"This naked land grab hides behind claims of preserving clean drinking water, wildlife habitat, and endangered species."
Article VI, Section 2,
the laws of the United States which shall be made in pursuance thereof; and all treaties made, or which shall be made, under the authority of the United States shall be the supreme law of the land; and the judges in every state shall be bound thereby, any thing in the constitution or laws of any state to the contrary notwithstanding.
If you check, which I have, you will find that all the laws dealing with clean water and wildlife are based on treaties.
So, our federal government does have constitutionally granted legislative jurisdiction.
"In Congress, theres also a Highlands Conservation Act (H.R. 1964 & S.999) that would give more than a $100 million to the governors of Connecticut, Pennsylvania, New York and New Jersey"
Amendment V,
...nor shall private property be taken for public use without just compensation.
It appears that Congress is performing it's constitutional duty making sure there is "just compensation" available to private property owners whose property will be taken by the NHA.
So, from a constitutional perspective, there is no violation of the action by our federal government to call in question.
The only thing that can be done to stop the constitutional land grab is for the rest of the U.S. citizens to lobby their Congressmen to rescind the appropriation that is required to satisfy the Fifth Amendment property rights protection.
The powers those treaties require for enforcement exceed the Constitutional powers of the Federal government. The administrative "rules and regulations" thereunder are written, enacted, enforced, and adjudicated by the executive branch in clear violation of the separation of powers principle. Those regulations devalue that land and socialize the associated resources. The feds will end up paying a vastly discounted price simply by virtue of the threat of the conservancy.
You call that Constitutional. You are either clueless or a spin artist, take your pick.