A 2006 New Mexico State University study by Ric Frost of the Lincoln National Forest highlights the impact of overgrown forests on water consumption in the drought ravaged west. According to the study, the forest historically contained 300 to 500 one-foot in diameter trees per acre. In the early 1990’s the U.S. Forest Service (USFS) eliminated all logging within the forest and tree density rapidly increased to a range of 1,000 to 5,000 trees per acre.
Experts say a one-foot diameter tree consumes an average of 50 gallons of water per day (gpd). By 2006, the average consumption of water in the forest conservatively grew to 50,000 gpd per acre, compared to the 20,000 gpd consumed in the pre-1990 healthy, logged forest. The Lincoln forest contains 24% or approximately 265,000 acres of timber-grade lands, not counting the 66% of lands densely populated with pinion and juniper trees—also notorious water hogs. Those overgrown timber lands now consume approximately 13.25 billion gpd, which equals 40,662 acre feet per day or, 14.8 million acre feet of water per year in a portion of one forest!
The 1897 Organic Act of the USFS lists only three purposes for which Congress established national forests: “to improve and protect the forest within the reservation,… securing favorable conditions of water flows, and to furnish a continuous supply of timber….” In recent years the USFS has implemented policy for much of its 193 million acres of national forests contrary to the intent of Congress. Since the Forest Service has stopped logging on lands it manages, most western forests now contain timber loads comparable to those found in the Lincoln National Forest. This mismanagement has resulted in a major environmental debacle—springs and streams have stopped flowing; overgrown forests are riddled with disease; wildlife populations are diminishing; and, increased fuel loads have set the stage for more catastrophic fires.
The obvious conclusion to be drawn from the Lincoln National Forest study is that overgrown forests are also contributing significantly to the western drought conditions, contrary to the USFS charge to protect water flows. Perhaps drought ravaged municipalities such as Phoenix and Las Vegas need to look upstream to the watersheds managed by the Forest Service and demand the USFS follow the intent of Congress to help solve the West’s water shortages.