Cell towers are a really integral part of carrier's business - I'm not certain whether most are owned by providers or other companies, but either way the folks that put the tower up owe the customer (be it a phone user, a phone provider or some subcontactor of the provider) an explanation and pay the costs of bad configuration... I'd also assume that making sure these towers stay up is someone's fulltime job (likely multiple people) - while there won't be an employee constantly monitoring city water systems since it would take so little of a single person's time.
Not a direct loss, but plenty of opportunity for indirect loss. Disrupting emergency systems is the first that comes to mind. Covert hacking and surveillance could also be used for assassination plots.