Bathtub Ring Around Lake Powell
April 12, 2017
Shown above is the bathtub ring that surrounds Lake Powell, Utah. It's the broad mineral-covered swath of white at the base of the cliff. This band is seen all along the lake and reveals the area that was covered by the lake when at its peak level—nearly 100 ft (30 m) higher than today.
Lake Powell reached capacity (at the 3,700 ft or 1,238 m level) in 1980. The statistic about the bathtub ring is updated continually and at the time of this writing is less than half capacity—at only at 47.79 percent. The steadily decreasing lake level is caused not only by evaporation in the windy, arid environment (exacerbated by the past 17-year drought in the Colorado River Basin) but also by the steady overuse of the Colorado River systems and the seeping of water back into the fissures at the bottom of Glen Canyon. The combined water loss from evaporation and seepage equals 280 billion gallons annually.
Note the fingers of land protruding into the lake. They were shaped by deep, stream channels that were cut prior to the formation of the Rainbow Bridge. Also noteworthy are the vertical streaks of desert varnish, visible on nearly all of the rock faces. Photos taken August 21, 2016.
Photo Details: Camera Maker: SONY; Camera Model: DSC-RX100M4; Lens: 8.8-25.7mm ƒ/1.8-2.8;
Focal Length: 19.29mm (35mm equivalent: 53mm); Aperture: ƒ/5.6; Exposure Time: 0.010 s (1/100); ISO equiv: 125.