Smoke from the High Park fire seen from Fort Collins, Colorado, on June 17, 2012. National Guard

Fly fishermen have always been natural citizen scientists; it’s our business to know the seasons, to know from the appearance of certain spring flowers when a particular insect will emerge from its nymphal or pupal form and take flight. We time our trips to the river according to the arrival of specific mayflies and caddisflies.

On the Housatonic River in Connecticut, one of my favorite trout streams, we wait eagerly for Ephemerella subvaria, better known as the Hendrickson, the first great mayfly hatch of the season, which generally shows up in the fourth week of April and runs into early May. Except that this year, the first Hendricksons arrived on March 28^th. We’ll have to stop calling them mayflies, I said to one of my fishing buddies. That’s nothing, a friend who lives in upstate New York told me in an e-mail: she had seen fireflies this year on May 7. Normally we don’t get them in these latitudes until late June.

I should have borne all this in mind when I flew out to Colorado earlier this week. When I plan a trip, my packing list tends to include a note that says, take fly rod? Usually I’ll check with the U.S. Geological Survey to see what its stream gauges have to say about current water levels on the local rivers where I’m going. But flying out to Colorado in mid-June, it never even crossed my mind. Fly fishing in the Rockies at this time of year is out of the question; the rivers are always blown out by runoff from spring snowmelt.

So it came as a shock when I drove through the beautifully sculpted glacial Kawuneeche Valley on the west side of Rocky Mountain National Park and saw dozens of fishermen casting their flies on the upper Colorado River, in water that was as shallow and clear as it usually is in late August. When I got back to my hotel that night, I checked the USGS numbers for this section of the river. According to 30 years of records, it was running at less than one-sixth of the mean flow for this date.

Crossing Trail Ridge, which at 12,183 feet is the highest pass in the park, I cursed my lack of foresight: no rod, no flies, no waders, all those big browns and rainbows I might have caught. But no matter: the views were spectacular. Or at least they were until the road wound its way down through the town of Estes Park and a thin gray haze appeared over the foothills of the Front Range. That was when the penny dropped: no snowmelt, fishermen out in June, tinder-dry forests. A major fire.

For the rest of the week I followed the course of the fire in the Denver Post. It had begun with a five-acre burn from a lightning strike 15 miles west of Fort Collins. On the third day, I was staying with friends in Golden, 70 miles to the south; next morning all of us awoke complaining of dried-out sinuses, congestion, burning throats. By the following day the High Park fire, as it’s known, had become the third largest in Colorado history; relief teams of firefighters were being flown in from Montana. As I write on day nine, it has burned about 86 square miles -- and it is still growing, with 50-mile-per-hour winds now driving thick plumes of smoke over Fort Collins.

The High Park fire is now 40 percent as large as the legendary Hayman Fire of 2002, the biggest in Colorado history. But the story is far from over. The underlying conditions are much more worrisome than they were ten years ago. The remaining snowpack in Colorado is at two percent of the average for mid-June. By the time the High Park fire caught hold, 19 other major wildfires were already burning in nine mountain states. State officials were warning that the High Park fire might burn into the fall, advising residents from the Wyoming border down to Colorado Springs to avoid outdoor activities, fretting that the state’s $10 billion tourist industry could be at risk. Most alarmingly, the fire was in imminent danger of spreading westward into a vast wilderness area where 70 percent of the forest has been killed by the mountain pine beetle; this pest's northward movement through the Rockies, the consequence of rising temperatures, has turned the pines into parched skeletons.

In August, I plan to make my annual pilgrimage to Montana and Wyoming. I’ll pack my fly rod for sure, and I’ll pay closer than usual attention to those USGS stream gauges. In a year like this one, when nothing is normal, I have no idea what to expect. Perhaps my favorite rivers -- the Lamar, Rock Creek, the Yellowstone -- will be dried-up trickles. Perhaps they will be blown out by freak summer storms. Or perhaps, God forbid, they will be lined with blackened pines and choked with ash and dead trout.