Proceedings of the Hydrology section of the Annual Meeting of the Arizona-Nevada Academy of Science. Full text manuscripts of work presented. Research related to water resources, water management, and hydrologic studies primarily focused regionally on southwestern US.

Digital access to Hydrology and Water Resources in Arizona and the Southwest has been made possible by a collaboration between the Arizona-Nevada Academy of Science and the University of Arizona Libraries.

The collection consists of current and back issues from Volume 1 (1971) - Volume 42 (2012). The content is available both as complete issues, and as individual articles. Content is available open access.

There will be no 2013 Proceedings due to a joint meeting with AAAS-Pacific Division in 2013, with no separate Hydrology section. Publication will resume with 2014.


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    Ffolliott, Peter F.; Brooks, Kenneth N.; Neary, Daniel G.; Univ Arizona; Univ Minnesota; USDA Forest Service, Rocky Mountain Research Station (Arizona-Nevada Academy of Science, 2014-04-12)
    Water harvesting, also called rainwater harvesting, is a technique of developing surface water resources to augment the quantity and quality of water available to the people in arid and semi-arid regions where other water sources are not readily available or too costly to develop and use. A waterharvesting system consists of facilities for collecting and storing rainfall and the resulting surface runoff until the water is used for livestock, small-scale agricultural production, or domestic uses. A distribution facility can also be required unless the collected water is immediately concentrated in the soil profile to grow plants. For example, a distribution facility is needed when the stored water is used to irrigate an agricultural crop or provide water to households.Water harvesting is potentially applicable in almost any area receiving at least 100 millimeters (mm) of annual rainfall (National Academy of Science 1974). Larger volumes of water can be stored on sites where the annual rainfall is 250 mm or more and an adequate storage facility is available.

    Gottfried, Gerald J.; Ffolliott, Peter F.; Neary, Daniel G.; Decker, Donald D.; U.S. Forest Service; Univ Arizona; USDA Natural Resources Conservation Service (Arizona-Nevada Academy of Science, 2014-04-12)
    The Southwestern Borderlands Region of Arizona, New Mexico, and northern Mexico are known for its biological diversity and beauty. The area is characterized by its mountains surrounded by deserts and grasslands. The region contains representative animals and plants from the Rocky Mountains in the north to the Sierra Madre Mountains to the south. Madrean oak woodlands and savannas are common within the area covering millions of acres. Periodic fires caused by lightning or Native American people maintained the grasslands and reduced the encroachment of woody vegetation and the accumulations of woody fuels. However, the role of fire declined after the transcontinental railroad was completed and large herds of cattle were introduced into the area. Fires are still ignited but do not spread throughout the landscape largely because overgrazing caused a decline in herbaceous vegetation which carried fires. Aggressive fire suppression by land managers also contributed to the reduced influence of fire. Public and private land managers are concerned that the lack of fires in the Borderlands Region is to blame for the increase in woody species and the decline in biological diversity and productivity of the grasslands and savannas. The Peloncillo Programmatic Fire Plan was developed by the Coronado National Forest to re-introduce landscape level prescribed and managed fires into Forest Service and Bureau of Land Management lands within the Peloncillo Mountains (Gottfried et al. 2009). One of the issues was whether it was best to burn in the cool-season (November-April) or the warm-season (May-October) because of concerns about potential harm to the threatened New Mexican ridge-nosed rattlesnake (Crotalus willardi obscurus) and the endangered Palmer agave (Agave palmeri). The agave is important because it provides food for the endangered lesser long-nosed bat (Leptonyceris curasoae). The area usually burns during the warm period prior to the monsoon season.

    Gottfried, Gerald J.; Ffolliott, Peter F.; Neary, Daniel G.; U.S. Forest Service; Univ Arizona (Arizona-Nevada Academy of Science, 2014-04-12)
    Silvicultural studies on the Fort Valley Experimental Forest, the oldest experimental forest in the United States, have been the basis for planning and implementing watershed management experiments in ponderosa pine (Pinus ponderosa) forests. The primary purpose of these experiments had been to evaluate the potentials for increasing streamflow volumes while maintaining or improving other ecosystem-based, multiple-resource values. Knowledge gained from these experiments has provided today's managers with a better appreciation of the past management of Arizona's ponderosa pine forests. The effects of applying silvicultural treatments formulated largely from studies on the Fort Valley Experimental Forest and effects of these treatments on forest structures are reviewed in a historical context in this paper.

