Gila/Salt Intermediate Basins

The Salt River near Roosevelt is running at 308% of normal on September 27, 2026, reflecting heavy monsoon runoff from the eastern highlands. High streamflow in Salt and upper Gila tributaries supports riparian habitat and helps offset the region's chronic water deficits downstream.

Nine federally listed species have mapped ranges overlapping the Gila/Salt Intermediate Basins, including five Endangered species: California least tern, desert pupfish, Gila topminnow, Southwestern willow flycatcher, and Yuma Ridgway's rail. Two Threatened species and one Proposed Threatened species also occur here, though no designated critical habitat overlaps the area.

Mean daily high at Phoenix Airport was 103.6°F for the 30 days ending September 27, 2.1°F above the 1991-2020 normal of 101.5°F. Mean daily low was 83.8°F, 5.1°F above normal, marking an exceptionally warm late summer in the region.

Red Swamp Crayfish, an introduced species from the Gulf Coast, were documented September 12 in Phoenix. This invasive crayfish competes with and preys upon native aquatic species, including native crayfish and the larvae of pollution-sensitive insects.

Rush-desert-milkweed was observed with ripe fruits, recent fruit drop, and active fruiting on 2026-09-22. This native forb is dispersing seed as temperatures remain elevated.

Extreme drought (D3) covered 20.85% of Maricopa County in the week of 2026-09-22 to 2026-09-28, an increase from 0% coverage in the week of 2026-09-08 to 2026-09-14. This shift reflects worsening water stress as the ecosystem moves into fall.

The stream gauge on the Salt River at Priest Drive, near where the Verde River joins in below Scottsdale, read zero cubic feet per second on August 26. It's tempting to read that number as this summer's drought finally squeezing the last water out of the channel, and the numbers backing that read are real: Maricopa County is sitting at nearly 80 percent severe drought coverage, and Phoenix has been running more than five degrees above normal for daily highs. But the fuller explanation for a dry channel at this exact spot is infrastructure, not weather. This reach sits just below Granite Reef Diversion Dam, where the Salt River Project has for more than a century routed nearly all of the river's natural flow into the Arizona and South canals rather than leaving it in the bed. A USGS reconstruction of the system found this stretch running dry even in comparatively wet years back in the late 1970s. A zero reading at Priest Drive, in other words, is often the river doing exactly what it was engineered to do a hundred years ago; this year's drought and heat are simply added pressure on a channel that was already designed to run empty here most summers. A separate concern for this same stretch of the Gila/Salt Intermediate Basins is a permitted discharger rather than a diversion structure. MODERN INDUSTIES, INC holds a Clean Water Act discharge permit for this area, and its record is worth tracking precisely because the receiving channel is already this stressed. A waterway with no assured base flow has far less capacity to dilute or buffer any wastewater discharge than the same channel would in a normal year, so whatever this facility is permitted to release matters more here than it would somewhere with a reliable perennial flow underneath it.

Skunk Creek, near its confluence with the Agua Fria and Salt rivers, is running essentially dry. The USGS gauge there is reading close to zero cubic feet per second, with gage height under a foot and only one or two readings logged for the entire past week, a sign that flow has dropped so low it sits near the edge of what the instrument can reliably register. This did not happen overnight. Maricopa County spent ten straight weeks, from mid-May into late July, with 97 percent or more of the county locked in severe drought or worse. The past week is the first real crack in that stretch, with coverage easing to around 80 percent, still severe, but a meaningful drop in a single week. Skunk Creek's dry bed is what that ten-week siege looks like on the ground: an ephemeral desert wash that depends entirely on seasonal flow has simply run out of water to carry. It is worth being clear about what this is not. None of the nearby water bodies, including Skunk Creek, Cave Creek, the Arizona Canal, and Cortez Park Lake, are listed as impaired, and permitted dischargers upstream show no significant compliance failures. This is a drought story, not a pollution story. Groups such as the Arizona Land And Water Conservancy work on water and land conservation in this stretch of the valley, exactly the kind of low-flow, high-heat conditions where every bit of protected riparian buffer matters most for whatever wildlife is still finding water nearby.

