The San Juan Basin in northwestern New Mexico and southwestern Colorado is known for producing oodles of fossil fuels over the last century. But it is really so, so much more than that: An epicenter of cultures, lovely landscapes, and geological wonders. It is also a hotspot for fossils, some of which recently have yielded new information about the dinosaurs’ last days on earth.
While it’s generally accepted that non-avian dinosaurs were wiped out by an asteroid some 66 million years ago, researchers have long debated whether the big reptiles were doing well leading up to the cataclysmic event, or were already in decline and headed for extinction. A study published last month in Science, based on the fossil record of the San Juan Basin, finds that a diverse array of dinosaurs were actually flourishing at the end of the Cretaceous period. Had it not been for that asteroid, they might have stuck around for quite a bit longer.
And that’s not all for San Juan Basin dinosaur news! In September, a team of researchers announced they had identified a new species of duck-billed dinosaur in northwestern New Mexico. The Ahshiselsaurus, an herbivore, weighed up to nine tons and spanned up to 35 feet from bill to tail.
In a news release, the New Mexico Department of Cultural Affairs notes that the bones that led to the identification were unearthed in 1916 in what is now the Ah-shi-sle-pah Wilderness in San Juan County. “In 1935, the fossils were classified as belonging to another hadrosaurid called Kritosaurus navajovius. However, this new research identified distinctions between these fossils and all known hadrosaurids, including several key differences in the animal’s skull.”
Cottonwood trees in full autumn splendor in the Paradox Valley, Colorado. Jonathan P. Thompson photo.
🥵 Aridification Watch 🐫
This past weekend, my sister held the annual garlic-planting and apple cider-making ritual at her farm in the North Fork Valley in western Colorado. Folks from all around gather to help put thousands of garlic cloves into the ground. At the same time, a handful of us crank the handle and toss apples into the 125-year-old cider press that my ancestors brought to the Animas Valley from Pennsylvania in the early part of the century.
It was a lovely day, with an intensely blue, cloudless sky and high temperatures in the 60s. We felt lucky to have such conditions in early November, but they weren’t wildly abnormal. Though a few places in the region set daily high temperature records, at least as many also set daily low temperature records as the mercury dipped down to around 22° F, even in the lowlands, overnight.
More striking to me was when I stopped in Silverton on the trip back to Durango to take a bike ride on the new trails on Boulder Mountain. That mountain biking is even an option in Silverton in early November is a little odd. That the trails were bone dry at 10,600 feet in elevation is even odder. And that I was not just warm, but downright hot and sweaty in just short sleeves and shorts felt downright weird.
A cursory look at the data reveals that this has been one of the wettest — and least snowiest — starts to a water year on record, at least in southwestern Colorado. The huge, flood-spawning rains of October pushed the accumulated precipitation levels up into record high territory. But most of that liquid abundance fell as rain, not snow, even at high elevations. And the warm temperatures that followed has deteriorated what little snowpack existed. It’s striking to see only a thin layer of white painting its designs on north-facing slopes at 12,000 or 13,000 feet. And without a radical shift in weather (which is certainly possible), it’s hard to imagine ski areas opening by Thanksgiving.
Still, we’re only about one month into the 2026 Water Year, so it’s far too early to draw any conclusions from the data. Last year started out as one of the snowier seasons on record, before fading out into a pretty sparse snow year.
North-facing peaks in the San Juan Mountains, late October 2025. There’s snow, but a lot less than one would expect. Jonathan P. Thompson photo.
📖 Reading Room 🧐
Nick Bowlin and ProPublica just published an extensive investigation into oil and gas field “purges,” which is when injecting produced wastewater underground forces toxic water to spew out of old wells in mind-blowing volumes, killing vegetation and trees and contaminating the earth.| Bowlin’s investigation focuses on Oklahoma — where regulators are doing little to address it — but these purges occur anywhere that produced wastewater is injected into the ground as a way to dispose of it, which is to say every oil and gas field from Wyoming to New Mexico. Each barrel of oil pulled from the ground is accompanied by anywhere from three to 30 barrels of brackish wastewater that can be contaminated with an assorted soup of hazardous chemicals. This means that hundreds of billions of this stuff must be disposed of each year, usually by deep injection. As oil production continues, and as more and more wells are “orphaned” or abandoned without being plugged, the purge problem will only grow worse.