    Gottfried, Gerald J.; Ffolliott, Peter F.; Neary, Daniel G.; Rocky Mountain Research Station, U.S. Forest Service; Univ Arizona, Sch Nat Resources & Environm (Arizona-Nevada Academy of Science, 2014-04-12)
    The 2.4 million acres of ponderosa pine (Pinus ponderosa) forests and the many resources that they provide are the basis for the wide range of interests and concerns relative to their stewardship by management agencies, special interest groups, and the general public. As might be expected, therefore, there are conflicts of interest among stakeholders. These conflicts often concern the impacts of tree cutting activities on non-market benefits such as wildlife habitats, streamflow regimes, and scenic beauty. A recent issue of conflict has been the application of prescribed or managed fires to reduce the large accumulations of flammable fuels that can cause damaging wildfires when ignited - especially ignitions in the wildland-urban-interface. However, silvicultural practices such as the application of prescribed fire or mechanical forest stand treatments that can reduce the accumulations of fuels are opposed by some members of society. Collaboration among the supportive but sometimes conflicting interests of the involved parties is necessary to resolve any difficult conflicts and thus provide more unified management of ponderosa pine forests.

    Neary, Daniel G.; USDA Forest Service, Rocky Mountain Research Station (Arizona-Nevada Academy of Science, 2014-04-12)
    In the quest to develop renewable energy sources, woody and agricultural crops are being viewed as an important source of low environmental impact feedstocks for electrical generation and biofuels production (Somerville et al. 2010, Berndes and Smith 2013). In countries like the USA, the bioenergy feedstock potential is dominated by agriculture (73%) (Perlack et al. 2005). In others like Finland the largest potential comes from forest resources. Forest bioenergy operational activities encompass activities of a continuing and cyclical nature such as stand establishment, mid-rotation silviculture, harvesting, product transportation, wood storage, energy production, ash recycling, and then back to stand establishment (Neary 2013). All of these have the potential to produce varying levels of disturbance that might affect site quality and water resources but the frequency for any given site is low (Berndes 2002, Shepard 2006, Neary and Koestner 2012). Agricultural production of feedstocks involves annual activities that have a much higher potential to affect soils and water resources. The way forward relative to assessing the soil and water impacts of bioenergy systems and the sustainability of biomass production rests with three approaches that could be used individually but are more likely to be employed in some combination (Neary and Langeveld 2013). These approaches are: (1) utilizing characteristics that can be quantified in Life Cycle Assessment (LCA) studies by software, remote sensing, or other accounting methods (e.g.,greenhouse gas balances, energy balance, etc.; Cherubini and Strømman 2011); (2) measuring and monitoring ecosystem characteristics that can be evaluated in a more or less qualitative way (e.g., maintaining soil organic carbon) that might provide insights on potential productivity and sustainability, and (3) employing other proactive management characteristics such as Best Management Practices that are aimed at preventing environmental degradation.

    Neary, Daniel G.; USDA Forest Service, Rocky Mountain Research Station (Arizona-Nevada Academy of Science, 2014-04-12)