The Sonoran Desert is paused right now in one of its rarest and most consequential moments: five species have simultaneously brought ripe fruit within a single week. Velvet mesquite pods are splitting, jojoba nuts are falling to the ground, California barrel cactus (Ferocactus cylindraceus) is dropping ripe fruit, buckhorn cholla (Cylindropuntia acanthocarpa) is releasing seeds, and saguaro (Carnegiea gigantea) has been fruiting continuously since mid-July. For animals that have just survived the bone-dry crucible of June — perhaps the harshest stretch of the desert year — this convergence is nothing less than a brief, brilliant pantry. The ecological logic behind this synchrony runs deep. Each of these species has independently evolved to front-load its seed dispersal just before the monsoon rains arrive, timing reproduction to the moment when seed-carrying animals are hungriest and germination conditions are about to become favorable. The result is a concentrated pulse of high-calorie food that functions almost like a scheduled event on the desert calendar — fat, sugar, and protein arriving all at once after months of scarcity. This window likely lasts only days to a couple of weeks before the rains shift the entire system into a new phase of insect emergence, green vegetation, and standing water. White-winged doves (Zenaida asiatica) are the most conspicuous participants in this abundance right now, observed calling, singing, feeding, and actively defending territory continuously through July 19. These doves have tracked the fate of saguaro stands in the Phoenix basin for over a century — their population dynamics are so tightly coupled to saguaro fruit availability that their numbers serve as a rough proxy for the health of the giant columnar cactus community. Historically, white-winged dove migrations were timed to saguaro fruiting with extraordinary precision; the industrial-scale loss of saguaro in lowland areas through the mid-twentieth century contributed to significant population declines before urban mesquite and other fruiting trees partially buffered the loss. The Tohono O'odham, whose homeland encompasses the core of the saguaro's range, recognized this exact convergence as the threshold of their new year. The saguaro fruit wine ceremony — the nawait I'itoi — was not simply a harvest ritual but a cosmological act: the fermented saguaro wine was understood to bring the rains, and the community's collective drinking was meant to mirror the way the earth itself would soon drink deeply. The simultaneous ripening of fruit across multiple species was the ecological signal that the monsoon was imminent and that a new seasonal cycle was beginning. This traditional ecological knowledge encoded what Western phenology is only now quantifying — that this multi-species fruiting window is a reliable, recurring inflection point in the annual calendar. When the rains do arrive in the coming days, the entire cast of characters here will shift almost overnight. Fallen seeds will germinate, ephemeral pools will fill, flying ant and termite colonies will erupt, and the animals currently focused on fruit will pivot to protein. The same doves calling over saguaro now will be feeding on insects and green seeds within a week. What is worth watching closely in the days immediately ahead is whether this year's monsoon onset is early, average, or late — because the gap between peak fruit availability and germinating rain determines how much of this seed crop survives to establish, and how much is consumed entirely by the animals holding vigil right now.

Thisbe's Tarantula-hawk Wasps (Pepsis thisbe) have been moving through the region in notable numbers over the past month — five sightings since mid-June, with three on a single day along Cave Creek early this month. These jewel-toned wasps are among the largest and most fearless hunters in the desert, and their females are after living tarantulas. Once found, a female paralyzes her prey with a potent sting and entombs the living spider in a sealed cell as provision for her emerging larva — a grim insurance policy timed to hatch as the heat peaks before the rains arrive. Tarantula-hawk presence in force carries old ecological weight. For generations, local naturalists have used their appearance as an informal calendar marker: when the wasps are out hunting in numbers, the monsoon is close. This year's sightings — including records ofMexican Tarantula-hawk Wasps and other hunting wasps — align with that forecast. The timing and intensity of this emergence suggest the pre-monsoon window is now.