Sometime around 2 a.m. on Jan. 31, Mike Conners received a text from a frantic friend in a nearby unit of the Kīhei Kai Oceanfront Condominiums that she’d just heard a big crack as rain and floodwaters raged around them.

Within 20 minutes, a portion of the 16-unit building sank about 5 feet, trapping one couple. They were forced to cut out a screen window and climb to safety with the help of a condo employee, said Conners, president of the owners’ association.

No one was hurt, but the residents of Kīhei Kai were left with a badly damaged building and a costly cleanup.

Flooding is an annual problem in low-lying South Maui, caused by rainwater rushing down the mountainside. It has long wreaked havoc on homes, businesses and roads, and many say it is getting worse.

Maui County says while it is following a master drainage plan, South Maui’s wetland origins make it inherently vulnerable to flooding. But residents and environmental scientists say more concrete action needs to be taken, and more quickly. 

“The amount of damage that we saw last year and this year is really hitting home to people the power of this water,” said Robin Knox, lead scientist of the Save the Wetlands Hui. “And things that we have done with our land management and built environment have caused the situation to be worse.” 

The strong winter storm that passed through the islands on the night of Jan. 30 brought heavy showers to Maui County, where the 10.17 inches of rain that fell in the Upcountry town of Kula over a 24-hour period were the most of any other location in the state. It knocked out power for thousands of people, closed beach parks, broke water lines in Kīhei and Kula, and forced the closure of South Kīhei Road as crews cleared mud and debris that made it impassable in places. 

Residents have come to expect this every winter. In January 2024, South Kīhei Road was closed for emergency repairs after flooding undermined and destroyed part of the roadway. In January 2023, muddy floodwaters inundated Kīhei and a young firefighter died after getting swept into a storm drain. In December 2021, a powerful Kona low wrought so much damage that both the state and county issued emergency declarations.

South Maui’s terrain and urban sprawl are part of what makes it so susceptible to flooding. From the summit of Haleakalā to the coastal areas of South Maui, there are three watersheds encompassing nearly 50,000 acres, with 11 major drainage basins discharging to the Kīhei-Wailea-Mākena coastline, according to the 2019 Southwest Maui Watershed Management Plan prepared by Maui Environmental Consulting for the state Department of Health. 

The three watersheds include some of the nation’s fastest growing population areas, increasing an average of 3.3% per year Upcountry and 10% per year in the coastal areas at the time of the study. This has led to more development and hard surfaces that don’t allow water to soak into the ground, as well as the loss of the natural environment, the plan says.

Historically, South Maui’s freshwater and brackish wetlands would have slowed and filtered the floodwaters, allowing it to recharge the aquifer and protect coastal reefs from sediment. But now, floodwaters barreling downslope have fewer places to spread out and absorb back into the earth, said Knox, who was also involved in watershed plans for the area more than a decade ago.

“The erosion of a mountain and carrying of sediment to the sea, that’s a natural process,” Knox said. “But all of the deforestation and the invasive species and building impervious surfaces and all of those things have contributed to making it a more dangerous situation.”

That’s why Knox thinks restoring vegetation on the mountainside is one of the most critical solutions. Vegetation isn’t just needed upslope but also along the banks of rivers and gulches to help slow and absorb water, she said. Pouring a concrete culvert in a gulch may seem like a better short-term solution, but restoring the natural environment is the ultimate goal, Knox said.

While Knox is more supportive of natural solutions, she says it’s going to take a combination of conventional and ecological fixes to mitigate flooding, including detention basins to capture overflow from streams and direct it back when flooding subsides.

David Whitney, a professional engineer and CEO of EcoSolutions, which has offices on Maui and Hawai‘i island, also supports ecological restoration on the mauka side of Pi‘ilani Highway as well as ensuring the county has “properly sized drainage channels, culverts and bridges that donʻt clog or impede flow.”

Whitney, whose firm proposed environmentally friendly alternatives to the county’s drainage plan while it was in development, said that the key is in dispersing stormwater rather than concentrating it. 

“There needs to be more and greater opportunity for stormwater collection, storage and infiltration,” Whitney said via email. “It is the regeneration of the hydrologic cycle. We need to revisit the past and understand the ahupuaʻa system and embrace the idea of living mauka to makai. Currently there is a gap between mauka and makai. Once this is reconnected, as it was previously, it is my opinion that we will be (on) a better path moving forward.”

The watershed plan outlines goals that include promoting aquifer recharge by capturing stormwater in detention basins and improving natural buffers along gulches to help slow sediment. It also calls for better management of rural and agricultural lands by controlling wild animals and planting vegetation, as well as management of urban areas by protecting existing wetlands and promoting programs that would keep stormwater runoff on development sites instead of directing them toward drains that lead to coastal waters.