KUNC’s Alex Hagar has a nice, good-news piece on how beavers are returning to Glen Canyon and its tributary canyons as Lake Powell’s water levels recede. It’s yet more evidence that if — when — Lake Powell disappears, the canyons it and ecosystems it drowned will eventually recover, and may do so far more quickly than might be expected.
🔋Notes from the Energy Transition 🔌
Those of you who watch Denver television will certainly recognize longtime Denver 7 weather forecaster. He retired a little while back and has taken on a sort of second career advocating for a Super Grid — an integrated, nationwide, direct current, underground power grid designed to move power from where it’s generated to where it’s needed when it’s needed.
It’s a cool idea, but also a very, very ambitious one. Instead of rehashing all of the details, I’ll let you watch this video of his presentation, which gives a very informative overview of the whole energy situation.
Colorado is in its first year of responding to a zebra mussel infestation in a big river, the Colorado River. State staff say they have what they need to handle the high-priority needs — they just need their funding to stay off the chopping block.
The fast-reproducing mussels, or their microscopic stage called veligers, were first detected in Colorado in 2022. Since then, the state’s aquatic nuisance species team and its partners have been working to monitor water, decontaminate boats, and educate the public to keep the mussels from spreading. That effort logged a serious failure this summer when state staff detected adult zebra mussels in the Colorado River, where treatment options are limited.
CPW sampling on the Colorado River found zebra mussel veligers. The river is now considered “positive” for zebra mussels from its confluence with the Roaring Fork River to the Utah state line. CREDIT: PHOTO COURTESY OF COLORADO PARKS & WILDLIFE
“We’re continuing to sample the Colorado from below the Granby Dam all the way out to the [Utah-Colorado] state line,” said Robert Walters, who manages the invasive species program for Colorado Parks and Wildlife.
Adult zebra mussels, about the size of a thumbnail with a zebra-striped shell, reproduce quickly and can clog up pipes, valves and parts of dams, costing millions of dollars to remove. They also suck up nutrients, out-eating other native aquatic species, and their razor sharp shells cause headaches for beachgoers.
The state’s first adult zebra mussel showed up in Highline Reservoir near Grand Junction in 2022. But even after the lake was drained and treated, the mussels appeared again.
Colorado has been working to keep these invasive species out of its waters since 2007, when a task force was created to coordinate management efforts.
In 2008, Colorado approved a law that makes it illegal to possess, import, export, transport, release or cause an aquatic nuisance species to be released.
Now, the program completes over 450,000 inspections each year, according to Colorado Parks and Wildlife’s website. The teams have intercepted 281 boats with zebra or quagga mussels attached.
But their treatment options are limited on the Colorado River. CPW does not intend to treat the main stem of the Colorado River due to multiple factors, including risk to native fish populations and critical habitat, the length of the potential treatment area and complex canal systems, the agency said in a mid-September news release.
The goal continues to be educating the public — including lawmakers who are scheduled to hear an update on the zebra mussel issue during the Oct. 29 Water Resources and Agriculture Review Committee meeting.
“What I think that we really need to help us more effectively tackle this issue is a higher level of public awareness,” Walters said.
The first year of infestations
For invasive species teams, the first year involves a lot of monitoring, according to Heidi McMaster, the invasive species coordinator for the U.S. Bureau of Reclamation.
Quagga mussels were discovered in Lake Mead, Lake Mojave and Lake Havasu on the Colorado River in January 2007. The mussels were later confirmed in Lake Powell in 2013, according to the Bureau of Reclamation.
Hoover Dam with Lake Mead in the background December 3, 2024.
Colorado River water from Colorado’s mountains eventually collects in Lake Powell before flowing through the Grand Canyon to downstream states, Lake Mead and Mexico.
“I would think that the first response is probably panic, especially if people are not prepared for it,” McMaster said. “Once that initial panic wears off, it is tapping into the existing resources, the preparedness plans that state or managers have on how to deal with it.”
