Source Water Assessment in Drinking Water

Source Water Assessment

A critical step in assuring the quality of drinking water resources is to identify the cause of current or potential contamination problems. Biological threats to drinking water resources include bacteria and pathogens. Chemical threats can include toxic metals, nutrients, pesticides, fertilizers, petroleum products and industrial solvents. Numerous research programs through CSREES and the Land Grant System are working to improve the assessment, tracking and modeling of such contaminants to drinking water resources.

university research facility Bacteria and Pathogens

Pathogens are microorganisms that cause illnesses; they represent a threat to human health if present in drinking water supplies. Scientists often use bacteria as indicators of fecal contamination and pathogen presence. Much research through CSREES and the Land Grant System is examining Bacterial Source Tracking (BST), new methodology that determines the sources of fecal bacteria (e.g., of human, livestock, or wildlife origin) in water samples (details on BST can be found through the Southern Region Water Quality Program ). Identifying the sources of fecal contamination helps to formulate pollution reduction plans that minimize bacterial and pathogenic pollution and ensure the safety of drinking water supplies.

Accomplishments:
Researchers at the University of Georgia determined that geographically-limited host origin databases for BST may not be universally applicable.
A BST project at Oregon State University (Field, 2003) found that the majority of sites tested in the Tillamook watershed were heavily impacted by ruminant rather than fecal pollution. Managers will be better able to target pollution prevention measures.
Fifty strains of Enterococcus bacteria have been isolated for the construction of four BST libraries at Washington State University.

Examples:

A new study at the University of Vermont is investigating how pathogenic bacteria travel through the ground and in irrigation pipes. The research will be used to generate a model of bacterial transport which can be used to predict where bacteria travel with applications in groundwater and irrigation systems.
A new project at Kansas State University is developing BST and watershed modeling tools , evaluating best management practices to abate fecal contamination, and conducting educational programs to restore the water quality of targeted high-priority TMDL stream reaches.
A Florida-Virginia collaboration is generating six fingerprint libraries encompassing three geographic regions - FL; New River Valley, VA; and Shenandoah Valley, VA. Researchers found significant geographic limitations to the methods, Such limitations should be an important consideration when planning BST studies.

In addition to BST, other work is being done on pathogens that threaten drinking water supplies. In particular, the subsurface modeling and transport of Cryptosporidium parvum are receiving much attention among CSREES researchers. Understanding these processes will enable stakeholders to develop strategies to prevent the contamination of drinking water supplies.

Accomplishments:
At Cornell University, C. parvum oocyst viability was similar in two types of calf housing, including solar calf housing (SCH) which had been suggested as a best management practice to control this pathogen.

Examples:

At the University of Hawaii, researchers are examining how soil pH, organic matter, and the salinity of soil pore water affect the attachment behavior of C. parvum oocysts in the variable-charge tropical soils and those in the southeastern United States. Findings from this study will help to ascertain the physical and chemical conditions that enhance or diminish Cryptosporidium oocyst transport through variable charge soils
Scientists at the University of California are studying the capacity of small streams in naturally filtering C. parvum . This work will improve the design of buffer zones and the design of small stream restorations to allow for better pathogen removal. Related work can be found in the UC Davis Groundwater webpages .
Researchers at Yale University are developing a comprehensive understanding of the mechanisms controlling the attachment and transport behavior of C. parvum oocysts in porous media.
Work is being conducted at Cornell University to develop an accurate method to quantitatively determine the effect of watershed management practices and environmental conditions on the risk of human health cause by the transport of C. parvum oocysts into municipal water supplies.

ground water monitoring station Inorganic Contaminants

Arsenic is a semi-metallic element that occurs naturally in rocks, soils, and waters that come in contact with these rocks and soils. Arsenic at high levels in drinking water, either from natural sources or industrial and agricultural pollution, poses potential health threats and is thus receiving attention from CSREES

Example: Research is being conducted to determine the extent of this arsenic problem, its relationship to socioeconomic factors, and treatment devices and alternatives (Walker et al., 2004).

Through a grant from the University of Minnesota, researchers are testing cows in west central Minnesota to research the possible health effects of arsenic on their cows and the potential for arsenic to pass into milk and cheese for human consumption. (Liukkonen et al., 2006)

In collaboration with the 406 CSREES Water Quality Program, groundwater samples were collected from private and small community wells within 5 western states (Wy, Sd, Mt, Co, & Ut) and analyzed for levels of arsenic. The resulting data was then used to create an outreach program with the working partners to establish awareness and address the growing concern of arsenic contamination within many western states. (Roth et al., 2006)

Novel arsenic removal methods which are efficient across a wide range of natural water conditions will be useful. This study, being conducted at the University of Wyoming, could help develop a simple and effective arsenic removal method which would improve the health of people worldwide by improving drinking water quality. (Martinson and Reddy, 2008)

Arsenil™, a natural zeolite-coated nanophase Mn-susbtituted Fe oxide, has high surface reactivity and good water flow property. Also, it is capable of removing As(III) without the use of a pre-oxidation stage. The objective of a study at Southern Methodist University was to test ArsenilTM performance in varying pH, Ca2+ and alkalinity, and silicate containing waters. (Vempati, 2006)

Selenium, a metal also found in natural deposits, may be present in soil at high levels in arid and semi-arid areas in the western U.S. causing potential drinking water problems. Salinity/Selenium was identified by the CSREES Northern Plains and Mountains Region as an issue of regional importance. Research is being conducted to develop alternative strategies to reduce selenium loads and to develop basin-level models for water movement and selenium loadings.

Research in North Carolina is developing improved geochemical models based on simple field measurements (e.g. dissolved oxygen) to monitor and control potential occurrence of natural contaminants in groundwater, such as arsenic, radium, and radon. In addition, reasonable treatment strategies are being presented to residents, as well as examining different states strategies for dealing with natural contaminants in private wells. (Vinson et al., 2008)

Indicates work supported by the USDA-CSREES National Research Initiative Competitive Grants Program .

The intent of this page is not to catalogue all activities, but rather to indicate the types of research activities in this theme across the U.S.