MILWAUKEE (CBS 58) -- The Wisconsin DNR confirmed reports of a heavy oil spill on the Milwaukee River downstream from Silver Spring.

A warden responded and the DNR confirmed the spill source was City of Milwaukee owned stormwater pipes draining a small area on the west side of the river.

Officials say an absorbent boom was installed at the outfall.

The City of Milwaukee tested upstream stormwater basins, and they only found product in one catch basin.

Officials also say the spill was due to illegal dumping of an oil/petroleum product.

The DNR says if you see something say something. Contact the WDNR's Spill Line at (1-800-TIP-WDNR) with any tips.