When that is applied to an indian(s) treaty right to fish it is difficult to apply because it is not a specific amount of water, so it really becomes a minimum flow, or sets a minimum flow in the river.
Likwise, the flora and fauna on federal land or the flora and fauna that depend on federal water(water created by the feds impounding water) has a water right that is impossible to allocate for so it is also a minimum flow.
So during times of drought, a prior appropriation water right holder(possibly a farmer) would not get his water because if he did get his water, it would reduce the water in the stream to below the minimum flow.
A specific example is the delta smelt. Because of the drought, some farmers with junior water rights were denied water because of the minimum flow.
Same way with the conflicts a number of years ago on the Klamath River. In that case the Indians had a treaty right to fish. The federal wildlife refuge had a water right. And the suckers in the lake had a water right. OTOH, those farmers with junior prior appropriation rights were denied water. But those farmers with riparian rights kept their water.
So Bush cut off the water and there was a big die off of Salmon in the river.
If you convert the federal land to state land, then the minimum flow for the federal land doesn't apply.
The way the issue always play out is that one group says there doesn't need to be a minimum flow, that any drop of water not utilized is wasted. The other group says there has to be a minimum flow, but within this group there will be wide dis-agreement as to what the minimum flow should be. The second group sits at the table and negotiates a deal, but the first group that said no to a minimum flow doesn't get a seat at the negotiating table.
In the case of the Klamath river, they sat down and negotiated a deal on the entire watershed, which is now being implemented.
Thanks. I find the whole thing more than a little confusing.