• The Watershed Plans can be downloaded at Mauiwatershed.org

North Kihei Flooding

• Waiakoa Gulch and Keahuaiwi Gulch converge at the intersection of South and North Kihei Roads.
• Waiakoa discharges into the ocean.
• Keahuaiwi discharges into Kealia Pond via an undersized swale.

Axis Deer and Feral Ungulate Fencing

• Feral ungulates such as axis deer, goats, and pigs are devastating our watersheds. Specifically, axis deer are overgrazing pasture grasses and denuding entire landscapes.
• Kaonoulu, Haleakala, and Ulupalakua Ranches have been investing hundreds of thousands of dollars to install feral ungulate fencing throughout their lands.
• Fencing is quite expensive, with costs for materials and installation ranging from $26 to $30 a linear foot.

Existing and Planned�Feral Ungulate Fencing

• Additional fencing is needed to control axis deer.
• Currently, the ranches are able to conduct rotational grazing with their cattle herds, but without additional deer fencing,
• Axis deer herds are unchecked and destroy large swaths of land.

Axis Deer and Brown Water Events

• As deer overgraze, they leave the land bare of vegetation.
• During stormwater events, this bare land erodes and enters into gulches and streams where it eventually makes its way to the ocean.
• Once there, it smothers coral reefs.

In 2023, Malama Haleakala Foundation secured $400,000

from the State of Hawaii Department of Agriculture to place

additional feral ungulate fencing on Leeward Haleakala.

Reclaimed Wastewater (R-1)

• The Kihei Wastewater Reclamation Facility produces approximately 3.9 million gallons of R-1 Water per day. Of that, about 1.3 million gallons get reused. The remaining 2.6 million gallons is injected into the ground where is slowly makes its way to nearshore coastal waters.
• This water is high in nutrients, with hundreds of pounds of Nitrogen and Phosphorus being injected into the ground every day.

Current R-1 Projects��Keokea Riparian Rehabilitation

• The purpose of this rehabilitation project is 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.
• 3,000 native dryland forest plants were planted. The plants receive 1 gallon of R-1 water each day. The entire project utilizes 21,000 gallons of R-1 water each week.

Current R-1 Projects

Axis Deer Mitigation

The intent of this pilot project is to identify the best delivery

system to place large amounts of R-1 water on leeward

Haleakala to provide water for livestock forage while also

locking in soils denuded by axis deer. By relocating the R-1

water back onto the land and removing it from injection wells,

this project will have a significant impact on near shore water

quality and coral reef health.

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This pilot project will allow Haleakala Ranch to learn the R-1

application system and make any adjustments necessary before

applying R-1 water at a landscape wide scale.

R-1 Opportunities

• R-1 can be used to reestablish groundcover plants that have been overgrazed by axis deer.
• This water would also recharge surficial aquifers and assist with wetland health by raising the elevation of ground water.
• By regrowing forage for livestock, R-1 water will help with local food security.

Riparian Protection�Kulanihakoi and Waipuilani Riparian Rehabilitation

• These projects would be developed in a similar fashion to the Keokea Riparian Rehabilitation. Each site would begin with approximately 2,000 native dryland forest plants, axis deer fencing, and irrigation infrastructure.
• These projects would provide learning experiences for students from the new Kihei high school.
• In addition to providing native dryland forest habitat, these projects will filter stormwater sheet flow during storm events and improve water quality.

Detention Basins Mauka of Piʻilani Highway

• Kaonoulu Ranch, Maui County Department of Public Works, Haleakala Ranch, Central Maui Soil and Water Conservation District, the National Fish and Wildlife Foundation, and Malama Haleakala Foundation are working with the U.S. Natural Resource Conservation Service to establish a Kulanihakoi detention basin mauka of the urban corridor.

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• This basin could potentially capture millions of gallons of sediment laden stormwater.

Fire Management �and Mitigation

• NRCS, HDOH, The Central Maui Soil and Water Conservation District, Haleakala Ranch, Kaonoulu Ranch, and Mahi Pono are all working together to address the recent fire damage associated with the Pulehu Fire.

Firebreaks and Additional Axis Deer Fencing

Community �Wildfire Defense

Haleakala, Kaonoulu, and Ulupalakua Ranches have requested financial assistance for

fire breaks to be placed at the interface of wildlands and residential communities to protect

people and property from wild damage.

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• Approximately 19 miles of fire breaks
• Nine additional cisterns to be used as dip tanks for helicopters and as water caches for fire fighters
• Fire fighting equipment for first responders

Thank you for your time!