There is a regulatory drought in California imposed by the U.S. Fish and Wildlife Service, harming farmers, workers, towns and businesses throughout the San Joaquin Valley and Southern California. The service's water restrictions, imposed because of the Delta smelt -- a finger-length fish -- are flat-out unconstitutional.

In 1993, the Delta smelt was listed as a threatened species under the Endangered Species Act. Pursuant to that same act, in December 2008, the Fish and Wildlife Service issued a "biological opinion" explaining the agency's view that the operation of the state and federal water pumps, located near Tracy, Calif., was jeopardizing the smelt's continued existence, and for that reason the responsible federal and state agencies had to cut back significantly on pumping and water deliveries.

As a consequence, millions of gallons of fresh water have passed through the Delta to the ocean, while the state's struggling economy endures a death blow from fields left fallow and farmworkers out of work, because not enough water is available.

Shortly after the biological opinion was issued, Pacific Legal Foundation filed a lawsuit in federal court in Fresno on behalf of three valley farmers, challenging the pumping restrictions as unconstitutional.

The suit goes to constitutional first principles. In our system, the federal government is a government of limited powers, meaning that the federal government can only do what the Constitution expressly allows it to do. Article 1 Section 8 of the Constitution lists a number of subjects over which Congress has legislative competence, among them the power to regulate commerce among the several states. It was pursuant to this power -- the Commerce Clause -- that Congress passed the Endangered Species Act in 1973, and pursuant to which the federal government argues that it can require the pumps to be turned off.

The feds contend that they can regulate the smelt because all activities in the U.S. that harm endangered species substantially affect interstate commerce. Even though the smelt may not be a commercial species, it is part of a larger class of items which do have commercial effects.

But the Commerce Clause does not go that far. The Supreme Court has held that, when adjudicating a Commerce Clause challenge, a court must look to several factors, among them whether the regulated activity is economic, whether the law in question has a "jurisdictional element" -- meaning some express tie-in to interstate commerce -- and whether the law contains congressional findings about how the activity affects interstate commerce.

Federal regulation of the Delta smelt fails on each of these factors.

Nevertheless, defenders of Delta smelt regulation counter that protecting the Delta smelt is essential to vindicating Congress' desire to protect biodiversity and all endangered species. The difficulty with this argument is that it would place no limits on congressional power to regulate any activity.

To be sure, some endangered species have significant economic value, and biodiversity writ large substantially affects interstate commerce. But any activity viewed at a high level of generality can be said substantially to affect interstate commerce. Moreover, to allow Congress to regulate a class of activities just because some of the activities within the class substantially affect interstate commerce would create the perverse result that Congress need only regulate more in order to regulate constitutionally.

For example, it is commonly held that the federal government has no power to regulate criminal activity generally. But there are concededly many crimes, such as theft and robbery, that have a strong economic component. It would therefore follow, under the logic of the Delta smelt's defenders, that Congress could enact a National Criminal Code because some of the crimes regulated substantially affect interstate commerce.

Using this reasoning, the federal-state distinction would be completely eviscerated.

Federalism is not an arid academic concept; it is a vital part of our constitutional government that serves to protect the rights of individuals from overreaching federal dictates. California has already suffered too long from the unconstitutional water cutbacks imposed by the federal government.

It is time to restore the constitutional balance and return the power to regulate California water issues to where it belongs: the people of California.

Damien M. Schiff is one of Pacific Legal Foundation's lead attorneys representing several San Joaquin Valley farmers in their challenge to the federal government's Delta smelt regulations.