The Martin Luther King Jr. Memorial Library is one of four libraries where elevated levels of lead were found in drinking water. (Michel duCille/The Washington Post)

On the same day the D.C. Public Library announced it found excessive lead contamination in four libraries, city officials said they will lower the maximum acceptable level of lead in public drinking water, making the District’s standards far stricter than those required by the Environmental Protection Agency.

Six water fountains and one sink in the city’s public libraries were found to exceed the EPA’s maximum lead contamination level of 15 parts per billion, library officials announced Tuesday.

Elevated levels were found in water fountains at the flagship facility downtown, the Martin Luther King Jr. Memorial Library, as well as the Lamond-Riggs and Southwest neighborhood libraries, and at a sink at Georgetown Neighborhood Library.

While six of the affected water sources tested slightly above the federal guidelines, a water fountain near the women’s restroom on the third floor of the MLK Library had a lead content of 192 parts per billion —­ more than 12 times the federal limit.

After lead-contaminated water was discovered in water fountains in three elementary schools in April, the city tested 114 drinking water sources at 26 libraries.

Library officials received the test results June 14 and shut down the seven contaminated sources that day, spokesman George Williams said. Filters were installed on all seven sources, and three were returned to service after a new round of testing found them to be beneath the limit of 15 parts per billion.

But even with new filters, three water fountains at the MLK and Georgetown Neighborhood libraries do not meet the new standard announced by the city Wednesday. An additional 74 drinking fountains at libraries across the city were found to have lead levels greater than the new standard of 1 part per billion, documents show.

They will all be taken out of service and remediated, Williams said.

“If the filter doesn’t create a safe level of lead in the water, then an additional step will be taken,” said Williams, adding that officials are not sure of the cause of contamination. Remediation could include replacing piping or fountain parts, he said.

Library officials last tested the water fountains at the MLK Library five years ago, Williams said. He had no record that drinking fountains in any of the other libraries had been tested previously.

The test results were released the same day city officials announced the citywide revision of acceptable levels of lead in drinking water at public facilities. Instead of addressing water sources with lead content above 15 parts per billion, the city will repair any source testing above 1 part per billion.

The change comes on the heels of a report published last week by the American Academy of Pediatrics that recommends state and local governments address lead levels exceeding 1 part per billion.

According to the EPA, the only safe level of lead contamination in water is zero.

Unsafe levels of lead in children have been linked to learning disabilities, impaired hearing, damage to the nervous system and slowed growth. In adults, it can lead to increased blood pressure, decreased kidney function and reproductive problems.

The city plans to install filters at all public schools, libraries and recreation centers, regardless of test results, by the end of the year, officials said.

Installing the filters and implementing the new limit will cost nearly $2 million initially and then $1.5 million annually to regularly test and maintain water sources, Deputy City Administrator Kevin Donahue said.

“Lead exposure in children is preventable, and we will be working diligently to set policy at our facilities that goes far beyond EPA standards,” Donahue said in a statement.

But parents, pediatricians and groups formed during the District’s water crisis more than a decade ago criticized the city Wednesday for poor oversight and weak communication about recent findings of elevated lead levels.

At a joint hearing of the D.C. Council’s education and environment committees on Wednesday, parents said the city has an inadequate system of testing for lead — checking most sources once a year or less frequently. And it does an even worse job of communicating results, they said.

One noted that the District’s Department of General Services, the agency responsible for testing, does not post recent results on its website and reports them only in English.

Parents whose children attend the three schools where elevated lead levels were found this spring were the most outraged. Two witnesses called the situation a “public health emergency” and demanded better communication from the city when unhealthy levels are found.

At the end of the six-hour hearing, council member David Grosso (I-At Large), said he was encouraged by Mayor Muriel E. Bowser’s proposed new lead threshold. “Hopefully, the public will start to see that we are behind full eradication of lead in D.C. water,” he said.

Aaron C. Davis contributed to this report.