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In the mostly arid Southwestern United States, water availability (hydrology – a key fish habitat process), wildfires, and grazing intensity are important disturbances that are known to have major, negative effects on fish habitats. While this assessment indicated that many of the streams in this region are in good condition, a number of key habitat variables (i.e. water availability, wildlife frequency and intensity, and grazing intensity) could not be directly included in this assessment because national datasets of these disturbances and their measured variable are unavailable. Their absence from this assessment, along with absences of other disturbances, has likely produced an overestimation of habitat condition...
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The Lahontan Cutthroat Trout (Oncorhynchus clarki henshawi) is native to the Lahontan basin of northern Nevada, northeastern California, and southeastern Oregon. Like other native trout species, the Lahontan Cutthroat Trout is found in a wide variety of cold-water habitats including large terminal alkaline lakes, alpine lakes, slow meandering rivers, montane rivers, and small headwater tributary streams. They currently occupy only about 10 percent of their historic range primarily due to habitat fragmentation from dams and water diversions, changes in water flow patterns, loss of riparian and aquatic habitat quality, severe drought conditions, and the introduction of non-native trout species. One population in Walker...
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The Sonoran Desert is the only place in the world where Saguaro cacti grow. It can take up to 100 years for a Saguaro cactus to grow an arm in areas of low precipitation. The Sonoran Desert receives more rainfall than any other desert, which is approximately 10 inches (25 centimeters) a year on average. In the 1800s, many people used the Gila River as a trail across Arizona. This trail became known as the Gila Trail. Arizona is large enough to fit all of New England plus the State of Pennsylvania inside of it. Arizona is the only State besides Hawai'i that does not observe Daylight Savings time. Santa Fe, New Mexico, is the highest capital city in the United States at almost 7,200 feet (2,286 meters) above sea level....
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Map of the risk of current fish habitat degradation of inland streams of the Southwestern States.
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Partnership - Western Native Trout Initiative The Redband Trout, a group of Rainbow Trout, are remarkable fish. Some live as freshwater fish and some as anadromous fish that occupy both fresh and saltwater habitats during different stages of their lives. The interior Redband Trout is listed as a “Species of Conservation Concern” in most of its range. Its historic range covers eastern Washington and Oregon, northeastern California, central and southwestern Idaho, northwestern Montana, and parts of northern Nevada. Within this broad area, Redband Trout habitat can vary from higher elevation cold-water mountain streams to lower elevation warmer desert-type streams that have periods of low stream flows and high water...
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The Pahrump Poolfish (Empetrichthys latos) is an endangered endemic springfish and is the only remaining species in its genus, Empetrichthys. Originally occurring only in a large spring in southern Nevada, its entire historic habitat was lost in the 1960s due to excessive groundwater pumping, which desiccated the spring system. This species now exists in several refuge habitats in southern and central Nevada, as efforts to restore its original habitat have thus far been unsuccessful.
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The Woundfin (Plagopterus argentissimus) once ranged from southwest Utah to southern Arizona in the Colorado and Gila River basins, but now only occur in 12 percent of its historical range, and is classified as critically endangered. It prefers quiet water adjacent to riffles of swift, warm, turbid small to medium rivers, but spawns in swifter flowing water over gravel. Populations have been affected by habitat loss, fragmentation, and degradation caused by dams and water diversions. Woundfin populations have also shown declines in areas where the non-native Red Shiner has proliferated due to changes in water flow patterns caused by dams and diversions. The Red Shiner is both a predator of and a competitor with...
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Assessment Results for Rivers and Streams of the Southwestern States A. Pervasive disturbances: The most common disturbances based on total stream length in a given region. Top five overall most pervasive disturbances to all stream reaches, regardless of stream size and across all spatial scales (ranked highest first): Road crossing density Road length density Impervious surface Downstream dam density Population density Top three most pervasive disturbances to creeks (watersheds <100 km 2 in area) across all spatial scales: Road crossing density Road length density Impervious surface Top three most pervasive disturbances to rivers (watersheds >100 km 2 in area) across all spatial scales : Road crossing...
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The Desert Pupfish (Cyprinodon macularius) is a Federally listed endangered species found in shallow waters of rare desert springs, small streams, and marshes. The typical habitat includes clear water with aquatic plants or algae. These are difficult habitats for fish as they have high salinity water, high water temperatures, and low oxygen concentrations. Decline of the Desert Pupfish has been associated with dam construction, water diversions, groundwater pumping, pesticide drift, and encroachment of non-native vegetation such as Tamarix, also known as Salt Cedar. Salt Cedar can alter riparian habitats and the subsequent shading and roots can alter aquatic habitats.
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Water projects that include large dams and water withdrawal systems alter seasonal and daily water flows (hydrology) and water temperatures, adversely affecting desert species that are adapted to the natural cycles in this region. Combined with water diversions for domestic and agricultural use, drought conditions from 2010 to 2015 in the Southwest adversely affected all desert aquatic habitats. Large rivers in the Southwest states, such as the Colorado River and the Rio Grande, have been greatly affected by the construction of dams and diversions that: interfere with fish migration; alter in-stream habitat characteristics including sediment and woody debris movement; change water quality and temperature; reduce...
