Climate Change, Culture Crash?

Seven times since the year 2004 the Monocacy Creek at Bethlehem has surged over its banks. Each time it has inflicted serious damage on historic industrial buildings administered by Historic Bethlehem Partnership, and on a surrounding area that has long been the site of large-scale outdoor events.
The buildings flooded include the 18th century Moravian Tannery and Waterworks and the 1869 Luckenbach Mill, which houses HBP offices. The Waterworks building suffered particularly heavy damage in the recent (July, 2010) flooding. The structure is a National Historic Landmark and a Historic Civil Engineering Landmark--- it is believed to be the oldest municipal waterworks in the United States. It was fitted with a new wheel just last year, at a cost of around $150,000. But the wheel has been jammed by flood water, and it is impossible to determine whether it still works.
The outdoor events which have been impacted by Monocacy Creek flooding have included two popular tourist attractions, the giant Musikfest and the popular annual Celticfest.
I've seen an estimate that 50,000 people visit the Monocacy Valley's attractions every year. That sounds low to me, and perhaps it only counts people visiting Historic Bethlehem's sites. But it still is a large number of people. The loss of a crowd that size could make quite a hole in Bethlehem's tourism revenue.
What is causing this era of recurrent floods in the Monocacy Valley? Climate change is one possible answer. But a knowledgeable former city official is also convinced that something else is in play. It might be called the doctrine of impervious surfaces--the idea that urban flooding can be intensified, as it was recently in Nashville, TN, by the rain falling on roofs, sidewalks, and parking lots instead of onto grass and soil. This results in the water not being absorbed and pouring into streams and rivers. Serious floods ensue.
Meteorologists are beginning to take this view of things; and it certainly might apply in Bethlehem. The once-bucolic townships north of the city, through which the Monocacy flows, are now teeming with homes, schools, and malls. Yes; and of course parking lots.
Whether the problem here is climate change or impervious surfaces or both, with some other things thrown in, it will not be easy to solve. It has even been suggested that the Army Corps of Engineers be called in, an idea that I am sure gives many people a feeling of dread. The Corps has been blamed for a number of misjudgements during its history, including making the disaster of Hurricane Katrina worse than it need have been.
All that is clear is that failure to solve the flooding problem along the Monocacy could have the not-so-long-term effect of seriously damagaing Bethlehem's quality of life. And that would be very sad.