SAGINAW, Mich. -- Dow Chemical and the U.S. Environmental Protection Agency have agreed on a plan requiring the company to clean up dioxin contamination in a Saginaw neighborhood.

EPA said tests in April revealed unacceptably high levels of dioxin in an area by the Lower Tittabawassee River. Dow said the contamination probably resulted from activity at its upstream Midland plant dating back a century or more.

Earlier sampling and analysis had identified the site, an area approximately 1,000 feet long and 150 feet wide, as encompassing locations having uncharacteristically high levels of contamination immediately adjacent to residential structures.

Under the agreement, Dow will clean the interiors of 11 homes close to the river. Their yards will be excavated and back-filled with clean soil. Unpaved surfaces of Riverside Boulevard will be cleaned.

Work at the site is expected to begin late this month and continue through mid-October.