University of Hawaii scientists have begun a yearlong study to see whether pumping treated sewage into injection wells is causing pollutants to seep into coastal waters in the West Maui resort area.

"We have heard anecdotal stories that there’s something going on along the coastline, but without data we can’t tell what’s really happening," said Dean Higuchi, spokesman for the Environmental Protection Agency in Hawaii.

The EPA defines an injection well as vertical pipe "that places fluid deep underground into porous rock formations … or into or below the shallow soil layer."

Higuchi said the study "was primarily prompted because of the county’s need to renew its Underground Injection Control permit" and is not related to an environmental group’s stated intention to sue Maui County over effects of the wastewater injection wells on near-shore waters.

The Lahaina Wastewater Reclamation Facility, between Kaanapali and Kapalua, handles 4 million to 6 million gallons of sewage per day. The plant performs secondary treatment, and 1 million gallons per day is further disinfected with ultraviolet light and used for irrigation.

The rest of the treated sewage is disposed of in four injection wells, about 2,000 feet from the shoreline.

Last week, scientists from the University of Hawaii Department of Geology and Geophysics added bright green tracer dye into two of the injection wells. Researchers will measure how long it takes for wastewater to flow to the near-shore ocean water, the EPA said in a news release.

UH and state Department of Health staff will take periodic ocean water samples at identified ground-water discharge points to assess water quality, the release said.

"The tracer study will help us pinpoint wastewater movement from the Lahaina injection wells," Alexis Strauss, director of the Water Division for the EPA’s Pacific Southwest Region, said in the release. "The goal is to evaluate the potential impact of the facility’s discharge on the coastal waters."

Results of the test and monitoring will be made public later this year.

Earthjustice sent Maui County formal notice on June 29 that it intends to sue the county for alleged violations of the Clean Water Act. It plans to file a suit at the end of August, Earthjustice attorney Paul Achitoff said.

"Different chemicals go into the ocean as a result of the wells. The nitrates and nitrogen compounds from the treated wastewater cause the accumulation of algae and algae blooms, leading to the degradation of the coral reef offshore," Achitoff said.

Maui County spokesman Rod Antone said the facility is in compliance with all permit conditions and applicable laws.

The study will cost an estimated $250,000 and is funded by the Army Corps of Engineers, the EPA and the state Department of Health. Maui County will pay $45,000 to $60,000 for laboratory testing of water samples, county officials said.