The U.S. Environmental Protection Agency has sent the Hawaii Department of Health a stern letter warning state officials to do a better job protecting the public’s health when it comes to posting signs at beaches known to have unsafe levels of fecal-waste bacteria in the water.

The EPA also wants the state to do more thorough investigations into the sources of enterococcus at certain sites, such as Waiopili Stream on the south shore of Kauai.

The Surfrider Foundation has fought for years to have the department at least post warning signs there and other places where the nonprofit has routinely found extremely high levels of enterococcus, a bacteria widely used as an indicator of fecal contamination.

The department has resisted posting warning signs near Waiopili Stream, which flows into a beach where people swim and children play, because they haven’t been able to identify direct sources of human sewage.

The state has blamed the fecal waste of feral pigs, sheep, rats, birds and even a dozen land tortoises in the area for polluting the stream. 

The EPA says it doesn’t matter if the water is polluted by people or animals, the department needs to post signs.

And it’s not just a matter of whether the state should do this or not. The EPA says because the department receives BEACH Act grant money from the feds, the state is required to have “measures for posting of signs at beaches or similar points of access, or functionally equivalent communication measures that are sufficient to give notice to the public that the coastal recreation waters are not meeting or are not expected to meet applicable water quality standards for pathogens and pathogen indicators.”

In addition to posting signs at Waiopili Stream, also known as Waiopili Ditch, the EPA “strongly advises Hawaii DOH to immediately implement public health protection measures such as limiting access and conducting information outreach to the general public.”

“These actions, among other preventative measures, would be beneficial to protecting the public health of Kauai residents and visitors,” Nancy Woo, the EPA’s Water Division Ecosystems Branch assistant director wrote in a letter Monday to Alec Wong of the state Clean Water Branch’s Environmental Management Division.

The Department of Health did not return a message seeking comment Wednesday.

Surfrider’s Kauai Chapter has been campaigning for the department to post warning signs at chronically polluted beaches after its Blue Water Task Force’s water-monitoring data revealed overwhelming evidence of severe contamination of several coastal streams on Kauai, the group said in a post on its website.

The task force strives to assist local government water quality monitoring programs by testing waters at popular recreation sites and helping to fill in any data gaps in local programs, in order to protect public health, the post says.

Surfrider’s test of Waiopili Stream on March 12 found 15,531 bacteria per 100 milliliters. That’s more than 100 times the safe limit of enterococcus. It’s been even higher, too. Last April, it was 24,196. The lowest level Surfrider has tested over the past two years was 1,421, in June.

Heavy rains and relatively isolated weather events can spike the numbers, so the EPA says the water source is generally safe if it doesn’t exceed 130 bacteria per 100 ml more than 10 percent of the time. That’s the same guideline that Hawaii cemented in its administrative rules.

State and nationally recognized safe limits of enterococcus are 35 bacteria per 100 milliliters of water, based on the geometric mean of five samples.

The state tested sites in the area from November 2014 to March 2015, and the range was 120 bacteria per 100 ml up to 1,847. But the department’s detection limits are capped at 2,005, which was exceeded six times, throwing off the geometric mean.

The EPA, like Surfrider, has questioned the department’s testing.

Woo said in her letter that the EPA is “concerned that many of the conclusions drawn from the Sanitary Survey are not appropriately supported or contradict existing data.”

The EPA has asked to continue discussing Waiopili Stream with the department and what measures it plans to take to post signs at beaches throughout the state. Woo said she’d be contacting Wong to set up a time to talk soon.

Read the EPA’s letter to the Department of Health below.