NOAA, the National Oceanic and Atmospheric Association, is predicting continued drought in virtually every Western state of the United States and in many of the states on the High Plains. Additionally, summer forecasts predict drier-than-average conditions for the Pacific Northwest, likely meaning drought for Washington and parts of Oregon.

Western Canada also labors under an extended drought. British Columbia is looking down the barrel of the worst drought since the Great Depression. Accumulated precipitation for lake levels in the province were close to the lowest figures of the 1920s. And the huge Okanagan Lake is as low as it was in the early 1900s.

During the time of great expansion into the American West, little thought was given to there not being enough water to meet the needs of the burgeoning population. To be sure, there were contentions over sharing water, but all thought there was enough to go around. In 1922, Arizona, California, Colorado, Nevada, New Mexico, Utah and Wyoming signed the Colorado River Compact, designed to share the water of the system proportionally. Along with a subsequent treaty with Mexico, it required the availability of 8.23 million acre-feet of water annually.

Any damming of the river was not to interfere with this figure, calculated by hydrologists at the time. But they miscalculated—greatly overestimating the water available in the system by more than double. In 1956, Congress authorized building the massive Glen Canyon Dam on the Colorado River, just above Lees Ferry, the halfway point between the Upper and Lower Basin regions.

The dam, which took as much concrete as it would take to build a four-lane highway from Phoenix, Arizona, to Chicago, Illinois, created the second-largest man-made lake (behind Lake Mead, also on the Colorado system) in the country, Lake Powell. The Colorado River Compact required the dam to release 8.23 million acre-feet of water a year, based upon the theory that the snow melt and tributary collections would deliver that much to Lake Powell.

In reality, the lake received less than half of that amount in most years, so it released over twice what it took in. That worked for many years, as long as the states did not use their allotments. But now, all the states on the system are demanding their full allotments and Lake Powell cannot meet the demands. It has dropped to 40 percent of its top capacity, exposing cliffs 10 stories high.

Congress may soon have to step in to resolve the growing "water war"—legal wrangling over distribution rights. An imposed federal solution isn't likely to leave any party happy.

The American West grew more in the past 20 years than ever before, but those were wet years, part of what turns out to be an unusual wet cycle. Comparing those 20 years to the last 800 years, scientists tell us that the wet cycle was a fluke. The climate patterns of the West typically feature extended drought conditions, punctuated by rare wet periods. So the abundance of rainfall during the 20th-century development of the West was an anomaly, rather than the rule.

Tree ring studies enable scientists to analyze the water patterns as far back as A.D. 900. Looking at dry versus wet years between 900 and 1300, research reveals that only a few times did water levels come anywhere near what they were in the 20th century.

In other words, the drought now hitting the West is actually the norm; the wet period was abnormal.