Partnership - Western Native Trout Initiative The Gila Trout ( Oncorhynchus gilae) is one of the rarest native trout species in the United States. Gila trout were listed as federally endangered in 1967, and re-classified as threatened in 2006 after efforts to restore populations were successful. Over the past 25 years, 14 wildfires have burned in watersheds occupied by Gila Trout, requiring fish evacuation on multiple occasions, and ten Gila Trout populations have been eliminated, setting back recovery efforts. While previous fires only affected one or two populations of fish, recent fires have become exceedingly large. The 2012 Whitewater-Baldy fire burned over 290,000 acres, encompassing much of the current...
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Agriculture is limited in the desert states but numerous hay fields, cotton and vegetable farms along the Colorado River near Parker, Arizona, and alfalfa and row crops in southwest of Reno, Nevada are located in areas estimated to pose high risk of fish habitat degradation. The agricultural areas of the desert states continue to demand more water from an over-allocated regional water supply. Farms dependent on irrigation and ever growing urban populations use increasing amounts of water diverted from streams and rivers, leaving less water for fish and other aquatic life and impairing connectivity of their habitats. Fragile and unique spring systems are drying up due to development of groundwater, as well as through...
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Partnership - Desert Fish Habitat Partnership The Muddy River is a major river in southern Nevada about 30 miles NE of Las Vegas. Many tourist destinations exist along and near the Muddy River, including: Moapa Valley National Wildlife Refuge and Warm Springs Natural Area at its headwaters; the towns of Moapa, Logandale, and Overton downstream; many scenic destinations such as Lake Mead National Recreation Area, Valley of Fire State Park; and several established and proposed wilderness areas. The Moapa Dace ( Moapa coriacea) is an endemic minnow occurring only in the upper Muddy River system. Requiring temperatures of at least 86° F for reproduction, the species is highly dependent on access to warm springs...
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Two rare trout subspecies, the Apache Trout (Oncorhynchus apache) and Gila Trout (Oncorhynchus gilae), are endemic to high elevation areas of Arizona and New Mexico. They are particularly threatened by hybridization with non-native trout and devastating wildfires. Severe wildfires caused by land use changes and exotic plants result in sedimentation and ash deposition in the clear waters where they live.
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The endangered Gila Chub (Gila intermedia) is found in springs and small streams of the upper Gila River basin mostly in southern Arizona but also in portions of Mexico. It prefers quiet, deep pools near cover, such as vegetation or boulders. The Gila Chub has been eliminated from 85 percent of its former range as a consequence of predation from introduced species and habitat loss resulting from water diversions, road crossings, livestock grazing, declining water quality, and groundwater pumping.
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Partnerships - Western Native Trout Initiative, Reservoir Fisheries Habitat Partnership, Desert Fish Habitat Partnership Funding was provided to construct three barriers to protect Rio Grande Cutthroat Trout populations in the Carson National Forest, New Mexico; one barrier to protect Gila Trout in Willow Creek, New Mexico; and one barrier to protect 54 miles of important Lahontan Cutthroat Trout habitat in Lower McDermitt Creek, Nevada, the largest meta population of Lahontan Cutthroat Trout in the Northwest population segment. Assessed 89 miles of streams for 15 fish populations and aquatic macroinvertebrate surveys, predominantly, to determine the effect of wildfires on Gila Trout and associated aquatic species...


    map background search result map search result map Summary of Scientific Findings for Southwestern States Description of Agriculture and Water Use as a Human Activity Affecting Fish Habitat in Southwestern States Southwestern States - Risk of Current Fish Habitat Degradation Map Habitat Trouble for Gila Chub in Southwestern States Habitat Trouble for Lahontan Cutthroat Trout in Southwestern States Fish Habitat Partnerships Making a Difference Muddy River, Nevada Fish Habitat Partnerships Making a Difference: Interior Redband Trout Range-wide Assessment Description of Dams and Other Barriers as a Human Activity Affecting Fish Habitat in Southwestern States Most Pervasive and Severe Disturbances for the Southwestern States Habitat Trouble for Pahrump Poolfish in Southwestern States Habitat Trouble for Apache Trout and Gila Trout in Southwestern States Habitat Trouble for Desert Pupfish in Southwestern States Habitat Trouble for Woundfin in Southwestern States Facts About Southwestern States Fish Habitat Partnership Activities for the Southwestern States Summary of Scientific Findings for Southwestern States Description of Agriculture and Water Use as a Human Activity Affecting Fish Habitat in Southwestern States Southwestern States - Risk of Current Fish Habitat Degradation Map Habitat Trouble for Gila Chub in Southwestern States Habitat Trouble for Lahontan Cutthroat Trout in Southwestern States Fish Habitat Partnerships Making a Difference Muddy River, Nevada Fish Habitat Partnerships Making a Difference: Interior Redband Trout Range-wide Assessment Description of Dams and Other Barriers as a Human Activity Affecting Fish Habitat in Southwestern States Most Pervasive and Severe Disturbances for the Southwestern States Habitat Trouble for Pahrump Poolfish in Southwestern States Habitat Trouble for Apache Trout and Gila Trout in Southwestern States Habitat Trouble for Desert Pupfish in Southwestern States Habitat Trouble for Woundfin in Southwestern States Facts About Southwestern States Fish Habitat Partnership Activities for the Southwestern States