Texas' 16 Regional Water Planning Groups don't really have any thing to do with who owns the rights. This all came out of the '99 Texas Water Development Plan which decentralized power of planning and has created a lot of unintended consequences.
Where as the article above deals with Prior Appropriation Rights, Texas straddles the wet-dry line so it uses a dual doctrine of both Riparian Rights and Prior Approriation Rights.
Just an associated train of thought. I didn't think anyone would make or take my response as an association between my random thoughts and this article's topic.
Sorry about that. I do things like that sometimes.