I think you're spot on. Damn failures are on the rise, and usually it's due to the simple fact that maintenance is expensive and everything has a shelf life. A lot of these dams were built during the same time period and the cost to replace / maintain the aging infrastructure is tough for small communities to swallow. And they're all coming due at roughly the same time.

Selling to a larger company who hopefully has the capital to fix them seems like a bargain when compared to the cost of replacing a hydro dam (or even replacing it with a non-electric generating dam).

Of course, that does come at a cost, and it's probably spread across all rate payers.