Legal Question in Real Estate Law in Illinois

I see you added some information to this situation, but I must tell you that it remains insufficient in several respects and I recommend you and the other 2 owners who are being asked to contribute see an attorney with this situation. You assume the owner who cut through the dam is "90%" and "primary" owner, but that is equivocal. With that being said, once you get through the ownership and control issues, the issue is whether what the owner who cut through the dam did was reasonable, or unreasonable. Consequences of actions (draining the lake and consequent loss of property value -- and potentially other issues) do not necessarily on their own mean that the action taken was unreasonable. For example, if the dam was in sore need of repairs and a break could have flooded his and everyone else's property, and repairing the dam in place was cost ineffective and the only way to relieve the situation was to cut through the dam and allow it to drain naturally until repaired (and hopefully refilled), and nobody else was stepping up, then what this 1 owner did may in fact have been reasonable and there may be NO liability and all the owners may have to share in the repair costs.....