"We don't want to leave the government off the hook...when they have the obligation to do that," Moonias said.

"The government is responsible to provide that service."

Where is it written that government is obligated to provide water treatment plants and their maintenance? If so what else?

I thought federal government is obligated for financial support, the rest should remain the responsibility of the communities as to how they manage, or mismanage, that support.If they have contaminated water it is their responsibility. The only time government should get involved is if some other entity, not the community itself, is responsible for the contamination.
The natives are not fauna and flora which has to be managed but are rational and responsible beings.

Am no expert but read portions of century old treaties. Anyone have different reasoning, interpretation and opinion?

This may bite us shortly. Ed.