Utah scientific: Worse droughts ahead?

Utah is in for longer — and worse — droughts, predicts a new scientific report.

"Drought in Utah: Learning from the Past — Preparing for the Future" was issued this month by the state's Division of Water Resources. A dozen experts from the division prepared the document, with Brian King as the primary author.

The report emphasizes the need to diversify water supplies in order to mitigate future droughts. It praises Salt Lake City for taking such measures, ensuring a reliable supply.

"Drought can never fully be mitigated and an element of 'coping' or 'living with drought' will always exist," it points out. But action can lessen the severity of coming dry cycles.

A surprising finding is that for more than a century, Utah has enjoyed an unusually stable climate.

That is the same period during which many scientists have claimed human-caused global warming has accelerated. But whether this phenomenon — if it actually exists — missed Utah or its effects aren't fully felt yet in the Beehive State — or if it is actually beneficial to the state — the fact remains that the past 111 years of instrumented weather records show unusually good water supply.

However, droughts "occurred years and millennia before the start of monitoring and recording climatic/weather conditions," the report notes.

Dendrochronology, the study of tree rings, lays out tangible evidence of year-by-year weather conditions stretching back more than 2,000 years. The width of tree rings, reflecting trees' yearly growth, tell of wet or dry conditions.

"Analysis of this record indicates that many droughts, before the advent of the instrumental record, were more severe, more frequent and impacted larger areas," the report states.

"On average, drought contained in the reconstructed ... record (roughly 1,900 years before the instrumental record) was approximately 10.9 years in length compared to the average drought duration of 6.8 years during the last 111 years (instrumental record)."

Other methods of determining past conditions, such as studies of lake sediments, reinforce the conclusion, it says.

"Research indicates that prolonged dry periods have occurred in greater frequency than has been experienced within the past century."

Coupled with evidence of climate change, it adds, episodes similar to past conditions will probably happen again. In other words, there will be droughts that are "more severe and longer duration" than experienced in the past 100 years.

State water experts have written a "Pre-Disaster Mitigation Plan" addressing drought and other natural hazards. But "Drought in Utah" calls for "more drought specific planning and action."

Suggested mitigations include transfer of water by a water banking system from willing sellers to willing buyers during drought; "conjunctive management" of groundwater and surface water; interconnecting water systems; new water developments; reusing treated waste water; managing water demand; metering use and detecting leaks; weather modification; and a drought early-warning system.

Randy Julander, a premier water supply expert and a member of the panel that reviewed the report, said the study was "extremely well-researched and has some really big lessons" for Utah.

The snow survey supervisor for the U.S. Natural Resources Conservation Service in Salt Lake City, he said many people have relied on the historical record of observed snowpacks, precipitation, temperature, etc. They show years of plentiful water and years of drought, he added.