Central Arizona Project Canal Research Articles

Human activities influence mule deer use of overpasses across multiple scales

AbstractAnthropogenic linear infrastructures (ALIs), including roads, railways, and canals, provide important resources to humans, but they can affect wildlife through habitat fragmentation and reduced movement through landscapes. To mitigate these effects, overpass crossing structures (i.e., overpasses) can facilitate wildlife movement across ALIs and maintain landscape connectivity. Human activities can potentially influence spatial and temporal patterns in wildlife use of overpasses; however, little information is available about human–wildlife interactions across some types of ALIs. Using remote wildlife cameras, we evaluated human and mule deer (Odocoileus hemionus) use and interactions at 43 overpasses along the Central Arizona Project canal in Arizona, USA, during 2 seasons (warm and cool) from February 2021 to February 2022. Mule deer exhibited spatial avoidance of human activities at overpasses, although the effect varied across seasons and types of human activity. At a broad scale, the presence of recreationists at overpasses did not exclude mule deer from using overpasses to cross the canal; however, human presence reduced mule deer detection probability in the warm season. At a fine scale, mule deer decreased use of overpasses as activity associated with canal personnel (i.e., security and maintenance workers) increased in the cool season. For both seasons, mule deer exhibited greater overlap in daily activity patterns with recreationists compared to canal personnel. Further, mule deer shifted daily activity patterns to be more active earlier in the morning at sites with high amounts of recreational use compared to sites with lower recreational use. Because human activities can influence mule deer crossings at overpasses, managers might consider minimizing human activities at crossing locations to increase wildlife use and promote wildlife movement across canals and other types of ALIs.

Damming ephemeral streams in the Sonoran Desert, Arizona, USA: biogeomorphic analysis of riparian area growth

In this study, two ephemeral streams are compared in assessing bio-geomorphic change to channels intersected by the Central Arizona Project (CAP) canal. Water and sediment are fully or partially restricted to move downstream due to the CAP canal, which acts as a dam to these streams. Upstream of traversed channels, vegetation cover has increased over time causing the development of a green-up area. Along the canal, several channels remain longitudinally connected via culvert or overchute to the downstream sections of the stream channels. The two streams examined both had longitudinal connectivity, but only one of the streams had a green-up area upstream. Field work and channel surveys reveal that this is due to the culvert’s peak discharge outflow. The stream with a developed green-up area had a culvert size that is approximately three times less than the discharge of this ephemeral stream causing the partial damming upstream during flow events. Green-up zones slowly enlarge over time as bed levels and adjacent desert surface heights increase from continual sediment deposition upstream causing the floodplain to laterally increase due to overbank flooding. It is estimated that the green-up area for the partially dammed stream will increase by approximately 1570 m2 over the next 36 years. Suggestions for urban and agricultural development are presented in this paper in relation to these dynamic green-up areas. Understanding biogeomorphic processes along dammed ephemeral streams lends valuable insight to riparian conservation efforts and future urban development plans in desert regions.

Biogeomorphic Relationships and Riparian Vegetation Changes Along Altered Ephemeral Stream Channels: Florence to Marana, Arizona

This study examines riparian vegetation cover changes along ephemeral channels due to the emplacement of the Central Arizona Project (CAP) canal. Two research questions examined are the following: (1) How has riparian vegetation changed over the course of twenty-eight years due to altered flow conditions? (2) How has channel morphology affected changes in vegetation cover? Five Landsat TM images acquired in 1982, 1989, 1996, 2003, and 2010 were classified. The average change of vegetation cover per 0.5-km section over the twenty-eight-year period is approximately 100,436 m2 over 25.5-km length of the canal on the upstream section. In addition, the total amount of vegetation cover increase in the twenty-eight years over the 25.5-km length of the canal is approximately 5,122,239 m2. Larger streams experienced a greater increase in vegetation cover upslope than smaller streams. In addition, streams of similar width dimensions that were completely closed off resulted in greater vegetation cover than streams that were semiconnected. A significant relationship between changes in vegetation green-up and channel widths was examined. Results from this study suggest that there is a quasi-linear relationship between channel widths and increases in vegetation cover for altered and impounded channels due to the presence of the CAP canal.

Applying Water-Level Difference Control to Central Arizona Project

The Central Arizona Project (CAP) has been supplying Colorado River water to Central Arizona for roughly 25 years. The CAP canal is operated remotely with a supervisory control and data acquisition (SCADA) system. Gate-position changes are made either manually or through the use of automatic controls with a controlled-volume approach. In this paper, the writers examine the potential application to the CAP canal of water-level difference control, a new feedback canal-control method. The main objective of this method is to keep the downstream water-level errors in equal pools. The control model is a multiple input and multiple output (MIMO) system, and the controller is solved as a linear quadratic regulator (LQR). A feed-forward routine called volume compensation was also used to route the flow changes. Simulation results show that this method is stable and can deal with different kinds of changes relatively quickly. For small changes, the water-level difference controller can operate well even without rou...

Use of Crossings over the Tucson Aqueduct by Selected Mammals

The Central Arizona Project canal system could restrict movements of mammals across Avra Valley, Arizona. However, the Wildlife Mitigation Corridor was established to provide access for animals over the Tucson Aqueduct ofthe Central Arizona Project and allow movement of animals across Avra Valley. We recorded tracks of desert mule deer (Odocoileus hemionus eremicus), collared peccaries (Pecari tajacu), and coyotes (Canis latrans) in and out of the Wildlife Mitigation Corridor from August 1996 through July 1997 to determine if animals used the corridor more or less than other canal crossings (i.e., bridges). Deer and collared peccaries used crossings in the corridor more than those outside of the corridor. There was no significant difference between use of crossings by coyotes. Crossings adjacent to water catchments received the highest use by herbivores.

Impact of Ozone Treatment on Selected Microbiological Parameters

A pilot plant study was conducted to evaluate the effects of ozonation on the quality of Colorado River water delivered to the Phoenix (Arizona) Union Hills Water Treatment Plant through the Central Arizona Project canal. Raw and finished water were monitored for basic chemical water quality parameters and for microorganisms including total coliforms, heterotrophic plate count, enteric viruses, Giardia and Crvptosporidium cysts. Ozone, applied through diffusion contactors in dosages optimized to provide the required CT (concentration x contact time) value, was used as a primary disinfectant in two of the four 10 gpm (37.8 L/min) treatment trains.