How is sea level rise going to affect wastewater systems in Kailua-Kona? A UH Hilo graduate student investigates
Ihilani Kamau is tying together current water quality conditions along with sea level rise predictions in order for government agencies and communities to make appropriate plans for the future.

By Susan Enright and Nāpua Iolana Bicoy.
A graduate student at the University of Hawaiʻi at Hilo is wrapping up a study looking at how sea level rise will impact sewer infrastructure, cesspools, and future water quality in Kailua-Kona on Hawaiʻi Island.
Ihilani Kamau, born and raised in Hilo, Hawaiʻi, is in the tropical conservation biology and environmental science graduate program. She will be graduating in the fall.
“The purpose of this project is to assess potential water quality impacts based on current water quality conditions in order to predict how it will be impacted in the future during sea level rise,” Kamau says. Sea level rise is an increase in the level of the world’s oceans due to the effects of global warming.
“Another purpose is to document and identify sewage pollution hotspots along the Kailua-Kona shoreline and determine which onsite sewage disposal systems and wastewater treatment infrastructures will be affected by sea level rise.”
Research methods and preliminary findings
Kamau is collecting data along the coastline from Kailua-Kona to Keauhou.
“We have 12 different stations along the shoreline and the samples are collected monthly for a whole year,” explains Kamau.
The research involves a multi-indicator approach in order to detect the presence of sewage pollution. This approach uses indicators such as frequency of bacteria, pathogens, nutrient concentrations, isotopes, and also a macro algae nitrate analysis. “We use all these different parameters in order to more accurately detect the presence of sewage pollution and better understand the current conditions of the shoreline,” says Kamau.

In a statement about the preliminary findings from Kamau’s research, Steve Colbert, associate professor of marine science who is chair of the department and an advisor on this study, says the testing has revealed that “Enterococcus spp., a fecal indicator bacteria used by state and federal agencies to evaluate health risks associated with swimming in waters contaminated with sewage, were above the two standards used by the state at several stations. Staphylococcus aureus, a bacteria that causes skin infections, was also present at some of the same stations. But it’s antibiotic strain, MRSA, was not detected.”
For the sea level rise portion of Kamau’s project, she uses pressure loggers in order to document the rise and falls of the water levels. With this data, she creates a sea level rise model.
“The sea level rise model tied with the current water quality conditions will be used to help determine which onsite sewage disposal systems and wastewater treatment plants should be removed, relocated, or converted in order to adapt to future sea level rise,” says Kamau. “So my whole project is tying together current water quality conditions along with sea level rise predictions in order to make appropriate plans for the future.

Kamau says that during her investigations, she discovered that a lot of people did not know that sewage pollution is an issue on the Kona side.
“This whole project actually stemmed from community members reaching out to us saying that they’re seeing this issue and they want more research to be done about it,” says Kamau. “But when I was actually out in the field collecting data, not a lot of people within the community who [frequently visit] these beaches actually really knew much about sewage pollution being a problem there.”
“It’ll be really good that after this project,” she adds, “I’ll be going back to the community and sharing what I’ve found in those areas, to let them know I’m keeping up to date with all of that.”
Support through collaborative partnerships
The project is funded by the UH Pacific Islands Climate Adaptation Science Center, a partnership of federal and academic institutions that provides scientific information and tools to help natural and cultural resource managers and communities cope with the impacts of climate change.
The primary partners Kamau is working with are the County of Hawaiʻi; The Kohala Center, which is a community-based nonprofit located in North Kohala that conducts research, education, and stewardship for healthier ecosystems in Hawaiʻi; and the nonprofit Waiwai Ola Waterkeepers and their Kona Coast Waterkeeper group.


Professor of Marine Science Tracy Wiegner, who is Kamau’s advisor, says, “It really did take a village to get the project started and collect the data.”
Assisting in the project were two alumni from the tropical conservation biology and environmental science graduate program, Crispin Nakoa, now a doctoral student at Arizona State University, and Walter Boger, who now works with Lynker, an environmental consulting organization; undergraduate marine science students Katie Cartee, Morgan Youngblood, and Sierra Hall; a summer intern from UH Hilo’s Pacific Internship Programs for Exploring Science, Amber Skiwo; and Kamehameha High School student Silas Piʻianaia who assisted Kamau in the field and lab.
“It was also a family affair,” says Wiegner. “Ihi’s sister was a trusty field assistant, and her father often went along as well.”
For sea level rise measurements, Wiegner and Kamau collaborated with students of Professor of Geography Ryan Perroy, Olivia Jarvis and Kainoa Lindiwe, UH Hilo affiliate faculty and marine ecologist Lisa Marrack, Liliʻuokalani Trust, and Kamehameha Schools.
“We’ve also spoken with the Hawaiʻi Department of Health and NOAA for additional information on insights on how we can improve our sea level rise models and predictions of future water quality,” says Wiegner.
Currently in the works is planning for a coordinated project with The Kohala Center, which manages the Kahaluʻu Beach Park Education Center, to conduct dye tracer tests with local homeowners to document the connection between cesspools and coastal springs in the area.
Kamau also is interfacing with the state Department of Land and Natural Resources’ Division of Aquatic Resources. “I’m working with them by sharing information and data that I’m collecting within my project,” says Kamau. “And meeting with them to see if they have any feedback to give me to improve my project or change anything.”
Impact on communities and the environment
Kamau says her research on Kailua-Kona water quality and the predicted sea level rise will have a big impact on Hawaiʻi Island communities and well as the environment.
“We all know that sea level rise is an important topic and issue to discuss and this project will help create a better adaptation plan in order to address sea level rise,” she explains. “So the results from the project will help people know which cesspools could be inundated due to sea level rise, which can help the county make better decisions in planning to remove, relocate or convert these systems in order to prepare for the future.”
She also notes that by taking actions early, “we’ll be able to decrease the amounts of sewage effluent would possibly be released into the near shore waters in the future. And this will help ensure the health and safety of our community members as well as ecosystems.”

Hoping to make a difference
Kamau hopes to stay in Hilo or the state after graduation. She wants to be able to contribute to her own and other communities in Hawaiʻi.
“I just want to be able to make a difference,” she says, “whether it be out in the field collecting data or in a classroom teaching students or even in an office, being part of a planning process, I would be happy, in order to better my community and my people. I just hope to be making a difference by using all of the manaʻo and skills that I have gained through my education and everything that I’ve seen.”
Story by Susan Enright, a public information specialist for the Office of the Chancellor and editor of UH Hilo Stories. Nāpua Iolana Bicoy, a Hawaiian studies major at UH Hilo, contributed.