The Endangered Species Act celebrated its 40th birthday Saturday, and 40 years in, its impact remains a decidedly mixed blessing.

The ESA has some real wins to its credit. The bald eagle surely is high on that list. The widespread use of the insecticide DDT had reduced the number of breeding pairs of the national bird to just over 400 by 1963; it was declared endangered five years later and was one of the first species to receive protection after the ESA became law.

Just before the listing, DDT was banned, and the listing itself provided much-needed protection to the bird. It was removed from the ESA’s protection list in 2007, according to the Associated Press.

So far, protections for the northern spotted owl have proven not terribly effective. Years after being listed, its numbers continue to decline, and now officials are shooting barred owls in the attempt to rehabilitate its threatened cousin.

Measuring the other side of the ESA is more difficult, unfortunately. Most of the act’s negative impacts have been felt locally, in areas where threatened and endangered species are found, and they generally don’t get the sort of attention the species themselves receive.

One such attempt came in 1998 in a paper by Gardner M. Brown Jr. and Jason F. Shogren in the Journal of Economic Perspectives. Brown, from the University of Washington, and Shogren, from the University of Wyoming, said estimates of declining economic welfare in the region ranged from about $33 billion to $46 billion in 1990 dollars.

In other terms, those estimates included more than 28,000 jobs lost by the year 2000, and, over the long haul, the value of timber uncut because of the owl. The folks in Curry County, you can believe, will give you no argument over those bleak numbers.

We’ve long suspected that the economic impacts of Endangered Species Act listings would get more attention if they were felt nationwide, but that has yet to happen. The folks in Washington, D.C., and New York can look with pride at the bald eagle in all its recovered glory. They’re less likely to notice Curry County, Ore., a county near bankruptcy brought on in no small part by the same law that saved the eagle.