BENTON HARBOR, Mich. (AP) — Higher-than-acceptable lead levels have been found in tap water in more Benton Harbor homes.

The Herald-Palladium reports Friday that 27 of 159 homes tested had lead levels at or above the federal action level of 15 parts per billion. Another 38 homes tested as having between 5 and 14 parts per billion — above the state’s voluntary action level.

City Manager Darwin Watson says contractors will be hired to investigate the source of the lead. Benton Harbor is in southwestern Michigan.

Michigan’s Environmental Quality department put Benton Harbor’s water system under a state advisory for lead in October after eight of 30 homes sampled during the summer were above the action level for lead.

Elevated levels of lead in drinking water can cause health problems and developmental delays in children.