    Ffolliott, Peter P.; Univ Arizona (Arizona-Nevada Academy of Science, 2014-04-12)
    The role of the Arizona Water Resources Committee and the goal of the Arizona Watershed Program in the early watershed management activities of the state are presented in the introduction of this paper to place its contents in perspective. The Arizona Watershed Resources Committee was a “citizen's advisory committee” that was formed in 1956 to assist in implementing the recommendations made in historic Barr Report to increase water yields and enhance the other natural resources found on the watersheds in the Salt and Verde River Basins of north-central Arizona (Fox et al. 2000). The Barr Report had been released to the public in the form of a short summary publication (Part I) and a more detailed and comprehensive document (Part II), both with the intriguing title of “Recovering Rainfall - More Water for Irrigation,” in the fall of 1956 (Barr 1956a, 1956b, respectively). Contents of the report supported the belief of members of the Arizona Water Resources Committee and many other people that the state's watersheds were in “bad shape” while providing what was called a “scientific basis” for improving these conditions by more intensive watershed management to primarily increase streamflow volumes. The Arizona Watershed Program was a collaborative initiative of the Arizona Water Resources Committee, the Watershed Management Division of the Arizona State Land Department, and the U.S. Forest Service and their cooperators to investigate the effects of vegetative management practices on the hydrologic processes affecting water yields and incorporate the findings obtained into watershed management practices (Fox et al. 2000). It was planned that this general goal would be met by three “highly integrated” programs – a research program, an action program, and a public relations program. Findings of the research and action programs have been reported by Ffolliott and Thorud (1974, 1975), Hibbert (1979), Baker and Ffolliott (1998), Baker (1999), Neary et al. (2002, 2008), DeBano et al. (2004), Solomon and Schmidt (1981), and others. A main component of the public relations program – the Arizona Watershed Symposia – is the focus of this paper.

    Ffolliott, Peter P.; Brooks, Kenneth N.; Univ Arizona; Univ Minnesota (Arizona-Nevada Academy of Science, 2014-04-12)
    Urbanization has been a significant cause for the fragmentation of wildland watersheds since the early 1950s. Furthermore, it is anticipated that urban developments will account for additional losses of natural landscapes into the 21st century. The National Resource Inventory of the U.S. Department of Agriculture indicated that millions of acres of forests, woodlands, agricultural croplands, and other open spaces were converted to urban and other developed areas in the 5 years beginning in 1992 as the rate of urbanization increased when compared to the earlier 10-year period (Alig et al. 2004). Aligned with a projected increase of more than 120 million people in the United States by 2050, urban developments will grow substantially into the future with the fastest rate in the western and southern regions. How urbanization impacts on hydrologic processes and how these impacts might be mitigated when necessary is the focus of this paper.
  • Hydrology and Water Resources in Arizona and the Southwest, Volume 44 (2015)

    Unknown author (Arizona-Nevada Academy of Science, 2015-04-18)

    Schmidt, Carly H.; Environmental Science and Management, Northern Arizona University. (Arizona-Nevada Academy of Science, 2015-04-18)
    Ecological restoration has yet to gain an indepth understanding of the social dynamics that inform restoration design and enable improved watershed performance in urban environments. The Rio Salado Environmental Restoration Project is unique in that the scale of the project expands to new reaches of the Salt River with each successful venture. The 40-year project has been most successful in recent years due to innovative strategies that capitalize on public outreach and inclusion. Adoption of multi-purpose objectives that include partnerships, public stakeholders, and learning achievement have contributed to the project's success. The ability of the restored system to withstand flood events is one of the many examples demonstrating the project's qualifications as a model for future urban restoration efforts. Lessons about the social dynamics that inform urban restoration success have the potential to augment scientific learning in ecological restoration.

    Burke, Megan; Northern Arizona University, Flagstaff, Arizona (Arizona-Nevada Academy of Science, 2015-04-18)
    This paper evaluates the historical growth of the Las Vegas Wash, its subsequent degradation, and the current efforts to restore and stabilize its channel. The Las Vegas Valley Metropolitan Area is located in the Mohave Desert in a drainage basin surrounded by mountain ranges. This drainage basin and its dynamic system of stream channels constitute the Las Vegas Watershed in which the Wash is located. The condition of the Las Vegas Wash is unique, as is a perennial stream that evolved from an ephemeral wash in response to the rapid urbanization and subsequent production of treated wastewater input into the stream channel. The situation has created a series of wetland ecosystems along the Wash, and valuable riparian habitat in such an arid environment. The Wash and its associated wetlands system provide a variety of ecological services to the city of Las Vegas, including storm water conveyance, wastewater effluent filtration, flood protection, and a green space for residents to enjoy. However, continuous increase in volume and intensity of the stream flow has resulted in severe channel degradation and bank erosion in numerous locations along the stream channel. After an examination of the historic and present-day conditions of the Wash and its restoration activities, this essay suggests that future evaluations of the Las Vegas Wash case study may provide evidence to support the propagation of collaborative management efforts.

