As a hydrologist for the National Forest Service, I’m constantly evaluating the rainfall we receive. We’ve had a pretty wet fall, winter, and early spring here on the Coconino National Forest.  In fact, if you look all the way back to this past summer with its very good monsoon, the last 9 months (ending in March 2019) puts this in the top 16 wettest for this period since weather records have been kept beginning in the late 1800s.

Compare this with the period beginning in July 2017 and ending March 2018.  That period was the 11th driest on record. Even worse is the time period beginning in August 2017 at the tail end of the North American monsoon (NAM) and ending in June 2018 just prior to the 2018 NAM.  That was the driest 11-month period on record!

So, is the abundant moisture over the past 9 months a signal that we are out of our long-term drought, and has this pulse of moisture undone the damage from the record dry spell of the year before?  The answer to the second part of the question is “nope”.  If I could answer the first part of the question, I probably wouldn’t be writing this article as I would be putting my predictive abilities to work earning tons of money.

Let’s tackle the first part of the question by starting with a quote from the Arizona State Climate Office’s website ( “Arizona is currently in our 21st year of a long-term drought.  Drought in the West is a long-term concept where a single dry year does not constitute a drought.  Since Arizona has an arid and semi-arid climate, extreme variability in precipitation is normal, and drought is characterized by a string of drier than normal years, often interrupted by a few wetter than normal years.  Currently most watersheds in the state have experienced only 7 or 8 normal or wetter than normal years during the past 21 years”.

Pay attention to the phrase “long-term concept”.  This really highlights the fact that one can’t really know where one is within a particular drought cycle.  Drought is a fact of life in Arizona.  Since the late 1800s, we have had 3 major statewide periods of drought including the one we are currently in.  Using tree ring studies, we can look back in time and find evidence for multi-decadal droughts worse than the one we are in. These significant periods of drought likely caused widespread migration of human populations.  It may be that there were other contributing factors in the disbursement of pre-historic southwest Native Americans, exemplified by the abandonment of major cultural centers such as Chaco Canyon and Mesa Verde, but drought likely played center stage.

One particularly alarming property of this latest drought is the combination of sub-normal precipitation with above normal temperatures.  Since 2000, mean monthly temperatures have been above normal every year, with 2017 being the warmest year on record.  Unfortunately, this is one prediction of a changing climate.  Even if total rainfall were to remain unchanged, increasing temperatures would effectively create drought conditions by increasing evapotranspiration with its consequent negative impacts on soil moisture, stream flow, reservoir storage, and groundwater recharge.

This gets to the second question about recovery from drought. One (or even several) good years does not make up for a string of bad ones.  One way to demonstrate this is by looking at reservoir storage on the Colorado River. Reservoir levels have been in fairly steady decline since 2000.  A few good years temporarily reversed the trend but certainly did not undo the loss of water storage in this reservoir.  If this keeps up, Arizona is likely to see its allocation of Central Arizona Project water being cut as part of Arizona’s recently passed drought contingency plan.  Closer to home, this certainly doesn’t make life easier for those desperately trying to restore forest structure in our nearby ponderosa pine forests before nature does it for us.

In addition, the long-term drought conditions reinforce the need to be constantly aware of the danger of fire, and to take the appropriate preventative measures: completely extinguish all fires when camping, never toss cigarette butts out of your vehicle, report any fires you happen across to 911 immediately, and just use common sense.

Serving Sedona, written this week for Friends of the Forest by Tom Runyon, US Forest Service Hydrologist, appears Wednesday in the Sedona Red Rock News.