Pittman Wash’s headwaters are on Black Mountain, south of Henderson, Nevada, with the main channel flowing into the Las Vegas Wash near the Las Vegas Wetlands Park. Pittman Wash has a highly variable urbanized history, ranging from a concrete channel and culverts in much of its extent, to a vegetated channel in its reach particular between Pecos Road and Arroyo Grande Boulevard. The channel is designated and maintained for flood control flows, has a sanitary sewer line in the channel bed, has installed erosion control features, and is used by the public as a recreational feature. The channel has also become an important resource for wildlife and native riparian vegetation, especially since the flow of water became perennial.
Water is the driving force in the natural history of Pittman Wash. The Wash has a permanent, relatively low flow except during and after rainfall events when runoff from the streets and other impervious surfaces contributes to a considerable flow. Flows can be described as “flashy” with a low flow much of the time, but high flows can appear within minutes, and dissipating back to low flow almost as fast. Where the wash has gravels and sands, much of the water flows subsurface, and is not visible on the surface. The mostly subsurface bedrock layer (a caliche rock) restricts the water from infiltrating into the deeper ground water aquifer, allowing for the surface or residual pools and flows being confined at or near the surface. Residual pools along Pittman Wash provide valuable water to wildlife
The water quality in the Wash is moderate, but is mostly contaminated after rainfall events, due to runoff from streets and lawns contributing oils and greases (from streets and driveways), pet wastes, fertilizers, and other contaminates (from lawns and other impervious surfaces). Also, after storms, the runoff carries everything from paper to shopping carts into the Wash. While contaminates enter the water, there are natural functions associated with streams which alleviate the contaminates. Riffles on the stream surface and flowing water allows for both oxygen to be absorbed into the water and for carbon dioxide to be released from the water. Oxygen in turn promotes the growth of beneficial bacteria and fungi, which breaks down the pollutants. Nitrates and phosphates from pet wastes and fertilizers are taken up by the plants, a process called biofiltration, allowing for the rapid growth in the vegetation which you see along the Wash. Algal growth likely oxygenates the water during its active growth in the spring, through photosynthesis, but becomes a carbon dioxide source as the algal growth ages and turns yellow or brown during the summer. The quantity of oxygen provided to the water during the early growth stage is approximately equal to the carbon dioxide given off as the algal mat begins to decay.
The bed of Pittman Wash is mostly composed of silts (fine particles), sands, gravels, larger stones, and boulders. These sediments typically allow water movement through the substrates, but also allow for quick drying when the water level drops.
Pittman Wash, between Pecos Road and Arroyo Grande Boulevard is a perennial flowing, highly urbanized, with a good diversity of native and some introduced plant and animal species, much of which is characteristic of Mojave Desert riparian ecosystems.
Pittman Wash between Green Valley Parkway and Valle Verde Drive is an excellent example of a desert drainage channel created by repeated (even if irregularly occurring) storm-generated flows from higher elevations in the Black Mountains toward Lake Mead. The channel’s width and depth, as well as the relatively large size of the rocks being moved along the wash, attest to the high energy flows in the Wash.
The plants and animals of Pittman Wash are typical of the desert/urban interface, having typical Mojave Desert species mixed with those species which either benefit from being near people, or which have been introduced into the area.
TREES
California Fan Palm (Washingtonia filifera)+
Catclaw Acacia (Senegalia greggii)
Desert Willow (Chilopsis linearis)
Goodding’ Willow (Salix gooddingii)
Honey Mesquite (Prosopis glandulosa)
Mexican Fan Palm (Washingtonia robusta)+
Fremont Cottonwood (Populus fremontii)*
Palo Verde (Parkinsonia sp.)+
Screwbean Mesquite (Proposis pubscens)*
Tamarix (Tamarix ramosissima)+
SHRUBS
African Sumac (Rhus lancea)
Chaste Tree (Vitex agnus-castus)+
Cheesebush (Ambrosia salsola)
Creosote Bush (Larrea tridentata)
Desert Broom (Baccharis sarothoides)
Desert Saltbush (Atriplex polycarpa)
Desert Trumpet (Eriogonum inflatum)
Desert/Globe Mallow (Sphaeralcea ambigus)
Mormon Tea or Joint-fir (Ephedra nevadensis)
Oleander (Nerium oleander)+
Pima Ratany (Krameria erecta)
Quailbrush (Atriplex lentiformis)
Rubber Rabbitbrush (Ericameria nauseosa)
Sacred Datura or Trumpet flower (Datura wrightii)
White Bursage (Ambrosia dumosa)
CACTI
Beavertail (Opuntia basilaris)
Pencil Cholla (Cylindropuntia ramosissima)
Silver Cholla (Opuntia polyacantha var. echinocarpa)
GRASSES
Mexican Sprangletop (Leptochloa fusca ssp. uninervia)
Fountain Grass (Pennisetum setaceum)+
Hare’s foot Grass (Polypogon monspeliensis)+
Bermuda Grass (Cynodon dactylon)+
UPLAND PLANTS
Barbwire Russian Thistle (Salsola paulsenii)+
Prickly Sow-Thistle (Sonchus asper)
Tansy Mustard (Descurainia sophia) -
Small yellow Sweetclover (Melilotus indicus)+
White Clover (Trifolium repens)+. –
AQUATIC AND RIPARIAN PLANTS
Common Cattail (Typha latifolia)
Hardstem Bullrush (Schoenoplectus acutus)
Dock (Rumex sp.)