    Klotz, Jason; Tecle, Aregai; School of Forestry, Northern Arizona University, Flagstaff, AZ (Arizona-Nevada Academy of Science, 2015-04-18)
    This paper is concerned with restoring the quality of water in some portions of the San Pedro River. There are high concentrations of bacteria in some parts of the San Pedro River. Our aim is to find ways of improving the situation. Specifically, there are two objectives in the study. The first one attempts to identify the possible sources of the bacterial contamination and assess its trends within the watershed. The second objective is to determine appropriate methods of restoring the water quality. The main water quality problem is nonpoint source pollution, which enters the stream and moves along with it. The magnitude of the problem is affected by the size and duration of the streamflow, which brings bacteria-laden sediment. The amount of sediment brought into the system is large during the monsoonal events. At this time, the streamflow becomes highly turbid in response to the organic and inorganic sediments entering the system. Based on research done for this paper, the amount of bacterial concentration is strongly related to turbidity. Best management practices (BMPs) have been designed and implemented to restore the water quality problem in the area. The BMP's consist of actions such as monitoring, educational outreach, proper signage, and other range/watershed related improvement practices. Other issues that contribute to the increasing amount of bacteria that are briefly addressed in this paper are bank and gully erosion, flood control, and surface water and streamflow issues that occur on the stream headwaters.

    Kursky, Joshua; Tecle, Aregai; Northern Arizona University, Flagstaff, AZ (Arizona-Nevada Academy of Science, 2015-04-18)
    Hart Prairie is a high-elevation upland riparian ecosystem on the west slope of the San Francisco Peaks in northern Arizona. The location is unique, not only as an upland riparian area in the semi-arid Southwest, but also for having a wet meadow ecosystem dominated by Bebb willow (Salix bebbiana). The ecosystem has experienced a high degree of change since the time of Euro-American settlement. Along with fire suppression, increased wild ungulate herbivory rates, and conifer encroachment into a historically short-grass prairie, several humaninduced changes have been made to the topography of the watershed. Stock tanks, an earthen berm with associated diversion channels, and a road that cuts perpendicularly across the direction of water flow near the base of the watershed have contributed to the altered drainage patterns and the decreased water availability to the flora and fauna in the area. As a result, the Bebb willows and the associated meadow vegetation are at risk. Most of the willows, which constitute the majority of the canopy in the ecosystem, are at a decadent, over-mature stage that allows a limited recruitment of younger plants (Maschinski 1991, Waring 1992). Under these conditions, the plant community may die off leading to the loss of this rare riparian area forever. Research on restoration efforts have been undertaken since the mid-1990s on The Nature Conservancy’s Hart Prairie Preserve and the adjacent US Forest Service Fern Mountain Botanical Area. This paper summarizes the efforts that have been made; most of which targeted to improve the low germination rates of willow seeds, and to restore the geomorphology and surface flow patterns to their pre-disturbance conditions.

    MacDonald, Kit; U.S. Forest Service, Kaibab National Forest, Williams, AZ (Arizona-Nevada Academy of Science, 2015-04-18)
    Stream and watershed restoration projects have become increasingly common throughout the U.S., and the need for systematic post-project monitoring and assessment is apparent. This study describes three stream and watershed ecological restoration projects and the monitoring and evaluation methods employed or planned to evaluate project successes or failures. The stream and watershed restoration and evaluation methods described in this paper may be applicable to projects of similar types and scales. Rivers and streams serve a variety of purposes, including water supply, wildlife habitat, energy generation, transportation and recreational opportunities. Streams are dynamic, complex systems that not only include the active channel, but also adjacent floodplains and riparian vegetation along their margins. A natural stream system remains stable while transporting varying amounts of streamflow and sediment produced in its watershed, maintaining a state of “dynamic equilibrium.” (Strahler 1957, Hack 1960). When in-stream flow, floodplain morphology, sediment characteristics, or riparian vegetation are altered, this can affect the dynamic equilibrium that exists among these stream features, causing unstable stream and floodplain conditions. This can cause the stream to adjust to a new equilibrium state. This shift may occur over a long time and result in significant changes to water quality and stream habitat. Land-use changes in a watershed, stream channelization, installation of culverts, removal or alteration of streambank vegetation, water impoundments and other activities can dramatically alter ecological balance. As a result, large adjustments in channel morphology, such as excessive bank erosion and/or channel incision, can occur. A new equilibrium may eventually be reached, but not before the associated aquatic and terrestrial environment are severely impaired. Stream restoration is the re-establishment of the general structure, function and self-sustaining characteristics of stream systems that existed prior to disturbance (Doll et al. 2003). It is a holistic approach that requires an understanding of all physical and biological processes in the stream system and its watershed. Restoration can include a broad range of activities, such as the removal or discontinuation of watershed disturbances that are contributing to stream instability; installation of control structures; planting of riparian vegetation to improve streambank stability and provide habitat; and the redesign of unstable or degraded streams into properly functioning channels and associated floodplains. Kauffman et al. (1997) define ecological restoration as the reestablishment of physical, chemical and biological processes and associated linkages which have been damaged by human actions.

