The Central Maui Soil and Water Conservation District said that the Pohakea Watershed Plan was recently approved by the state Department of Health’s Clean Water Branch, which means that the projects within the watershed are eligible for funding.

“Land management plays an important role in maintaining healthy coastal waters,” the report says. “Coral reefs are important culturally, economically, and ecologically.”

Watershed planning efforts are coordinated by the Clean Water Branch’s Polluted Runoff Control Program, which has a mission to “protect and improve the quality of Hawaii’s water resources by preventing and reducing nonpoint source (NPS) pollution,” according to a news release.

“We are proud to support this project that enhances comprehensive stewardship of the Pohakea Watershed and facilitates the ability to utilize EPA funding to mitigate impacts to coastal waters,” said Program Manager Justine Nihipali. “The Pohakea Watershed Plan was developed to address land-based sources of pollution entering into Maalaea Bay.”

Many stream banks within Pohakea Watershed experience erosion, one of the many problem areas that the recently approved management plan aims to address. — Photo courtesy Central Maui Soil and Water Conservation District

Encompassing about 5,268 acres, the Pohakea Watershed extends from the summit of Hanaula at 4,616 feet of elevation in Mauna Kahalawai to the southeast where its gulches and gullies drain into the waters of Maalaea Bay.

In 2018, the nonprofit Maui Nui Marine Resource Council requested that Maui Environmental Consulting LLC conduct a study to investigate and address land-based sources of pollution within Maalaea Bay and Maalaea Harbor.

The study focused on erosion and sediment carried down by storm waters, according to the watershed plan. It also identified nutrient, pathogen or other pollutant sources, as well as any other land management practices that may be contributing to water quality degradation in the watershed.

The results of this study were compiled into the Pohakea Stormwater Management Plan. Several projects proposed in that plan have already been implemented, the report said.

The stormwater plan was then updated and expanded into a full-scale watershed management plan.

Considering the environment, economy and community, the Pohakea Watershed Plan aims to protect and restore water quality, especially in the face of runoff that often clouds the coastline when it rains or floods, the Soil and Water Conservation District said.

According to DOH and Integrated Water Quality Reports, the coastal waters within Pohakea watershed are listed as impaired for several parameters, including ammonium, turbidity, chlorophyll-a, enterococcus, total nitrogen, and nitrates and nitrites.

The Soil and Water Conservation District said in the news release that the goal of the Pohakea Watershed Plan is to further identify the various sources of pollution within the watershed, and to provide the best management practices and strategies “that will empower watershed coordinators, stakeholders, resource managers, policy makers, and community members to combat water pollution.”

The plan divides the watershed by land use types and develops possible management strategies for each area. Most of the land in the watershed is already designated as conservation land, but some are agriculture and urban.

It was also determined that management of sediment within the land recently acquired by Hope Builders LLC and West Maui Construction Inc. “would be most beneficial” to reducing sediment entering Maalaea Harbor and Maalaea Bay. The two companies bought 257 acres in Maalaea last year.

Some of the strategies for the watershed include excavating basins to capture stormwater, adding ungulate fencing, planting vetiver grass, rehabilitating streams, upgrading injection wells for Maalaea condominiums and businesses and stabilizing head cuts to decrease the slope and reduce streamflow. The basins, head cut stabilization and injection well upgrades are listed as high priorities in the plan.

The costs and timeline will vary depending on what strategy is used. Costs range from under $1,000 to over $1 million per project, with some taking anywhere from six months to 10 years to complete. Some project costs could be lowered with the help of grants and volunteer work.

This plan, which is eligible for Section 319 EPA funding, was made possible with support from the state Office of Planning and Sustainable Development, Coastal Zone Management Program.

Work and project timelines will follow the grant cycle. Proposals are typically issued on an annual basis in July or August.

The final plan can be found at: health.hawaii.gov/cwb/clean-water-branch-home-page/polluted-runoff-controlprogram/watershed-plans/.

* Dakota Grossman can be reached at dgrossman@mauinews.com.