The Washington County Water Conservancy District (WCWCD) released a new Impact Study two weeks ago. It shows WCWCD is currently using more than 90% of its annual “reliable” water supply of 64,099 acre-feet per year.
The study expects WCWCD to add an additional 3,000 acre-feet of supply, but not until 2025 and 2026 with the Ash Creek and Sullivan Wells projects. Nothing before and nothing after, until 2035. That’s when WCWCD is still planning for the Lake Powell Pipeline to become a reality. Really?
The current “excess” capacity of about 660 acre-feet could service about 1,300 new homes. Ivins alone has more than that in the works.
The Impact Study reports that, “With no additional supply, existing sources will fall short of demand around 2023, even at the proposed reduction in the level of service for new users.” The study extends that date to 2028 if “the planned future water supplies excluding Lake Powell Pipeline are constructed in that timeframe.” Timeframe means the expected delivery dates of 2025 and 2026, but that still leaves an awkward gap in 2023 and 2024.
The additional supply of 3,000 acre-feet expected in a few years would hydrate about 6,000 “equivalent residential connections” (ERCs). But the Impact Study estimates there will be demand for 34,000 more ERCs in the next 10 years. What to do?
Well, a 1993 report, imaginatively titled “Utah State Water Plan: Kanab Creek/Virgin River Basin,” had some answers. It recommended low flow devices and fixtures, secondary systems to homes, xeriscaping for new construction, and increased water pricing, saying that current low water prices provide little, if any, incentive for the consumer to conserve water. That was almost 30 years ago.
Great advice! We really should do all of that, shouldn’t we? And hopefully not take another 30 years to think about it. In the meantime, let’s look at our current water supply to get a better understanding of how reliable it is.
Our Rivers
In the 12 months ending September 30th, the streamflow on the Virgin and Santa Clara rivers totaled just over 95,000 acre-feet. That beats the previous 12-month total of just under 72,000 acre-feet. And it is in-line with the median streamflow of 96,000 acre-feet since 2006.
Is being in line with the longer-term streamflow good? Karry Rathje, with WCWCD, points out that, “Although this water year may be similar to other water years in the last 15 years, we have about 40% more people relying on our supplies than we did in 2006.”
The average streamflow is higher than the median, at 122,000 acre-feet. That’s due to some years with exceptional monsoon rains. Those rains are not as helpful as you might think. Karry points out that high river flows must often be bypassed at the Quail Creek Diversion to prevent sediment from filling the transmission pipelines. So, the duration of high flow events affects how much water can be captured and made available for use. Because of this, annual average flow rates are not the best indicator of water availability.
The goal is to determine a “reliable” flow for the rivers. I met with Zach Renstrom at WCWCD last week and he’s using 60,000 acre-feet a year as the reliable flow for the Virgin River. That’s less than any 12-month period over the past 17 years. The closest we came was in June 2021 when the flow over the prior 12 months was just under 63,000 acre-feet. So, 60,000 acre-feet seems conservative and pretty reliable… as long as Mother Nature isn’t fickle.
Reservoirs
WCWCD’s five reservoirs in Washington County can hold almost 109,000 acre-feet of water. More are coming. On top of that potential capacity, WCWCD estimates 100,000 acre-feet have seeped into the aquifer below Sand Hollow. Pumps are in place to use that water if needed, but that’s a last straw event.
The amount of water in our local reservoirs has fallen by 5,000 acre-feet in the past 12 months. In the previous 12 months it fell an additional 4,000 acre-feet. Oops. It looks like we’ve been dipping into our savings account to balance our budget. That’s not good. I mentioned to Zach that I interpret those drops as a raid on our emergency savings account and it suggests that all of our water sources have been insufficient to meet even current demand, at least in the past two years. He didn’t disagree.
Reservoir levels bounce around a lot during any year, increasing in the winter and spring and decreasing in the summer and fall. A better way of looking at water trends in our reservoirs is on a 12-month moving average basis. That’s the chart below.
Karry told me that the amount of water stored in our reservoirs has been declining for four years. Similar declines occurred in the 2006-2009 and in 2011-2015 timeframes. She also noted that although it is early in the water year, which started October 1st, there are indications that it may be another average/below average year. She said that WCWCD is concerned that our reservoirs may end the year, next September 30th, at record low levels.
Groundwater: Aquifers/Wells
Let’s go back to that 1993 report to see if it had any other good advice. It did. The report pointed out that, “In general, irrigation water needs exceed supply. This accents the need for wise management and conservation of water. Monitoring of groundwater storage would be imperative to prevent mining.”
The USGS lists 50+ wells in Washington County, but only 15 had data for 2022 and historical annual data going back at least 10 years. That’s frustrating, but Zach Frankel, the Executive Director of the Utah Rivers Council, warned me about this when I began this research, saying, “Groundwater science is often archaic and usually underfunded.” So much for paying attention to good advice.
Twelve of the fifteen wells experienced a decline in water level since 2013. This trend suggests that these wells are being “mined” rather than “harvested.” The wells are monitored at the same time each year, so changes are not the result of seasonal trends. But Wayne Pennington, an Ivins resident who was a Dean of Engineering and Professor of Geophysical Engineering, told me that the problem is that, unless a very careful experiment is conducted with the wells, it is difficult to tell if the water-level declines in any well is due to an aquifer-wide decline or is just a decline located near the well itself.
The problem wells are in Enterprise, Desert Canyon, and around Hurricane. The water level in the six wells I was able to measure in these areas dropped about 12 feet over the past 10 years. The three wells in Enterprise dropped the most. That’s not due to population growth. The state simply allowed too many wells that have been used to expand alfalfa production significantly. Realizing the problem, water rights are being terminated, with the most junior ones starting to expire in about 5 years.
Earlier this week I met with one local farmer who said even his water rights in the Enterprise area, which his family has had since the late 1800s, will be terminated in about 60 years. He also said that he was not able to get all the irrigation water he had rights to from Gunlock and had to pay extra for pumping water from St. George wells. WCWCD confirmed that was a problem. Users were entitled to about 1,000 acre-feet but ended up with less than half of that, even with the additional well water.
So, he had to leave some fields dry this summer. And that’s become a more common problem in recent years. He noted that although leaving fields without water resulted in lost revenue, it’s less of a problem on a farm than it would be in a subdivision.
All of this underscores the importance of following the advice from that 1993 report. So why aren’t all the wells being monitored? I talked to Ryan Rowland, the Data Chief at the USGS Utah Water Science Center. He said they are losing monitoring sites in rapidly growing areas. But sometimes they are denied access to sites. But he said they are always interested in adding new wells to monitor. Based on the trend shown here, our persisting drought, and continued rapid growth, we need to monitor all the wells in the county.
Next Steps
This won’t be my last post about water. There’s more coming soon, thanks to a lot of information I have received in the past few weeks from a number of people, including: Zach Renstrom, General Manager, Washington County Water Conservancy District; Karry Rathje, Communications & Government Affairs Manager, Washington County Water Conservancy District; Wayne Pennington, Dean of Engineering and Professor of Geophysical Engineering Emeritus; Michigan Technological University; Ryan Rowland, Data Chief, USGS Utah Water Science Center; Tom Marston, Investigations Chief, USGS Utah Water Science Center; Zachary Frankel, Executive Director, Utah Rivers Council; and Ed Andrechak, vice President, Conserve Southwest Utah.
Please share your comments on this topic and tell me about other Ivins issues
I have not addressed in recent posts. Email me at Mike@MikeScott4Ivins.com.
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