    Haberkorn, Matt; Phoenix College Bioscience Department, Phoenix, AZ (Arizona-Nevada Academy of Science, 2015-04-18)
    Ephemeral drainage plant communities of the Sonoran Desert compose a highly significant yet relatively unexplained portion of the ecosystem. Eighty-one percent of all southwestern and 94% of Arizona drainages are categorized as ephemeral drainages (Levick et al. 2008). Small but significant portions of the bajada environment are also composed of ephemeral drainages. These drainages carry out important landscape scale functions in water movement, groundwater recharge, nutrient movement and cycling, sediment transportation, geomorphology, plant habitat, seed disbursement, as well as wildlife habitat and corridors. In decades past, Sonoran Desert bajada research relating the physical earth sciences to ecology has focused on explaining upland plant community patterns along this landform (Yang and Lowe 1956, Phillips and MacMahan 1978, Key et al. 1984, McAuliffe 1994, Parker 1995, McAuliffe 1999). This body of research, however, has very little information pertaining to ephemeral drainages dissecting the upland bajada environment. The bajada geomorphic environment is a composition of geomorphic surfaces of varying soil development proceeding away from a mountain (Peterson 1981, McAuliffe 1994). Each of these geomorphic surfaces is characterized by a unique lithology, slope, age and degree of argillic and caliche soil horizon development. Generally, geomorphic surfaces containing highly developed argillic or caliche soil horizons are found near the mountain while surfaces of undeveloped soils are furthest away from the mountain. Depending on the bajada, local geomorphic history, however, may result in different landscape scale patterns of geomorphic surfaces and soil development. This physical environment forms the template from which the ephemeral drainage develops its channel morphology, hydrology and botanical associations. It was expected that the various geomorphic surfaces composing the bajada found at the study sites would determine the specific channel morphology, hydrology and plant community associations of the examined ephemeral drainage. The goal of this study was to explain (1) channel morphology, (2) hydrology or ephemeral flow patterns and (3) plant communities found along the ephemeral drainage. Plant communities of drainages were also compared to upland communities. These factors were then utilized to give an overall explanation for the distribution of hydrogeomorphic and botanical associations found along the bajada ephemeral drainage.

