Yesterday, in Part Three of this editorial series, we considered an inventory and analysis of irrigation ditches in Archuleta County, summarized last week at a Zoom meeting hosted by the Upper San Juan Water Enhancement Project (WEP).
San Juan Conservation District Manager Cynthia Purcell and a team of researchers had documented agricultural ditches and irrigation systems, and proposed an $8.8 million price tag for bringing the ditches and irrigation systems up to better condition.
Ms. Purcell had also revealed that, of the 5,329 acres of irrigated ranch property inventoried, about 4,664 acres — about 87% — was still using a relatively inefficient irrigation system known as ‘ditch irrigation’. That type of irrigation, she explained, was only about 30%-50% efficient.
For the purposes of this article, I’m going to average those two numbers. Call it 40% efficient.
About 13% of the remaining acreage — about 683 acres — was using ‘gated pipe’ irrigation, which we were told is about 50%-60% efficient. So let’s call it 55% efficient, on average.
Only 27 acres of Archuleta County agricultural land is irrigated with sprinklers, with an efficiency of 70%-75%.
Although Ms. Purcell did not give us data about how much total water we are talking about here, we can reference some 2015 data provided by the US Geological Survey. That website suggests that our agricultural industry uses about 47,000 acre-feet annually, or roughly 36 times the amount of water sold by Pagosa Area Water and Sanitation District (PAWSD) to its customers each year.
If we had $8.8 million in a piggy bank somewhere, and were willing and able to fund the repairs and improvements suggested by Ms. Purcell and her team… what would that mean for Archuleta County’s water picture?
If 87% of the community’s agricultural land uses ‘ditch irrigation’ (40% efficient) but could be upgraded to ‘gated pipe irrigation’ (55% efficient)… hmmm.
Since their irrigation systems are only 40% efficient, those 4,664 acres might in fact be using closer to 90% of the community’s agricultural water. We don’t know, at this point. We seem to be at the very beginning stages of wrapping our heads around how water is used (sometimes inefficiently) in Archuleta County.
If 90% is a good number for the percentage of water used by the least-efficiently-irrigated ranches, that would be about 42,000 acre-feet used on those ranches, in a typical year. According to my pocket calculator, switching every ‘ditch irrigation’ system to a ‘gated pipe’ irrigation system would reduce the amount of water used by agricultural users who are currently using ‘ditch’ irrigation by about 28%.
In theory, that could reduce the water diversions by our local agricultural industry by about 12,000 acre-feet per year. To put that number in context, that’s about 9 times the amount of treated water sold annually by PAWSD.
This number is especially interesting to me, because it doesn’t imply any reduction whatsoever in the amount water effectively applied by our local ranches; it merely means a more effective application. No reduction in crop yields, no change in the type of crops grown… only more water left in the river, is the implication.
Note that we did not even consider the amount of water that could be saved if our ranchers switched to the even more efficient ‘sprinkler irrigation.’
Nor does it take into account possible water savings created by repairs and upgrades to the ditches themselves.
I find these numbers to be rather useful in understanding how the distribution of Archuleta County water might change in the coming years. I currently serve on the San Juan Water Conservancy District (SJWCD), a taxpayer-funded agency that has been working for at least two decades on the so-called Dry Gulch Reservoir Project — also known, by some, as the San Juan River Headwaters Project.
That project is sometimes envisioned as an 11,000 acre-foot reservoir, that would divert water from the San Juan River for purposes that have not yet been fully defined.
Note: Although I currently serve on the San Juan Water Conservancy District board of directors, this editorial series reflects only my personal perspectives and opinions, and not necessarily the perspectives or opinions of anyone else on the SJWCD Board.
The cost of building the reservoir has been variously estimated at between $60 million and $100 million. Because this is a public water project (as currently envisioned) the assumption is that Colorado taxpayers would fund all or most of the project.
Thanks to the work of the WEP, we now have access to data related to a different type of water project. If my pocket calculator is correct, it appears to me that an investment of $8.8 million on ditch repairs and improvements, and upgraded irrigation systems, within our community, might produce 12,000 acre-feet — or more — of conserved water, per year.
Or… we could spend $60 million to build a reservoir capable of holding 11,000 acre-feet, per year.
These are two options that the community might consider. There may be other options to consider as well, as we look at the future of water in Archuleta County.
But we haven’t yet listened to the fourth presenter at the WEP’s March 31 Zoom presentation: Seth Mason of Lotic Hydrological, based out of Carbondale, Colorado.
I had to look up the definition of ‘lotic’, pronounced “low-tic”.
lotic (ˈləʊtɪk)
adj : Of, relating to, or living in flowing water.
Once upon a time, the water that flowed down the San Juan River and its tributaries was seen primarily as an agricultural resource, to be used mainly for growing grass and hay for cattle and sheep. Later, as the town of Pagosa Springs grew and expanded, folks became more concerned about municipal uses.
During this period, some people also saw the rivers and streams as great places to go fishing. But that was perhaps a less important use of the water, at the time.
Over the past couple of decades, the Town of Pagosa Springs has invested millions of tax dollars into promoting tourism and recreation, and we’ve seen the growth of a ‘rafting and inner-tubing’ industry along the downtown stretch of the San Juan… and recreational use of the rivers for fishing has also grown in importance.
So let’s consider what hydrologist Seth Mason was able to tell us about ‘flowing water’…