I don’t understand why Congress doesn’t reign in these rogue agencies.
You've got two dots.
Connect them.
The simplest explanation is that it is because the Congress agrees with these agencies and their regulations.
A great example is when the NSA was revealed to be engaging in domestic espionage on us, the citizens, the congress basically wrung their hands saying how awful
or justifying it (because we gotta catch those terrorists
) but not actually doing anything about it. (The IRS, EPA, BATFE, DOJ, etc are all the same.) — In short, it allows them to avoid accountability by whining and crying that it's the executive branch.
Because they can't.
Congress, between 1955 and 1972, passed a raft of "environmental" laws which basically stated goals like "we will have clean air", and "we will not pollute water", and delegated to the Executive Branch the power to issue regulations with the force of law to accomplish those goals.
Now, I think that delegating exclusive powers granted BY the People of the United States TO Congress is unconstitutional. The US Supreme Court agreed until 1937, but since the famous "switch in time that saved nine" the Court has allowed such delegation of lawmaking power to the Executive Branch.
The problem is not the EPA (well, the MAIN problem, anyway). The problem is the unconstitutional laws. Congress did not create the EPA, it was created by Executive order. Since it has no statutory authority to operate, there is no underlying legislative framework to repeal. And if a President revoked the Executive order creating the EPA, thousands of revolutionaries in the Departments of the Interior, Agriculture, Commerce, Labor, Energy, Transportation, and now Homeland Security would go right on issuing regulations to enforce the laws that empower the Executive Branch to pursue the utopian goals of Congress's own foolish environmental legislation.
Two things are necessary to "rein in" these "rogue agencies".
The first is repeal of the Clean Air Act (1963), the Wilderness Act (1964), the Water Quality Act (1965), the Wild and Scenic Rivers Act (1968) and the National Environmental Policy Act (1969). All these laws allow, and arguably command, the EPA to do what it is doing.
The second is an Amendment to the Constitution to state the obvious, which everyone knew from 1788-1937, that the phrase "All legislative powers herein granted" that begins Article I means that those powers which belonged to the People of the United States and to the several States prior to the grant of such powers to Congress ARE NOT SUBJECT TO DELEGATION.
The EPA and the other "rogue agencies" are a convenient target for Members of Congress to use in order to justify their inaction to their constituents, but the agencies are not the problem. The problem is the laws, and only Congress can fix that.