Shale Deserts and Sedimentary Basins

In the span of two weeks, streamflow here surged from less than half a cubic foot per second — a channel barely alive — to 231 cubic feet per second, driven by summer monsoon pulses moving through the upper watershed. That kind of whipsaw hydrology is among the most ecologically disruptive sequences a high-desert stream can experience: it is not a gradual rise but a wall of energy that reorganizes the channel almost instantaneously. For a reach already carrying a burden of contamination, the timing could not be more consequential.During low-flow periods, fine sediments settle and contaminants concentrate in the shallow thalweg and streambed deposits — essentially pooling their toxicity in the one thin ribbon of water that aquatic life depends on. When the flood pulse arrives, all of that material mobilizes at once, flushing downstream in a single concentrated slug. Cottonwood Creek, which drains into this reach, carries an official federal impairment designation, and the conditions upstream have made that designation urgently relevant.The gravel pit operation known as Tri County Pit has exceeded its selenium discharge limits in each of the last four consecutive quarters, with the most recent exceedance running more than three times its permitted level. Four straight quarters of exceedance, with the most recent violation at over three times the permitted selenium concentration, directly upstream of a federally impaired waterway now experiencing its largest flow event in weeks. That convergence — chronic noncompliance meeting a high-magnitude flood pulse — is precisely when selenium loading to a downstream system becomes most dangerous.Selenium is insidious in aquatic systems because its toxic threshold sits just slightly above background concentrations, and it bioaccumulates through the food web with particular efficiency. Invertebrates absorb it from sediments; fish and waterbirds concentrate it further up the chain. The documented endpoint is reproductive failure: skeletal deformities in fish larvae, early embryo death in nesting waterbirds. Research following the Kesterson Reservoir disaster in California in the 1980s established the template — selenium at elevated but sub-lethal concentrations in adults produces catastrophic outcomes one generation later, and the damage is often not visible until breeding season reveals it.This corner of the Colorado Plateaus has always been shaped by the rhythm of monsoon pulses — the Ute and their predecessors understood these summer floods as agents of renewal, scouring channels, redistributing nutrients, and triggering spawning runs in native fish. In an unimpaired watershed, that reading holds. But when the channel carries a legacy of contamination from operations like those upstream, renewal and redistribution become the same event. What to watch for next: invertebrate communities in the weeks following this pulse, the behavior of any nesting waterbirds in the canyon corridor, and whether selenium monitoring data from downstream sampling points shows the spike this flood event would predict.

The river has fallen to a trickle — just 0.7 cubic feet per second today, down from nearly 270 cubic feet per second two weeks ago when snowmelt was at its height. Senior water rights are drawing the channel onto irrigated orchards upstream, leaving the stream channel nearly dry at peak irrigation season.What used to be a seasonal drought is becoming a pattern. Earlier springs mean snowmelt now peaks and depletes faster with each passing decade, leaving these hot, dry weeks longer and more intense. The stream temperature sits at 13.3°C, but as flow dwindles and air temperature climbs through July, the water will warm further — stressing the aquatic life that depends on this connectivity.The margin between ecological function and collapse narrows each time the cycle repeats. Fish, amphibians, and invertebrates that time their life cycles to historical flow patterns now face bottlenecks they didn't evolve to survive. The river is still running, but not running as itself.

A Northern Leopard Frog appeared in Cottonwood Creek on June 24th — a sighting worth documenting given how rare they have become on the west slope. These frogs are skin-breathers, highly sensitive to chemical and sediment contamination, and their presence signals something about water quality. Once common across this region, the species has retreated to fewer and fewer refuges.Yet the creek itself carries a federal impairment listing, and the situation is being actively made worse upstream. **The gravel pit operation ran 226% over its selenium permit limit in the first quarter of this year** — the fourth consecutive quarter it has violated its discharge limits. That leopard frogs have found their way back here, even briefly, is remarkable. Whether they can establish and persist depends now on whether the upstream contamination is brought under control.