Narrow-leaf Cattail (Typha domingensis)
Sweet-scented Fleabane (Pluchea odorata)
Spanish false Fleabane (Pulicaria palidosa)+
Three Square (Schoenoplectus americanus)
Water Speedwell (Veronica anagallis-aquatica)+
MAMMALS
Coyote (Canis latrans)
Desert Cottontail Rabbit (Sylvilagus audubonii)
White-tailed antelope squirrel (Ammospermophilus leucturus)
Desert Woodrat (Neotoma lepida)
BIRDS
Mallard (Anas platyrhynchos)
Gambel's Quail (Callipepla gambelii)
Snowy Egret (Egretta thula)
Turkey Vulture (Cathartes aura)
Cooper's Hawk (Accipiter cooperii)
Red-tailed Hawk (Buteo jamaicensis)
Killdeer (Charadrius vociferous)
Lesser Yellowlegs (Tringa flavipes)
Rock Pigeon (Columba livia)+
Mourning Dove (Zenaida macroura)
White-winged Dove (Zenaida asiatica)
Inca Dove (Columbina inca)
Greater Roadrunner (Geococcyx californianus)
Lesser Nighthawk (Chordeiles acutipennis)
Anna’s Hummingbird (Calypte anna)
Costa’s Hummingbird (Calypte costae)
Northern Flicker (Colaptes auratus)
Western Kingbird (Tyrannus verticalis)
Lesser Goldfinch (Spinus psaltria)
American Crow (Corvus brachyrhynchos)
Verdin (Auriparus flaviceps)
Northern Mockingbird (Mimus polyglottos)
Phainopepla (Phainopepla nitens)
Abert's Towhee (Melozone aberti)
Great-tailed Grackle Quiscalus mexicanus)
House Finch (Haemorhous mexicanus)
House Sparrow (Passer domesticus)
REPTILES
Zebra-tailed Lizard (Callisaurus draconoides)
Desert spiny Lizard (Sceloporus magister)
Side-blotched Lizard (Uta stansburiana)
Desert night Lizard (Xantusia vigilis)
Western whiptail Lizard (Aspidosceles tigris)
Red Racer (Masticophis flagellum)
ARACHNIDS (SPIDERS AND KIN)
Arizona bark Scorpion (Centruroides exilicauda)+
Yellow ground Scorpion (Paravaejovis confuses)
Black widow Spider (Lactrodectus hesperus)
Desert recluse Spider (Loxosceles deserta)
Nevada Tarantula (Aphonopelma iodius)
Normal flows in Pittman Wash, flowing over impervious caliche bedrock.
Normal flow in Pittman Wash, flowing through sands, rocks, and gravels. Occasionally the channel widens, creating pools. Much of the runoff in areas such as this are subsurface, through the substrate.
Flows in Pittman Wash can change rapidly during and after rainfall in the watershed. These flows can move sand and rocks, as well as other debris from upstream.
There are a number of Fremont Cottonwoods in the Wash, especially just to the south of the Silver Springs Recreation Center. These are the tallest trees in the Wash and are typical trees in desert washes. In the fall, the leaves turn yellow to gold colors before shedding their leaves for the winter.
Many people don't realize that all trees have flowers, because frequently the flowers are green and not particularly showy. Fremont cottonwoods fall into this category, with flowers appearing as the leaves are just budding/opening. The flowers hang down from the twigs in arrangements called catkins.
Catclaw Acacia can be identified by its small compound leaves, and its curved prickles (prickles are outgrowths of the bark on a twig), which resemble the claws of a cat, and catch onto anyone who gets too close when walking by the trees. The flowers are also arranged in catkins, appearing in April or May.
Mesquite trees are about the same size as the catclaw acacias, but are easily identified by having straight spines (spines are modified leaves). Screwbean mesquite also has yellowish catkins and produces seed pods which are segmented similar to the rattle on the tail of a rattlesnake. The seed pods are an important food source for many birds and mammals.
Honey Mesquite in another small tree, differing from screwbean mesquite by having less densely crowded leaflets and with seed pods which are flattened and more like pea pods. This tree is also important as a food for willife.
Desert Willow is not a true willow, but belongs to a plant family characterized by large, colorful flowers. These trees are adapted to grow along stream corridors, however they have been cultivated and adapted to have more diverse flower colors, and to grow in areas with some irrigation to support their growth and survival. The flowers last from late spring into the hot desert summers.
Sacred Datura is a common plant in moist soils throughout the southwestern U.S., with large white flowers during the late spring and summer.
One of the characteristic plants of the Mojave Desert is creosote bush, a mid-sized shrub with dark green leaves and yellow flowers. These shrubs can live for hundreds or thousands of years, but those found in the Wash are all less than 20 years old. Thes plants produce substance which limits growth of other plants nearby, thus limiting competition for water and nutrients.
Fall colors in the Wash are enhanced by the flowers of rubber rabbitbush, which can be covered in these bright yellow clusters of flowers.
A common bird seen, but more often heard in the Wash is the killdear, so named because of its call when distrubed. Killdeers can be found year round in the Wash, but nest during the spring, laying eggs directly on the gravel, with the eggs colored similar to the gravel.
The Wash is home to many species of dragonflies, such as this Flame Skimmer. Dragonflies lay their eggs in the water and hatch out as aquatic larvae, generally found under rocks, where they are predators on other aquatic insects. When ready, they crawl up on plant stems, shed they exoskeleton, and emerge as one of the fastest flying insects. Dragonflies eat other small flying insects, including mosquitos. Interesting, dragoflies are one of only a few insects which can turn their head to look around.
If you see a snake in the Wash it is most likely a Red Racer. Red Racers are one of the few snakes out in the middle of hot days. This snake is a subspecies of the Coachwhip snake of the eastern U.S. These fast-moving snakes are not venomous and will try to escape if approached but will bite if you try to grab ahold of one.
Check out this great video
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