Our unquenchable thirst for fossil fuels is costing us more than five-buck gas. It is costing us our Appalachian Highlands.

Right now, our lust for coal dust is blowing the tops off mountains; the dynamited rock that used to be ridge line is bulldozed into valleys and buries more miles of streams and more brook trout than I can stand to ponder.

Meanwhile, the hottest natural gas play in the country, the Marcellus Shale formation, is propelling big trucks and big money along the winding mountain roads of West Virginia, western Maryland, Pennsylvania and southern New York. The men behind the trucks are looking for places to accommodate well pads, compressor stations and waste disposal facilities, turning good woods to factories along the way.

Our mining practices not only replace landscapes populated by animal sound and the whistle of the wind with the grind and hammer of heavy industry. They also replace the things that absorb carbon with things that emit it. This is, of course, the opposite of how we are supposed to deal with human-induced climate change, perhaps the biggest threat to our mountains.

In both aforementioned cases, economic concerns and a perceived scarcity of resources are trumping our respect for intact natural systems. But there are problems with the ways we calculate the costs when we look at whether and where to drill or mine. Most price tags do not include the down-the- line costs that come from lost opportunities-economic and environmental-that accompany the production.

What are we failing to take into account? Well, according to an EPA assessment, the costs of mountaintop removal should include the loss of more than 900 miles of streams now buried forever. This loss adds up to costlier water treatment for communities downstream. It means lost revenue to state and local coffers when would-be fishermen stop buying licenses and visiting the area.

The latest chapter in the scientific inquiry into the downstream impact of mountaintop removal looks at a tiny indicator of water quality, the mayfly.

Mayflies make up a big chunk of the insects in the waters of the East. About 630 species inhabit North America. After spending a year underwater as a nymph, the average mayfly emerges and lives from a couple of hours to a couple of days. Mayflies are sensitive to pollution, making them good indicators of overall water quality. And trout love 'em, so we want and need lots of mayflies.

Sadly, two EPA scientists confirmed that far fewer mayflies live in waters downstream of mountaintop removal sites. Perhaps not surprisingly, they also found greatly diminished water quality. I'm guessing that if anyone cares to look, they'll find fewer fish, too.

The full body of research is to be published later this year. But one of the scientists, Margaret Passmore, said in an agency press release, "While habitat degradation from mountaintop mining is what one sees on the surface, we found that chemical effects are quite pronounced and limit much of the expected biodiversity from what were once naturally rich, diverse Appalachian stream systems."

The EPA assessment has been the focus of intense debate and accusations that its scientific conclusions are being watered down for political ends. It was hard for me not to notice, for instance, that since I read an earlier draft of the report, the EPA dropped the total number of miles of streams estimated to be buried by mountaintop removal by 300 miles.

Given the increasing demand for coal and gas, the approximately 1,000 miles of streams that have disappeared are just the tip of the proverbial iceberg. When you recognize that gas drilling has only just begun in the region, you'll begin to understand that we are about to lose many more miles of streams.

For proof, I point to the Intermountain West, where oil and gas development has also altered landscapes in irreversible ways. Remote parts of Wyoming near Yellowstone and Grand Teton national parks are experiencing their first-ever air quality warnings. Some of the country's finest spring creeks now have trucks and rigs rumbling along their banks. And if you venture into parts of New Mexico, you'll cough for a week after breathing the waste gas emitted by the drilling operations.

This is not the future we want for our highlands. Nor is it one we should tolerate. To change course, we must change our lifestyles and use fewer non-renewable resources whenever and however possible. And we must pressure our policy makers to make sure that when they calculate the cost-benefit ratios for our energy sources, they take the true costs into account, mayflies included.