The owners of Big Island Dairy illegally discharged roughly 600,000 gallons of sewage that contaminated coastal waters through Ka­ohaoha Gulch.

The company reported the discharge to the state Department of Health at 9:10 a.m. Monday, at first estimating that about 800,000 gallons of wastewater would be discharged throughout the day from a lagoon on the property to “maintain the structural integrity” and “prevent an uncontrolled discharge” into Alaialoa Gulch, which runs through Ookala town, the DOH said. Pumping activities stopped around 3:40 p.m.

The Health Department has posted warning signs urging the public to stay out of Kaohaoha Gulch below Mamalahoa Highway due to the stormwater contaminated with animal waste.

The state prohibits discharges that “impair water quality,” and the dairy is required to submit a written report explaining the cause of the spill, which is being investigated by the DOH Clean Water Branch.

Owners and operators who fail to comply with environmental regulations for wastewater systems can face legal action by the state, federal agencies or private citizens. Big Island Dairy did not return calls for comment Tuesday.

Big Island Dairy previously said it would cease operations next year due to financial and regulatory issues.

In 2017 the dairy was hit with a federal lawsuit alleging violations of the Clean Water Act and a $25,000 fine by the Health Department after multiple wastewater discharges. The dairy released nearly 2.3 million gallons of rain and waste­water in May, contaminating gulches in the rural community.