    Tecle, Aregai; School of Forestry, Northern Arizona University, Flagstaff, Arizona 86011 (Arizona-Nevada Academy of Science, 2015-04-18)
    Dams are structures constructed across rivers to control their flows. The main objectives for building dams are to capture and store the surface flow from rivers and runoff from adjacent and upstream watersheds in artificial lakes or reservoirs and eventually release the stored water as needed. The system may be designed for purposes such as flood control, hydroelectric power generation, and providing freshwater for drinking and irrigation. Reservoirs may also serve as sanctuaries for fish and wildlife and for providing recreational activities such as swimming, fishing, and boating (Colorado River Research Group 2014). However, there are also many drawbacks to building dams that need to be considered. Dams displace people from their homes, flood productive areas, destroy ecosystems and /or impair services, inundate precious historical and cultural artifacts and eliminate important wildlife sanctuaries. The subject of this paper is the Colorado River and the effects of its extensive damming projects on downstream ecosystems and the environment. The Colorado River is the major river in the arid and semi-arid southwestern United States and northwestern Mexico. It is a 1,470-mi (2,352-km) river with its main headwaters in the Rocky Mountain National Park in north-central Colorado. It is the international boundary for 17 mi (27 km) between Arizona and Mexico in the southwest (U.S. Bureau of Reclamation, Lower Colorado Region 2015). The Colorado River system, including the Colorado River, its tributaries, and the lands that these waters drain, is called the Colorado River Basin. It drains an area of 246,000 mi2 (637,000 km2) that includes parts of seven western U.S. states (Arizona, California, Colorado, Nevada, New Mexico, Utah, and Wyoming) and two Mexican states (Baja California and Sonora) (Fig. 1). Three-fourths of the Colorado River Basin is in federal lands comprised of national forests, national parks, and Indian reservations. The drainage Basin's total runoff is about 24,700 ft3 (700 m3) per second (Colorado River Commission of Nevada 2006, Colorado River Research Group 2014). The river is the primary source of water, which comes mostly from snowmelt in the Rocky Mountains, for a region that receives little annual precipitation. For more than a thousand years, the Colorado River has been a central feature in the history and development of the southwestern part of the United States. During this period, management efforts in the Colorado River Basin embody society's struggle to overcome conflicts between competing interests over a shared water resource. First, there have been Native Americans who irrigated their crops with water from the river (Glenn et al. 1996). One tribe, the Cocopah Indians who reside in the delta region fished and farmed there for about 2,000 years. Unfortunately, the present Colorado River is often drained dry by upstream demands before reaching this part of Baja, California (Glenn et al. 1992, Zielinski 2010). In spite of this situation, irrigation is still one of the main uses of the Colorado River, especially on its lower portion where it supports one of the most extensive irrigated agriculture in the United States. Other equally important uses are generating hydroelectric power, and supplying drinking water to distant urban areas and other communities. For example, water from the Colorado River is diverted eastward across the Rocky Mountains to Denver and other cities in Colorado. The Colorado River Aqueduct carries water to the metropolitan area of Los Angeles, California, and the Central Arizona Project brings water supply to the Phoenix and Tucson areas in Arizona. In addition, the cities of San Diego and Las Vegas and many smaller cities, towns and rural communities in Arizona, Nevada, and California are dependent on the Colorado River for their water supply. All together about 35 million people in the U.S. Southwest and 3 million others in Mexico depend on the Colorado River for their water supply.

    Jemison, Roy; U.S. Forest Service, Southwestern Region, Albuquerque, NM (Arizona-Nevada Academy of Science, 2015-04-18)
    The USDA Forest Service Southwestern Region (FS) manages over 20.5 million acres of forests and grasslands in Arizona, New Mexico and the Texas and Oklahoma panhandles. Water is one of the most beneficial natural resources used on and off these lands by humans, animals and plants. Water on forest and grasslands generally comes from precipitation which arrives in the form of snow or rain, depending on the location and season. On the ground, water infiltrates, ponds, runs off or evaporates, depending on the surface and climatic conditions. In general, precipitation that falls on these lands is free of pollutants. As water moves across and through soils, rocks and other materials it can become polluted by the surfaces it comes in contact with and by materials added to it. Materials added to flowing water in small amounts over time may have little to no harmful effects on the quality of the water. In large amounts and or concentrated, it can be extremely harmful to the quality of the water and users of the water. Common impacts to water quality include increases in temperature, turbidity, nutrient levels and hazardous chemicals. Sources of pollutants on forests and grasslands can be natural and human introduced. Natural sources and causes of pollution can include soil erosion, wildlife waste, concentrations of naturally occurring materials, drought, and flooding. Human sources and causes of pollution can include runoff from roads, trails, tree harvest areas, recreation sites, sewage facilities, livestock, pesticide applications and fuel and chemical spills (USDA Forest Service 2000). A plethora of methods exist to minimize harmful impacts to water quality on forests and grasslands. In 1990, the FS Southwestern Region developed a core set of practices and procedures, that when properly implemented, can be effective at minimizing and mitigating harmful impacts to water quality. The practices and procedures are both administrative and physical, and are collectively referred to as Soil and Water Conservation Practices, also known as Best Management Practices (BMPs) (USDA Forest Service 1990). Even though these BMPs were designed by FS and state resource specialists in the Southwest, they often require adjustments to make them fit site-specific conditions. The BMPs used by the FS Southwestern Region are acknowledged as being effective control measures by the environment departments of the states (Arizona and New Mexico) in which they were developed, as documented in Memorandum of Understandings (MOUs) that exist between the FS and the states.

