IMAGE: A proposed ‘off-stream reservoir’ in Canada.
For example, during the most recent drought of record, studies have shown that the Highland Lakes [surface reservoirs near Austin, Texas] lost almost as much water per year due to evaporation as the entire city of Austin used per year. The water loss from evaporation even exceeded the city’s use in the worst drought year, 2011, by 25 percent…
— from a 2017 article by Jennifer Walker on Texas Living Waters website.
The title of this editorial series derives from a comment posted to Facebook by San Juan Water Conservancy District (SJWCD) board member Rod Proffitt. He wrote, in part:
“Just read the [Pagosa Springs SUN] article on the PAWSD meeting. It is the furthest thing from responsible journalism to give the worst among us a forum that misleads the public…”
The “worst among us” in this statement appears to refer to the Pagosa Area Water and Sanitation District (PAWSD) board of directors… which is a bit awkward, considering that PAWSD and SJWCD are supposed to be partners in a proposed water reservoir project known as the Dry Gulch Reservoir.
Many people in the water industry will tell you that water reservoirs are the best thing since sliced bread.
This installment is going to include some amateur calculations, mainly because we have no professional calculations available. (In my experience, amateur calculations are sometimes better than professional calculations done by people working in the water industry.)
When I visited Google.com earlier this week, I was presented with a list of 43 million websites that are somehow related to the search phrase, “Environmental Impacts of Reservoirs”.
Pretty much any human-driven project will have both positive and negative effects on the environment. How do ‘reservoirs’ fare, in that regard? Generally speaking?
I perused the top 40 search results delivered by Google and discovered that, generally speaking, there are quite a number of well-recognized negative environmental impacts from reservoirs and the dams that create them, including:
- Harmful Effects on Aquatic Animals
- Hindered Fish Migration & Damage to Spawning Grounds
- Altered, Unnatural Water Temperatures
- Erosion of River Beds
- Sediment Accumulation Risk
- Erosion of Surrounding Soil
- Impacts on the Groundwater Table
- Production of Greenhouse Gases
- Production of Methyl-Mercury
- Negatively Impacted Biodiversity
- Lower Water Quality
The websites also mentioned the positive environmental impacts of reservoirs. Except that there aren’t really any… unless we’re talking exclusively about the human environment. Reservoirs and dams help control flooding — but flooding is a natural process actually required for the health of certain biological species.
Also, dams can produce hydropower, which again is helpful to the human environment but pretty much harmful to every other river-dependent life form.
What I was looking for in doing this research, however, was evidence of a reservoir that could enhance the “recreational” value of a river. For two decades, certain people have been promoting a reservoir two miles north of downtown Pagosa Springs on the Dry Gulch valley for the provision of drinking water. The Running Iron Ranch was purchased jointly by Pagosa Area Water and Sanitation District (PAWSD) and San Juan Water Conservancy District (SJWCD) in 2008, as the site for this future reservoir, and PAWSD customers have been paying off the $10 million loan ever since.
A recent ‘study’ by Lakewood-based Wilson Water Group (WWG), commissioned by SJWCD without any participation by PAWSD, argued that a reasonably large reservoir at Dry Gulch could enhance the “recreational and environmental demands” placed on the San Juan River during dry years.
There is plenty of evidence that artificial reservoirs can provide enjoyable boating, fishing and swimming activities — within the reservoir itself. We already have some of those activities available, at various local lakes and reservoirs.
But the WWG study seemed to be suggesting that a large reservoir at Dry Gulch could release water into the San Juan River at certain times of the years, and thereby noticeably improve the recreation in, and the environment of, the San Juan River.
The only evidence I found of ‘enhanced recreation’ resulting from reservoir water releases, relates to a rafting lottery on the Chama River, a 120-mile long tributary of the Rio Grande in New Mexico. Reportedly, water is released daily from the 197,000-acre-foot El Vado Reservoir to serve municipal Albuquerque, NM and the Middle Rio Grande Conservancy District, and the releases are timed during the middle of the day to accommodate boaters and tourists.
This water is available from the El Vado Reservoir, only because Archuleta County diverts up to 950 acre-feet of water per day through the San Juan-Chama Project diversion, to the reservoir.
From what I can tell from the 2021 ‘Economic Evaluation of Peak Flow Management on the Rio Chama’, the ‘recreational’ boating releases from El Vado Reservoir typically amount to about 600 CFS and happen on the weekends throughout the summer. The water flows through some Class III rapids, and then on to Alburquerque.
600 CFS is a minimum for enjoyable Rio Chama boat recreation, apparently. This program appears to have generated a $4 million rafting industry focused on the Rio Chama.
The largest possible reservoir in the Dry Gulch Valley — based on the current SJWCD water rights — is 11,000 acre-feet. About one-eighteenth the size of El Vado Reservoir. And without any “San Juan-Chama Project” filling it.
And without any Class III rapids downstream, as far as I know.
If a reservoir were built at Dry Gulch, and were somehow filled to 11,000 acre feet and it released 600 CFS for four hours per day during the summer months, it would be completely empty within 55 days.
This amateur calculation does not include the water lost to seepage and evaporation. Which would be considerable.
From an interesting 2017 article by Samantha Stahl on the Earth Law Center website:
The United States has 9,265 dams, second only to China which has a staggering 23,842. With climate change causing water shortages and storm surges, this might seem like good news. Dams store water, provide renewable energy and prevent floods. Unfortunately, they also worsen the impact of climate change. They release greenhouse gases, destroy carbon sinks in wetlands and oceans, deprive ecosystems of nutrients, destroy habitats, increase sea levels, waste water, and displace poor communities…
Our systematic overuse of fresh water, in addition to the already worsening effects of climate change, creates a need for artificial reserves…
…Dams would appear to conserve water by storing it, but the bigger picture shows this is not true…
On March 9 at 4pm, the PAWSD board of directors and the SJWCD board of directors — contractually bound to consider the construction of a future reservoir at Dry Gulch — will meet at the PAWSD offices to discuss points of agreement, and points of disagreement.
The public is invited to attend.