9652 - Laserfiche WebLink

Home Browse Search

BULLETIN OF THE UNITED STATES FISH COMMISSION. Most. of the streams of Colorado rise in springs in or above the moantain meadows, many of them having their origin in banks of snow, which the clear weather of sum- mer is not sufficient wholly to melt. These streams are clear and very cold. In their descent from the snow-banks they are brawling and turbulent, often so much so as to be unfitted for fish life. Iu their course through the mountain meadows (very similar to the "Alp" pastures of Switzerland) the streams are usually of gentle current, with many windings and with occasional deep holes beloved of trout. Lower down most of them pass to the valleys through deep cafions, some of them very deep and with many rapids. Vertical falls are, however, very rare in Colorado; and most of these cafions form no obstacle to trout. Below the cafions, the stream, still clear and cold, enters the valley, where the flat: bottom is usually covered deep with sediment which the streams bring down. Herz the water grows warmer, the fine silt renders it more or less turbid, and at last it becomes nufit for trout and at the same time suitable for the suckers and chubs. In the winter and spring the wager is cold and clear for some distance down the val- leys. In these seasons the trout extend their range, to a corresponding degree. In the summer and fall they are more or less confined to the mountains or the cafions. Often the stream after entering the valley cuts its way through a moraine deposit. In that case its course is filled with boulders, and its waters are sometimes as brawling _in a boulder-strewn valley asin the mountains._._._ In some cases placer-mining and sump-mills have filled the waters of otherwise clear streams with yellow or red clay, rendering them almost uninhabitable for trout. i , Parts of the upper Arkansas and Grand Rivers have been almost rained as trout streams by mining operations. In a few streams the presence of iron springs seems to exclude all fishes. x - After reaching the bride of tl,e mountains the streams flow with`little current over the ill-defined beds across t6. plains. They tear up the fine soil find shit it from place to place. Occasional rains sitll the dry beds of 11 Sand-A?Toyos;" the stream be- comes more and more charged with clayey sediment, and in time not one of these rivers would be recognized ag the crystal-clear stream which came down the mount- ains._ The Platte spreads out broad and shallow over the plain, and its course is fall of quicksands. Its bau+;a are rarely well defined. The Arkansas resembles the Platte, being even more muddy, however, and the Rio Grande is similar to it. The Colorado carries the peculiar erosion of the mesas to a still greater extent as it goes southward. The stream is large and stift,_with_treac;h.e atis-currents---awl-shifting?brotrom - no rain-fall or frosts wear away its banks, it sinks deeper and deeper below the sur- face, until it forms the deepest gorge in the world, with banks which are vertical or like stair-cases. In the progress of settlement of the valleys of Colorado the streams have become more and more largely used for irrigation. Below the month of the cafions dam after dam mod ditch after ditch torn off the water: In summer the beds of even 'large rivers fas the Rio Grande) are left wholly dry, ail the water being turned into these , ditches. Much of this water is consumed. by the arid. land and its.vegetaLiQn; Le: ___: rest peeps back, turbid ahd ' e'lbw, ufA ttie bed of't} e stream to be gain.'intercepted as soon as enough has a&[,mulsted to be worth taking. Ir some valleys, as ill the flan Liriaa in the drY 'season there is scarcely a drop of water in the river-iced that hey 77 r