Water quality in the central Arizona basins, Arizona, 1995-98

Abstract

Water-Quality Assessment (NAWQA) Program. Water quality is discussed in terms of local and regional issues and compared to conditions found in the 36 NAWQA study areas, called Study Units, assessed to date. Findings are also explained in the context of selected national benchmarks, such as those for drinking-water quality and the protection of aquatic organisms. The NAWQA Program was not intended to assess the quality of the Nation's drinking water, such as by monitoring water from household taps. Rather, the assessments focus on the quality of the resource itself, thereby complementing many ongoing Federal, State, and local drinking-water-monitoring programs. The comparisons made in this report to drinking-water standards and guidelines are only in the context of the available untreated resource. Finally, this report includes information about the status of aquatic communities and the condition of in-stream habitats as elements of a complete water-quality assessment. Many topics covered in this report reflect the concerns of officials of State and Federal agencies, water-resource managers, and members of stakeholder groups who provided advice and input during the Central Arizona Basins assessment. Basin residents who wish to know more about water quality in the areas where they live will find this report informative as well. THE NAWQA PROGRAM seeks to improve scientific and public understanding of water quality in the Nation's major river basins and groundwater systems. Better understanding facilitates effective resource management, accurate identification of water-quality priorities, and successful development of strategies that protect and restore water quality. Guided by a nationally consistent study design and shaped by ongoing communication with local, State, and Federal agencies, NAWQA assessments support the investigation of local issues and trends while providing a firm foundation for understanding water quality at regional and national scales. The ability to integrate local and national scales of data collection and analysis is a unique feature of the USGS NAWQA Program. The Central Arizona Basins Study Unit is one of 51 water-quality assessments initiated since 1991, when the U.S. Congress appropriated funds for the USGS to begin the NAWQA Program. As indicated on the map, 36 assessments have been completed, and 15 more assessments will conclude in 2001. Collectively, these assessments cover about one-half of the land area of the United States and include water resources that are available to more than 60 percent of the U.S. population.

Assessing the Relative Bioavailability of DOC in Regional Groundwater Systems

“…The surficial Delmarva aquifer system consists of fluvial gravels and sands of largely Pleistocene and Holocene age (Owens and Denny 1979) that generally contain lower amounts of POC, but some horizons are more organic‐rich than others. The sediments of the Central Arizona Basins aquifers consist of alluvial gravels, sands and clays that contain uniformly low amounts of POC (Cordy et al 2000), and this contributes to low DOC‐high DO concentrations in groundwater that may be hundreds or thousands of years old (Winograd and Robertson 1992). Thus, the presence or absence of bioavailable POC in a given aquifer (Figure 2) may have an effect on the observed interaction of DOC and DO (Tesoriero and Puckett 2011).…”

Seasonal and longitudinal water quality dynamics in three effluent-dependent rivers in Arizona

“…Aquatic invertebrates can also be affected by low oxygen levels, with tolerant worms (Oligochaeta: Martins, Stephan & Alves, 2008 ) and fly larvae ( e.g., Chironomus , Chironomidae: Lencioni et al, 2008 ) replacing sensitive mayflies (Ephemeroptera) and stoneflies (Plecoptera) near effluent outfalls ( Hamdhani, Eppehimer & Bogan, 2020 ). In fact, a previous study from the Santa Cruz and Salt Rivers reported low oxygen levels and only a few tolerant invertebrate taxa near effluent outfalls ( Cordy et al, 2000 ). However, wastewater treatment plants supplying these reaches have since been upgraded, and recent findings from the Santa Cruz River demonstrate a robust aquatic invertebrate community with few apparent dissolved oxygen limitations ( Eppehimer et al, 2020 ).…”

“…, Webb et al, 2014 ). However, prior to wastewater treatment plant upgrades, water quality was generally poor and aquatic biodiversity was low ( Cordy et al, 2000 ; Walker, Goforth & Rector, 2005 ; Sonoran Institute, 2017 ). In particular, high water temperatures, low dissolved oxygen levels, and elevated concentrations of ammonia have been cited as the cause of low aquatic biodiversity in effluent-dependent streams ( e.g.…”

Arsenic Concentrations in Ground and Surface Waters across Arizona Including Native Lands

“…The geologic profile and climate of Arizona lend itself to naturally occurring valuable mineral deposits and fertile agricultural lands. Unfortunately, both of these factors plus the large and primarily rural nature of Arizona contribute to issues securing clean water resources that are safe for human consumption (Cordy et al 2000). The arsenic water quality information represented in the USEPA and National Water Quality Monitoring Council databases demonstrated water resources that exceeded the USEPA MCL of 10 ppb were widely distributed across the state, with most exceedances located in the central and southern regions (Figures 3–6).…”