Our home weather station says we’ve received 0.75 inches of rain so far this year. Patty and I are pretty sure we normally get at least 3 or 4 inches by now. None of us need a rain gauge to know we’re in a dramatically dry year. The lack of rain is making us all nervous.
Last week I spent some time with the Ryan Rowland (Data Chief) and Tom Marston (Investigations Chief) of the USGS Utah Water Science Center to find out what’s happening to our water supply this year. They showed me where I can get detailed historical information on streamflows as well current provisional streamflow data. The current data is almost “real time,” lagging by just 24 hours.
In the first six months of 2022, the total streamflow on the Virgin and Santa Clara rivers combined was 43,880 acre-feet. Is that good? Well, here’s the positive spin. Looking at streamflows for the first six months of each year beginning with 2006, this year was better than five other years and well above the 35,000 acre-feet in the first six months of last year.
That’s not saying much though. The average streamflow was 78,500 acre-feet for the first half of each year for the prior 16 years. This year’s flow is just 55% of the average. Can we catch up in the second half of the year? Anything is possible with Mother Nature, but it’s not likely. Over the past 16 years almost two-thirds of each year’s streamflow happened in the first half of each year. Streamflow was higher in the second half in only 5 of the 16 years. We may get more rain in the second half, but we lose the benefit of snowmelt.
Streamflow is one source of water. Another source is from the Navajo/Kayenta and Upper Ash Creek aquifer system right below our feet. Nobody really knows how much water is in this system that we might be able to tap. And whatever the answer is today, it’s fluid. Water moves. The last thorough study of this system was in 2000 but my initial read of the report still doesn’t tell me how much water is there. USGS is working on an update. But that won’t be done for a couple of years.
However, USGS does monitor well levels at 15 sites in Washington County. I have only just begun to look at the reports for them. The first one I looked at is a well southeast of Quail Creek reservoir. It doesn’t present a happy picture, but it’s just one of many sites.
The chart for this site shows that in 2004 water was at a depth of about 132 feet. The trend has been a downward one. This February the water level was about 142 feet. That means the water level in the well dropped about 10 feet in the past 18 years. My USGS contacts told me they believe most of the drop in water level is the result of human behavior, not climate issues. They told me Hurricane pulls water out of two or three wells in the vicinity of this monitoring well. Please keep in mind that I’m not a scientist, but this tells me that we are taking water out of this part of the aquifer faster than nature can replace it.
