Eastham Bridge collapse 'caused by fast-flowing water'
The collapse of a Grade II-listed bridge was caused by "fast-flowing water", an investigation found.
Eastham Bridge, in Tenbury Wells, collapsed in front of a horrified school bus driver in May.
Worcestershire County Council has now discovered one of its pier foundations was the victim of "scour" - the erosion of sediment around the structure.
No concerns were reported when the 18th Century bridge was last inspected in December 2015.
Bridges in the county are inspected every year for signs of bridge scour, such as holes developing around the base or foundations at piers and abutments, where the condition is most common.
The council estimates it will take two years to rebuild the bridge.
The collapse - which happened shortly before the school bus attempted to cross - had been blamed on drivers ignoring weight restrictions.
However, Marcus Hart, cabinet member for highways at Worcestershire County Council, said: "We believe that it was scouring that led to the bridge collapsing."
Mr Hart confirmed a full report by independent experts would be released "as soon as we receive it".
He also said the council was investigating if building a new permanent crossing to replace the bridge would be cheaper and quicker than a temporary replacement.
The replacement has been delayed by the need for an environmental impact assessment into how it would affect the surrounding area, a Site of Special Scientific Interest.