The University of Arizona Water Resources Research Center (WRRC) administers the Section 104b program of the Water Resources Research Act. Funded by the U.S. Geological Survey, 104b provides support for small research projects investigating water issues of importance to the states and the regions. WRRC was provided $55,000 to $60,000 to fund 104b research. Only faculty members at Arizona's state universities are eligible to receive program funding. Four projects received 104b funding:

Project Title: Isotope biohydrology of an ephemeral drainage.
Principal Investigators: David Williams, Kevin Hultine, University of Arizona and David Goodrich, USDA-ARS Southwest Watershed Research Center
Project Description: Although ephemeral channels are integral components of groundwater/surface water systems in arid basins of the Southwest, inadequate knowledge exists of pattern and process relating to water movement through these systems. What is specifically lacking is knowledge on transpiration losses from groundwater and soil by dominant woody riparian species and details of recharge in specific ephemeral drainages. The project will establish a suite of hydrological and ecophysiological isotope studies at Walnut Gulch in southeastern Arizona to characterize the fate of water moving through a representative ephemeral drainage in a semiarid region.
The project takes a multi-disciplinary approach and attempts to relate biological controls on evapo-transpiration to processes of groundwater recharge. Specifically, results will shed light on the magnitude and timing of deep recharge from ephemeral channels to the upper San Pedro watershed aquifer.

Project Title: Approaches to reduce taste and odor problems in drinking water. Principal Investigators: Milton R. Sommerfeld, Tomas A. Dempster, Arizona State University
Project Description: Municipalities in the Phoenix Metropolitan area have experienced taste and odor problems in their drinking water. The problem seems to be increasing, especially during the late summer and extending into winter. Two compounds, 2-methylisoborneol (MIB) and geosim, are generally recognized as causing the unpleasant earthy/moldy taste and odor. Blue-green algae (cyanobacteria) and fungi (actinomycetes) are thought to produce these compounds. This project involves collaboration between operators of Chandler Water Treatment Plant and Arizona State University researchers, with cooperation of Salt River Project
The researchers' approach is to: 1) isolate and culture algae, bacteria and fungi from the treatment plant and at sites in the distribution system in an attempt to identify the specific "culprit" organisms; 2) determine the efficiency of several laboratory control treatment methods (e.g., copper sulfate, chlorine, etc.) on the individual "culprit" organisms; and 3) assess the efficiency of pilot field treatments (physical, chemical, biological) on the control of the specific organisms.

Project Title: Partitioning the causative factors of evapo-sublimation. Principal Investigators: Charles C. Avery, Leland R. Dexter, Northern Arizona University
Project Description: Studies show that sixty to seventy-five percent of the usable water resources for western states originates as snowfall. The accumulated water commonly sits for long periods as snow prior to melting. This exposes it to vapor loss through a number of relatively poorly described and poorly quantified pathways. The researchers refer to the combination of these vapor losses as evapo-sublimation abstraction.
Previous field studies suggest that 1.5 mm of snow water equivalent is lost in northern Arizona during an average, clear winter day. With the large amount of snow accumulated during the winter season, the loss can substantially reduce the available water resources. Current water resource forecasting fails to consider the variables involved in evapo-sublimation. The ratio of snowfall to runoff is therefore immaterial.
The researchers have designed and constructed a cold-chamber based "sublimimeter," a closed box in which snowpack is weighed while subjected to a controlled environment. They are able to control airflow and lamp intensity but have not yet implemented a way to control humidity. Program funding will allow them to build such a device as well as to develop a multiple-regression model.
Experiments will allow the researchers to explicitly separate (partition) critical evap-sublimation variables, identify specific sub-problems for future analysis and construct better physically based models of evapo-sublimation.

Project Title: Physical effects of flood flows on seedling growth and survivorship: comparative responses of native riparian trees and shrubs to saltcedar. Principal Investigators: Julie Stromberg, Crystal Levine, Arizona State University
Project Description: Altered water regimes have caused substantial decline in productivity, species diversity, and extent in many of Arizona's native riparian forests. Some dam managers are attempting to restore native vegetation by prescribing controlled flood flows; timing spring flood flow to coincide with the germination phenology of targeted species. Some of their efforts have achieved notable success.
Unregulated streams of the Southwest typically carry high sediment loads. If deposited on young seedlings by mid-season flooding, the sediment can kill or scour the seedlings. Native seedlings have a high stem growth rate that may reduce the likelihood of complete sediment burial by monsoon-driven flood flows. Similarly, rapid root elongation would provide some insurance against being dislodged by scouring flow. Since flow in southwestern rivers is driven by bi-modal precipitation patterns, native riparian tree species may be better adapted to withstand mid-summer floods than exotics accustomed only to spring floods from melted snow.
The study objectives are: 1) to quantify seedling growth and survival thresholds of four dominant woody riparian species: Fremont cottonwood (Populus fremontii), Goodding willow (Salix gooddinglii), seep willow (Baccharis salicifolia), and tamarisk (Tamarix chinensis) in response to a) simulated flood scour, b) sediment burial, c) water availability, and d) soil texture; 2) to contribute information for development of an effective long-term plan to curtail further colonization by Tamarix and to help re-establish native riparian forest on managed Arizona rivers.