In 40 years, most of New Mexico's counties, including Santa Fe, will face moderate to extreme water-shortage risks because of population growth and drought driven by climate change, says a new report by the California-based engineering firm Tetra Tech.

The report examined water supplies and demand in counties around the lower 48 states, using 16 different climate models. Researchers claim 1,000 counties will face water shortages by 2050.

The report, released by Tetra Tech and the nonprofit Natural Resources Defense Council, also looked at the risks to agricultural production.

The report supports what climate-change scientists have been predicting for the last few years — the Southwest will be vulnerable to drought and water-supply problems as climate change leads to higher temperatures and less snow.

In New Mexico, 19 of the 33 counties will be at severe to high risk of water shortages, according to Tetra Tech. Another eight are at moderate risk.

Many counties at the greatest risk of water shortages in California, Arizona and Nevada are supplied by the Colorado River, the report says. New Mexico also receives a share of Colorado River flows, delivered to the Rio Grande through the San Juan/Chama Project. That imported water is becoming an increasingly important source for Santa Fe as the city and county work to complete a project that will directly divert water from the Rio Grande. The city of Albuquerque already has begun drawing surface flows from the Rio Grande and treating it to drinking-water standards.

Tetra Tech calculated water demand based on predicted population growth and associated water needs. The supply was estimated based on current and future precipitation predictions using 16 global climate models.

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• To read the full report, visit http://rd.tetratech.com/