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Wednesday, December 22, 2010

Thanks to the Obliquity of the Ecliptic

No, this is not an expression of gratitude for the holiday recess of Congress, rather it is an acknowledgement that our days in the northern hemisphere will (mercifully) be lengthening for the next few months due to the axial tilt of the planet.  Not that we'll feel much difference soon, but there is some comfort in knowing that things are improving.

As we're waiting for a midwestern warmup, the Sierras and Cascades are topping off their peaks with the water that will irrigate the gills of trout on the west slopes, before it spins the turbines to cool martinis and waters the grass of suburbia encroaching on the great valleys of the Sacramento and Willamette Rivers. A snow-pack of 10 feet on Donner Summit next spring won't be enough to start new glaciers, but will provide sufficient stream flows throughout the summer to ensure some headwaters survival of native trout.

Along the California coast, the Eel, Russian and Klamath Rivers will rise as much as 40 feet, carrying silt from hydraulic mining and clear-cutting scars over a century old and still in the adolescence of their recovery. Massive flows of water during coastal winters in primeval times provided migrating fishes access to headwater reaches. This, together with undisturbed forest soils that maximized retention time, provided adequate summer flows for juvenile fish habitat for coho and chinook salmon and coastal rainbow and cutthroat trout. Reduced summer flows and hydroelectric impoundments now limit the abundance and range of these species through increased temperatures and limited nursery habitat, leaving only remnants of the once-great runs of these anadromous fishes.

The contrasts are clear between western coastal seasonal runoff and the midwestern sequence of events. Mid-continental winter temperatures hold precipitation as snow and ice until spring temperatures begin a protracted period of snow-melt that raises river levels and floods low-lying river basins.  The midwestern drainages to the Gulf of Mexico and Hudson's Bay lowlands peak in late spring. But between then and now, our trout streams, while glazed over in places, will provide a winter fishery that will temper the passage of time until the caddis and blue-wing olive mayflies signal the onset of yet another dry fly season.

Have a happy holiday season, and may the New Year see multitudes of leaping trout testing your tippets!

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