Selenium contamination from the gravel pit operation has persisted through three consecutive quarters, with discharge reaching 335% of permitted limits. The selenium derives from local Cretaceous shale, a common geologic source in this region that mobilizes readily under disturbance. As summer flows drop — the channel now runs at 80 cubic feet per second, down from spring peak of 265 — whatever selenium reaches the water concentrates further downstream.The harm accumulates invisibly. Trout and waterfowl that feed in contaminated reaches show reproductive failure at concentrations too low to detect by eye or taste. Bioaccumulation means the heaviest burden falls on top predators and breeding females, whose eggs often fail to hatch or produce viable young. The creek has no visible algae die-off or discolored sediment; the real damage is in the tissues of fish and birds that no longer breed there as they once did.

The days near Paonia right now are as long as they get. Heat builds off the sagebrush flats by mid-morning, insects are everywhere, and if you look closely at a fence post, a rock face, or the broad leaf of a cottonwood, you may find a bold jumping spider looking back at you.Bold jumping spiders are compact, heavy-bodied hunters, black with white and sometimes iridescent green markings, and rarely longer than a thumbnail. What sets them apart is their eyes. The front-facing pair is enormous relative to their body, and the visual acuity those eyes provide is exceptional among spiders. They can resolve detail and judge distance with enough precision to stalk and pounce on prey from several body lengths away. Unlike web-building spiders, which wait for prey to come to them, bold jumping spiders actively move through their environment: pausing, pivoting, tracking. When a fly lands within range, the spider turns to face it directly, fixes it with those forward eyes, and creeps closer before launching. The jump is controlled and short, and the spider drags a silk safety line as it goes, so a miss does not mean a fall.This is peak season for them. Long days mean more insect activity across more hours, and the spiders track that activity. Around Paonia, they hunt across the sagebrush scrub and the drier rocky margins where insects concentrate on warm surfaces. Ten-lined June beetles are out now, large enough that a bold jumping spider would not attempt one, but the smaller flies, beetles, and moths that share this landscape are fair targets. The cottonwood stag beetle is similarly too large, but its presence signals the kind of decaying wood habitat that also shelters the small insects the spiders do take. Where the invasive broad-leaved sweet pea and purple crownvetch have established themselves along roadsides and disturbed margins, they draw in pollinators, and the spiders hunt at the edges of those patches too, taking whatever arrives. The spiders are not specialists. They take what they can catch.Breeding activity is running alongside all of this hunting. Male bold jumping spiders court females with a precise visual display: the male faces the female, raises and waves his front legs in a specific pattern, and moves side to side. The female watches. Her response determines whether courtship continues or ends abruptly. Vision is the medium of the whole interaction, which makes sense given how much of their lives depend on seeing accurately. Females lay eggs in a silk retreat, often tucked under bark or behind a loose stone, and guard them until they hatch. The young spiders that emerge this summer will spend the rest of the season hunting and growing, overwintering as subadults, and reaching maturity the following year.Other hunters share this landscape. Ash-throated flycatchers take insects on the wing from exposed perches. Western terrestrial garter snakes work the wetter margins. Blue-gray gnatcatchers pick small arthropods from leaf surfaces in much the same zones where jumping spiders patrol. The spiders are prey as well as predators. Birds take them when they can, and the spiders' habit of moving in open sight on sun-warmed surfaces makes them visible. Their response to a large moving shape is immediate: they turn to face it, drop to a lower surface, or hold still. That direct gaze, those big eyes tracking you, is the spider assessing whether to flee.If you are near any sun-exposed surface right now, a wooden railing, a stone wall, the rough bark of a cottonwood, take a slow look. The spider will likely see you before you see it, and it will already be watching.

Lewis's Woodpecker (Melanerpes lewis) returned to its cottonwood territory in June, holding the same stretch of riparian woodland where it was spotted in late May. The 25-day interval between sightings suggests the bird is establishing a foothold here — a significant sign given the species' steep decline across the western interior.This cottonwood corridor continues to anchor a remarkably intact riparian ecosystem. Over the past two months, observers have documented 105 bird and wildlife species in the immediate area, a diversity that speaks to the structural and botanical integrity of the forest. For a woodpecker already rare across much of its former range, the presence of mature cottonwoods with suitable foraging substrate and nesting cavities remains critical. As long as the riparian strip holds, there is reason to believe Lewis's Woodpeckers will return.