During the first year, specialists are looking at existing rapid response plans, vulnerability assessments and communication plans. They take samples and track life cycles to try to understand how the mussels reproduce, how environmental conditions impact breeding and what kinds of treatments might work to stop the spread.
In the Southwest and along the Colorado River, the temperature of the water allows invasive species to breed multiple times a year, McMaster said. Each one can produce a million larvae. Not all survive: There are turbulent waters, areas with fewer nutrients, and other threats, like predators. But if they grow to adulthood they can layer on top of each other on underwater surfaces.
If left unchecked, invasive mussels could clog up pipelines that carry cooling water to turbines used to generate hydroelectric power. Without the cooling effect of the water, the turbine would “burn up” and power generation would shut down, McMaster said.
The goal at the end of the first year is mainly to inform the public. That means repeating the “clean, drain, dry” refrain as often as possible to anyone moving watercraft from one body of water to another, she said.
After that, a successful first-year response will also include setting up inspection and decontamination stations. Then, specialists move onto treatment options, McMaster said.
At Hoover Dam and Lake Mead, on the Nevada-Arizona border, managers took an aggressive treatment approach to avoid damage to the dam, she said. They used UV lights to stun and temporarily paralyze the microscopic veligers so they cannot attach inside the dam.
“Prevention is still the No. 1 goal,” McMaster said.
It’s the cheapest and least risky option, she said. Once an invasive mussel species arrives in an area, however, the costs can ramp up exponentially into the millions of taxpayer dollars. The goal is always to keep them at bay as much as possible, she said.
“They might be in the state of Colorado,” McMaster said, “but if you look at the overall percentage of uninfested areas, that’s still a lot of maintenance that’s not having to happen.”
Pest control on a private lake
On July 3, Colorado Parks and Wildlife staff discovered adult zebra mussels in a privately owned lake in western Eagle County, according to a news release.
CPW also identified additional zebra mussel veligers in the Colorado River near New Castle, Highline Lake and Mack Mesa Lake at Highline Lake State Park, the release said.
There were too many mussels in the Eagle County lake to count, Walters said in late August. Any hard structure in the lake and any underwater rocks were relatively covered in adult mussels, he said.
An invasive species specialist said in July that they believed the lake was an upstream source of the mussels in the Colorado River, and that an outlet from the lake was bringing zebra-mussel-infested water into the Colorado River, according to news reports.
Walters said that has not been confirmed.
“We are just continuing to try to monitor,” Walters said during an interview Aug. 29. “What I can say is that, to the best of our knowledge, there currently is no connection from this privately owned body of water into any of the river systems of the state.”
The state’s team spent about eight hours on Aug. 25 treating the lake with a copper-based molluscicide, a substance used to kill mollusks, he said.
Staff also sampled the private lake’s water Aug. 27 to make sure the treatment’s concentration was at the right level and planned to continue monitoring and treating the water throughout September, Walters said.
No boats or other watercraft were entering or exiting the lake, he said.
“It’ll be a long time before we know if it was truly effective at eradicating the zebra mussels,” he said.
Zebra mussels. Photo credit: Colorado Parks & Wildlife
The state focuses its monitoring efforts on public waters, mainly those with high recreational use. Motorboats and other types of boats are the main way the mussels spread, he said.
However, that doesn’t mean the teams don’t survey private ponds and lakes, Walters said.
After the state discovered zebra mussel veligers in the Colorado River and Grand Junction area, they started asking landowners if they could survey private lakes, ponds, gravel pits and more near the river. They often survey privately owned recreational areas, like water skiing clubs, he said.
“We have been trying to work with those private landowners to allow us access to come out and sample them for invasive species,” Walters said.
We need to keep our existing funding
But with thousands of private and public water bodies in the state, CPW alone is never going to be able to monitor all of them as frequently as the high-risk water bodies, he said.
The staff normally work in teams of two to inspect reservoirs and lakes. They pull fine mesh nets through the water to try to find microscopic veligers. They do shoreline surveys to look for razor sharp shells and other signs of invasive species.
