Park Service: Stains on St. Louis Arch no cause for alarm

ST. LOUIS -- Corrosion and stains on the surface of the Gateway Arch may be unsightly, but they're not a danger to the iconic monument.

The National Park Service on Monday released an engineering report indicating the stains may be caused by the welds that hold together the 630-foot monument to westward expansion that sits near the Mississippi River in St. Louis. The service said the stains pose no structural concerns.

The service said the Arch is in "excellent structural shape." It promises to clean the Arch, but gives no timeline for that work. A cost estimate for the cleaning has not been outlined.