    Gottfried, Gerald J.; Neary, Daniel G.; Emeritus Scientist, U.S. Forest Service, Rocky Mountain Research Station, Phoenix, AZ; Supervisory Soil Scientist, U.S. Forest Service, Rocky Mountain Research Station, Flagstaff, AZ. (Arizona-Nevada Academy of Science, 2015-04-18)
    The availability of adequate and reliable water supplies has always been a critical concern in central Arizona since prehistoric times. The early European settlers in 1868 initially utilized the ancient Hohokam Indian canal system which drew water from the Salt River. However, the river fluctuated with periods of drought and periods of high flows which destroyed the diversion structures. The settlers proposed a dam to store water and to regulate flows. In 1903, the Salt River Water Users Association was formed and an agreement was reached with the U.S. Government for the construction of a dam on the Salt River at its junction with Tonto Creek. The Salt River drains more than 4,306 square miles (mi2) from the White Mountains of eastern Arizona to the confluence with Tonto Creek. Tonto Creek drains a 1,000-mi2 watershed above the confluence. The agreement was authorized under the Reclamation Act of 1902. The Theodore Roosevelt Dam was started in 1905, completed in 1911, and dedicated in 1911 (Salt River Project 2002). The dam has the capacity to store 2.9 million acre-feet (af) of water. However, between 1909 and 1925, 101,000 af of sediment were accumulated behind Roosevelt Dam (Rich 1961). Much of it came from erosion on the granitic soils from the chaparral lands above the reservoir, and much of the erosion was blamed on overgrazing by domestic livestock. Water users were concerned that accelerated sedimentation would eventually compromise the capacity of the dam to hold sufficient water for downstream demands. The Tonto National Forest was originally created to manage the watershed above Roosevelt Dam and to prevent siltation. The Summit Plots, located between Globe, Arizona, and Lake Roosevelt were established in 1925 by the U.S. Department of Agriculture to study the effects of vegetation recovery, mechanical stabilization, and plant cover changes on stormflows and sediment yields from the lower chaparral zone (Rich 1961). The area initially was part of the Crook National Forest which was later added to the Tonto National Forest. The Summit Watersheds consisted of nine small watersheds ranging in size from 0.37 to 1.23 acres (ac). Elevations are between 3,636 and 3,905 feet (ft). The treatments included: exclusion of livestock and seeding grasses, winter grazing, hardware cloth check dams, grubbing brush, sloping gullies and grass seeding. Protection from grazing did not pro duce changes in runoff or sedimentation. Treatments that reduced surface runoff also reduced erosion. Hardware cloth check dams reduce total erosion, and mulch plus grass treatments checked erosion and sediment movement. Runoff was reduced by the combined treatments (Rich 1961). The Summit Watersheds were integrated into the Parker Creek Erosion-Streamflow Station in 1932.

    Fenner, Patti R.; Friends of the Tonto National Forest, Phoenix, AZ (Arizona-Nevada Academy of Science, 2015-04-18)
    Permanent riparian photopoints (repeat photography of streamside points) are a widely used monitoring method for situations where there are many streams to monitor, and little time to do it. They often display dramatic changes in these dynamic ecosystems – changes that are brought about by management of permitted and non-permitted activities, flood, drought, and fire. Most of all, they help us to learn more about the relationship of riparian areas to uplands, and how riparian ecosystems function.
  • Hydrology and Water Resources in Arizona and the Southwest, Volume 42 (2012)

    Unknown author (Arizona-Nevada Academy of Science, 2012-04-14)

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