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John Hollenhorst ReportingA new scientific study should be food for thought, perhaps even an alarm bell, to anyone who cares about our future water supply. It confirms that the recent drought is not unusual and suggests that unusually wet weather in modern times has given us a false sense of security.
If you want to guess the future, look to the past. At Dad's Tree Cutting Service you can see the past in tree rings. They tell us about water supply in the past and, with much less certainty, the future.
When water managers along the Colorado River plan for the future, there's one key issue.
Don Ostler, Upper Colorado River Commission: "We want to make sure that we don't have more people using water than can be supported through the most extreme drought."
Scientists have been trying to help by answering a key question: how much water naturally flows into the Colorado River? To get answers, they've opened the pages of history in tree trunks. Each ring is a year of growth. Wide ring, wet year. Narrow ring, dry year.
Since 1976, they've been examining trees throughout the Colorado River Drainage. They matched the data with the ups and downs of actual river flow in the 20th Century. Then they charted wet and dry spells back to Christopher Columbus. The studies indicate the 20th Century was unusually wet.
Don Ostler: "Well, in fact, the latest one that's been done is a little less worrisome than the one done previously."
Don Ostler says there are some uncertainties about the precision of tree ring data. But he says there is reason for worry because it shows at least eight droughts as bad or worse than the "Drought of the Century" we just went through.
Don Ostler: "That has got to be a red flag and a note of caution. And water managers need to factor that into their planning in terms of an appropriate contingency."
Six states divided the Colorado in 1922 based on river-flow expectations now recognized as overly optimistic. Big battles have been avoided because some states like Utah don't use all their water.
Don Ostler: "At full development, we will bump into that reality."
And that's the real lesson of the tree rings. At some point in the future, the growing West could bump into a drought that really hurts.
