Me: What's that double mountain over there?

Joe: Double Mountain.

Me: Oh.

Joe: As in the Double Mountain Fork of the Brazos River.

During a previous trip, we had traced the mighty Brazos from its double mouths near Freeport to a small Double Mountain Fork lake under the Cap Rock near Laredo. Although hydrologists will tell you that the Brazos, like the Colorado, rises near the New Mexico border, there is little water in those watersheds on the tortilla-flat Llano Estacado. Instead, the tributaries of both great rivers begin to flow normally in the dramatic canyons below the High Plains.

First water in the White River Floydada just below the Cap Rick. Marker says Coronado camped here. Wind is up today.

When they flow at all. On our most recent Texas River Tracing, we followed three forks of the Brazos — White, Clear and Salt — having already done the Double Mountain on that earlier voyage. We were warned by guidebooks that, because of constant pressure on the Ogallala Aquifer, the White River is almost a thing of the past. In modern memory, it was a rushing stream with abundant fish. We discovered almost no water until we reached the small, out-of-place White River Reservoir just above its juncture with the Salt Branch.

It happens again and again out here on the border between the Llano Estacado and the rolling plains to the east. It's flat, flat, flat, flat, flat, then we plunge into a rugged canyon with only a "Falling Rock" sign as a warning. It happened just south of Floydada for the White. There we found some puddles in a grassy ravine near a roadside park with multiple historical markers. Among the boasts of this little valley is that ranchers found what was believed to be Spanish chain mail nearby, suggesting that Coronado and his far-flung expedition camped here. Well, it's possible.

In another deserted canyon of the White, we encountered a lonely, well-accoutered ranch house accompanied flying the black-and-white "Come and Get It" flag copied from the Battle of Gonzales. The image with a cannon has been appropriated by Tea Party types, which made us laugh. Here was a house many miles from anywhere with a perfectly maintained Ranch to Market Road that comes right up to its driveway. Something tells me that other Texans helped pay for the FM.

Below the White River Reservoir — no boats here either — we stumbled on several gorgeous crossings of the Salt Branch of the Brazos River.

First water of the Salt Branch Of the Brazos River in Kent County.

In contrast to the White, it runs freely and colorfully through stone-walled canyons.

Abundant wildlife on an exquisite December day.

The Salt Branch if the Brazos River goes through some gorgeous red canyons.

We took it for granted that it would taste salty, since we tested the Brazos downstream on a previous trip.

The Salt Branch of the Brazos River near where it empties into the Double Mountain Fork.

(The next day, we coursed back around to pick up the Salt near its juncture with the Double Mountain.)

That left the Clear Fork. Author John Graves, who died in 2013, celebrated this hardwood-lined tributary at length.

The Clear Fork of the Brazos River north of Noodle, TX

I think he would be saddened by what we witnessed.

The Clear Fork of the Brazos River widens and deepens at Hawley.

This is a prairie river that plows through farmlands northwest of Abilene. We criss-crossed it on county roads, only to find its low, strong flow interrupted by agricultural and industrial rubbish. Some beautiful stretches remain, but few of them we'd call "clear."

Pretty much near the end of the road for the Clear Fork of the Brazos River at Lake Fort Phantom Hill, which is formed by Elm Creek, a tributary of the Clear.

The fork led us to muddy Lake Fort Phantom Hill, named for a 19th-century outpost on the Clear. We didn't visit the fort site, but we examined the cliffs above this sizable lake which, perhaps because of the clement weather, was the first with any observable winter recreation on this trip. Impounded in 1938, it's actually formed by Elk Creek, one of the Clear's tributaries. The Clear meets the rest of the Brazos near South Bend in Young County.

As we drove into Abilene for the evening, we noticed the odd placement of a giant auto salvage yard and the city's sanitary landfill uphill of the lake, which presumably provides water for this home to 100,000 folks.