Drought has been shrinking or drying reservoirs throughout the West for so many years that it has rekindled a debate over the basic water rules of the region.

The rules are codified in the "law of the river," the Colorado River Compact, which guides distribution of water flowing through seven states and parts of Mexico. The region covers 244,000 square miles, according to a fact sheet posted on the Internet by the group Friends of Lake Powell.

The compact, ratified by Congress in 1922, allocates water among the seven states. Utah, Colorado, Wyoming and New Mexico make up the Upper Basin states, while California, Arizona and Nevada are the Lower Basin.

Upper and lower basins each are entitled to 7.5 million acre-feet of water per year (with several complicating factors). The Upper Basin is required to deliver 7.5 million acre-feet yearly to the Lower Basin.

In the Upper Basin, Colorado gets the lion's share of the water at 51.75 percent of available supply. Utah is next with 23 percent, and the remaining states are entitled to less.

Farmers, ranchers, the environment, recreationists and others who champion competing uses for scarce water have sparked new proposals for changes in water allocation.

In a May 6 New York Times article, Dan McCool, University of Utah political science professor and director of the U.'s American West Center, called for scrapping the law of the river as hopelessly obsolete. He told the Times the compact is built around an agrarian West that no longer exists and is based on a hydrological fallacy.

Few if any water experts dispute that the 1920s estimate of the Colorado River flow, the basis for allocation figures in the compact, is wrong. According to Friends of Lake Powell, the compact estimates the Colorado River flow at 17 million acre-feet per year, while a more accurate figure is closer to 13.5 million acre-feet.

Most years, the river may not have the 15 million acre-feet envisioned by the compact as being divided between the basins. But should the compact be rewritten?

Beyond recognizing the error of the earlier estimate on available water, the two sides of the issue have little common ground.

In separate interviews, the Deseret Morning News probed the thinking of two of the foremost thinkers on the law of the river, McCool and Bennett Raley, the assistant secretary of the Department of Interior for water and science.

Outdated compact?

McCool: "(The compact is) based on a hydrological fallacy. It was obsolete the day it was signed, and it has become an albatross. It's hopelessly archaic."