Maui County’s Kīhei Drainage Master Plan, released in 2022, also has plenty of recommendations. Acknowledging that “the existing storm drainage system on South Kīhei Road is not meant to convey large runoff,” the plan outlines specific needs for detention basins, diversion channels, culvert replacements and other improvements in each district of South Maui. The changes are proposed over three phases, with the first phase expected to take 5 to 10 years and the third phase anticipated for 20 or more years.

It won’t be cheap — upgrades in the Kūlanihāko’i District, including a new bridge on South Kīhei Road, are estimated at $82.2 million, by far the costliest of all the districts. The gulch has received some of the most attention in recent years, with sediment removal efforts in 2023 and 2024 following major storms. In December 2023, the Mālama Haleakalā Foundation landed a $354,000 private grant to design a stormwater detention basin in the Kūlanihākoʻi area.

The county departments of Public Works and Planning did not respond to a request for comment last week about the work the county has done to mitigate flooding in South Maui. 

But Mayor Richard Bissen said the county is following the guidance of the drainage plan by “conducting ongoing engineering studies and implementing mitigation efforts, including exploring potential drainage basins mauka side, sediment removal at Kūlanihāko‘i and Waiakoa Gulches, and other strategies to reduce flood risks.”

“However, due to South Maui’s wetland origins, the area will always remain vulnerable to flooding,” Bissen said in a statement to the Hawai’i Journalism Initiative.

But after so much destructive flooding, some feel like the county hasn’t followed through.

“They can’t tell you they don’t know what to do because they’ve been told what to do with multiple studies,” Conners said.

He is used to the flooding but says the property damage was worse this year. Nearby condos hardened their entrances with floodgates, sending the stormwaters into the Kīhei Kai Oceanfront Condominiums, an aging wooden 24-unit complex on the beachfront. 

The floodwaters undermined the foundation of one of the buildings and took out the beachfront and about 60 feet of sidewalk fronting the condos. Four people lived in the condos that fell. Others in the small complex offered couches and lanai space to the displaced. 

All of the residents are part time, including Conners, a Minnesotan who spends winters here in the condo his family has owned since 1984. This year, they’ve already spent thousands of dollars removing debris from the property, none of which is covered by insurance, and will likely have to go through a months-long process of getting the damaged facilities reviewed by an engineer. Conners said they’re already reaching out to attorneys and contractors in preparation to repair the building. 

Conners is worried about the bridge just before the Kīhei Canoe Club where debris and mud pile up and push floodwaters onto the road. 

“There has to be solutions to … storing and slowing down the flow of that water down the mountain,” he said.

Just down the road from that same bridge, the cluster of businesses that include Sugar Beach Bake Shop and Ululani’s Hawaiian Shave Ice was forced to close for six days while employees worked to clean out thick layers of mud in the buildings and parking lot.

CEO David Yamashiro, who co-founded the businesses with his wife Ululani and business partner Brad Edgerton, said the loss in revenue — an estimated $8,000 to $11,000 per day for the bakery, shave ice place and merchandise shop combined — was a hard blow, especially after losing two Ululani’s locations in the August 2023 wildfires and closing another Kā‘anapali location shortly before the blaze. The three West Maui shops used to bring in more than $2 million a year. 

Yamashiro lives in Kula and knew it would be bad for his businesses when the rain started to pour on the night of Jan. 30. Kīhei also logged over 4 inches of rain.

“Here we go again,” he thought.

Yamashiro said his South Maui businesses have been in the same location for 13 years but only started to get walloped by flooding within the last four years — once so badly that they were forced to close for nearly three weeks. He thinks part of that has to do with bridges in the area getting clogged with debris and the removal of vegetation on property mauka of his shops.

But, he says both the county and local businesses have gotten quicker at the post-storm cleanup. 

“Everybody has been more efficient, but being efficient after the fact, it really doesn’t help,” he said. “The optimum situation would be for it to be eliminated from happening, and I don’t know whether full elimination is possible, but at least minimizing the impact.”

Maui County Council Member Tom Cook said he plans to continue working with the administration and advocating for more funding for flood mitigation upslope. A few weeks ago, he visited ranch lands above Maui Meadows and said it’s clear just how much impact the recent periods of drought and the rampant herds of axis deer have had on the mountainside vegetation.

Cook, who’s lived in Kīhei for 16 years and holds the South Maui seat on the council, pointed to the $1 million included in the county’s budget for a flood study in North Kīhei that could attract state or federal funding to help with flood control.

He agrees that the solution “isn’t like just concrete channels — it’s managing the floodwaters so that it is beneficial and not destructive.” He believes in the need for more detention basins and diverting floodwaters to pasturelands, but says the problem isn’t going to get better right away.

“Best case scenario to me, this can be addressed in such a manner that the water and the soil is utilized … and that when it floods, it’s seldom or less often and less detrimental,” Cook said. “It’s unrealistic to expect that you’re going to be able to stop all the water getting to Kīhei.”