The city will pay a $100,000 fine and make a series of improvements as a result of the August 2015 discharge of storm water and raw sewage at Ala Moana and other south shore areas and two city facilities, under an agreement reached with the state Department of Health that was announced today.

It was not immediately clear how much the city will need to spend to make the improvements.

An consent order signed by the city and Health Department cites three unauthorized discharges of pollutants that contaminated and shut down state waters from Waikiki beach to Kakaako following a major storm. City officials at the time blamed the inability of a pump station to process the sewage and storm water. Only one of two pumps at the Keawe Street Wastewater Pumping Station was operating during the deluge because the other was undergoing refurbishment, city officials said.

Much of the backflow spilled out of manholes at Atkinson Drive and Ala Moana Boulevard, and then entered storm drains leading into the ocean, city officials said. One witness reported a small geyser shooting out of Ala Moana Boulevard near Fisherman’s Wharf resulting in “a sea of gray water” spilled that smelled like a toilet and left behind undissolved hygiene items.

According to the order, an estimated 462,050 gallons were spilled into the Ala Moana-Kakaako area, 125,000 gallons at the Kailua Regional Wastewater Treatment Plant and 4,950 gallons at the Kaneohe Treatment Facility. Oahu rainfall totaled more than 3 inches during a 24-hour period, setting a record for that date.

City officials insisted that Waikiki beaches were closed “out of an abundance of caution” the day of the spill as the result of a brown water advisory issued by the Health Department. Ala Moana was closed off for several days due to contaminants found in water samples.

Under the voluntary agreement, the city is required to revise its sewage spill volume estimate procedures, revise its standard procedures to improve response time to spill prevention alarms, upgrade its sewage system supervisory control and date acquisition system, and develop a high-density urban area storm-water inflow detection, identification and quantification study. An estimate on how much that will cost was not immediately available from city officials.

The $100,000 penalty is to be paid to the state within 90 days.