On a small pond, the process can take one to two hours. On a big reservoir like Blue Mesa, Colorado’s largest reservoir, it would take six to eight hours, he said.
“I don’t think that there is ever going to be capacity to monitor every public and private body of water in the state of Colorado. And I don’t think that that’s ever going to be our expectation,” Walters said.
The aquatic nuisance species program has more resources than ever, but there’s always room for more, Walters said.
“At this time, we feel like we do have a good amount of resources to be able to sample the waters that we consider to be the highest priority,” he said.
Formerly, the team was based in Denver. Now, the state has established a traveling team to cover the Western Slope and another focused on the Grand Junction area.
They don’t need more authority to monitor private water bodies, he said.
“What we need is to continue to receive the funding that we are receiving today, and hope that does not get threatened if there’s any sort of budget cuts that are considered,” Walters said.
Aquatic nuisance species stamp sales cover about $2.4 million, or 50%, of the program’s annual funding needs. All motorboats and sailboats must have this stamp before launching in state waters, according to the CPW website.
Colorado state law calls on federal agencies, like the Bureau of Reclamation and U.S. Forest Service, to cover the other half of the funding needs since many high-risk waters in Colorado are federally owned or managed.
How are other water providers responding?
Zebra mussels go with the flow. They naturally move downstream with the river’s current, but boats traveling from one lake to another can carry them upstream.
That has upstream water managers, like Northern Water and Denver Water, keeping a close eye on developments along the Colorado River.
The Northern Colorado Water Conservancy District works with the federal government to transfer Colorado River water on the Western Slope through a series of reservoirs, pump stations and tunnels — called the Colorado-Big Thompson Project — to farmland and over 1 million residents from Fort Collins across northeastern Colorado.
Horsetooth Reservoir looking west from Soldier Dam. Photo credit: Norther Water.
Zebra mussels are such prolific reproducers they can clog up water delivery pipelines, the main concern for a water manager like Northern Water, spokesman Jeff Stahla said.
The C-BT project is no stranger to invasive species. In 2008, quagga mussels showed up in several reservoirs, including Grand Lake, Lake Granby and Shadow Mountain Reservoir. Another reservoir, Green Mountain, was also positive for quagga mussels in 2017.
All of the lakes are mussel-free and delisted, Stahla said. Now they’re tightening up security.
“The biggest task we can right now is to inspect those boats going into the reservoirs to make sure that they’re not going to be causing the problem,” he said.
Dillon Reservoir in Summit County is Denver Water’s largest reservoir. Photo credit: Denver Water.
Denver Water, which serves 1.5 million people in Denver and nearby suburbs, is also focused on inspecting and decontaminating boats.
“It’s a little unnerving. That’s for sure,” Brandon Ransom, recreation manager for Denver Water, said. “It’s certainly not welcome news that anybody in the state wants to see.”
The water provider also transfers Colorado River water through mountain tunnels and ditches to Front Range communities. Not only are the invasive mussels a concern for gates, valves, pipes and tunnels, they also cause problems for recreation. The shells are sharp enough to cut feet and the decaying mussels and old shells “smell to all heck,” Ransom said.
They haven’t launched new prevention efforts in response to zebra mussels reports, but that’s because the provider and its partner agencies already had fairly controlled boat launch and inspection procedures, he said.
A view of part of Eleven Mile State Park in Park County, Colorado. The view shows the Eleven Mile Canyon Dam and part of the Eleven Mile Canyon Reservoir. By Jeffrey Beall – Own work, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=154086653
They already intercepted adult zebra mussels on boats this year, he said. The latest catch was at Eleven Mile Reservoir in early October.
They’re trying to get the word out to people to make sure their boats and gear are clean, drained and dry. The zebra mussels like to hide in dark cavities, particularly around motors.
The good news is that Denver Water’s reservoirs, pipelines and tunnels on the Western Slope are upstream from the main infested areas, Ransom said.
“It doesn’t help me sleep at night, let’s put it that way,” he said. “We know that it’s closer and closer, and we’re trying to be extra vigilant when it comes to prevention in our waters.”