The air shimmers with heat across the sage flats near Paonia, where summer reaches its full intensity. Magpies call from scattered cottonwoods, and the scent of big sagebrush carries on what little breeze moves through the valley. If you are walking here, the sun presses against your shoulders with the weight of the longest days.A monarch butterfly moves through this landscape with purpose that seems impossible for something so fragile. Its orange wings catch the light as it searches, pausing at flower after flower, testing each one. The monarch is looking for something specific in this sea of blooms. Rocky Mountain thistle grows here in scattered patches, its purple flower heads rising above spiny stems. Both the butterfly and the plant share something beyond this moment: they are both threatened species, each rare in a landscape that once held many more of their kind.The thistle offers what the monarch needs most during breeding season. Its deep purple flowers produce nectar rich in the sugars that fuel long-distance flight and egg production. The monarch's proboscis unfurls to reach deep into the flower head, where dozens of tiny florets cluster together. Each floret holds its own small reservoir of nectar, and the butterfly works methodically from one to the next. While feeding, pollen grains stick to the monarch's legs and body, and when it moves to the next thistle, it carries genetic material between plants that may be separated by hundreds of yards.This exchange sustains both species through their most demanding season. The monarch female must find milkweed plants for egg-laying, but she also needs energy-rich nectar sources like thistle to fuel her search and support egg development. The Rocky Mountain thistle depends on pollinators like monarchs to move pollen between its scattered populations. In this fragmented landscape, where invasive cheatgrass and purple crownvetch compete for space, both species rely on finding each other across greater and greater distances. The thistle blooms through midsummer, timing its peak flowering with the monarch's breeding season, when the butterfly's need for nectar is highest.The monarch lifts from the thistle and continues its search, orange wings steady against the afternoon heat. Somewhere in the distance, a western kingbird calls from a fence post, and the sagebrush releases its sharp perfume into air that tastes of dust and summer. The thistle remains, purple against the pale earth, its flowers still heavy with nectar that catches the slanted light.

The mesas around Paonia hold the morning light differently now, filtered through leaves that have reached their full spring green. If you step outside, you might catch the sound that announces their return: a metallic trill that cuts through the air like a tiny bell being shaken at speed. The Broad-tailed Hummingbirds are back from their winter grounds, and the timing is no accident.These hummingbirds arrive when the landscape offers what they need most. The Sego Lily opens its three white petals in a perfect cup, each bloom lasting just a few days but appearing in sequence across the rocky slopes. The Scarlet Globemallow spreads its orange flowers in dense clusters, each one small but collectively offering a reliable nectar source that persists through the warming weeks. Evening primrose unfolds its pale yellow blooms as the day cools, extending the feeding hours into dusk. The hummingbirds move between these flowers with precision, their needle bills matching the depth of each corolla, their tongues extending to reach nectar at the base.A male Broad-tailed Hummingbird weighs less than a nickel, but he defends a territory that might span several acres. He positions himself where the flower density is highest, chasing away other hummingbirds with aggressive dives and that distinctive wing trill that serves as both warning and identification. His throat flashes magenta in the right light, a signal visible to rivals and potential mates alike. The females arrive shortly after, more quietly, focused on finding nest sites in the protection of scrub oak or pinyon pine. They build with spider silk and lichen, materials that expand as the eggs grow, creating a structure barely larger than a walnut that will hold two white eggs through the cool mountain nights.The relationship between hummingbird and flower runs deeper than simple feeding. The Sego Lily depends on these pollinators to transfer pollen between plants scattered across the mesa. The hummingbird's forehead picks up pollen as it feeds, carrying genetic material from flower to flower with each territorial patrol. Scarlet Globemallow has evolved specifically for this partnership: its orange color sits at the peak of hummingbird vision, and its flowers produce nectar throughout the day when the birds are most active. Even the evening primrose benefits, though it opens for night-flying moths. Hummingbirds feed on its early morning nectar, helping to pollinate flowers that might otherwise go unvisited in the brief window before they close.Listen for that metallic trill if you are walking the trails above Paonia this morning. The sound carries farther than you might expect, bouncing off the sandstone faces and echoing through the oak brush. Each trill marks a small territory claimed, a feeding route established, a breeding season begun. The flowers are open now, waiting in the warming air.