u.s. department of the interior u.s. geological survey integrated water-quality assessment using...

U.S. Department of the InteriorU.S. Geological Survey

Integrated Water-Quality Assessment using

Conventional, Passive-Sampling, and Metabolic Assay Techniques:

Approaching System-Level Understanding of Risk

Valerie Kelly and Kathy McCarthy

U.S. Geological Survey

Oregon Water Science Center, Portland OR

Drinking Water Source Protection

Typically focused on identifying conditions associated with mobilization of contaminants

Based on discrete samples Storm runoff Land use sources—measure effect of

spatial scale within river basin

What is missing? Occurrence of chemicals across range of

temporal scale Synergistic effect of multiple chemicals,

often not measured or detectable

Evaluating an Integrated Approach

McKenzie River High quality drinking water

source for City of Eugene, supplied by Eugene Water & electric Board (EWEB)

Data from USGS reconnaissance study to characterize potential threats

Incorporates storm runoff samples, long-term deployment of passive samplers, and metabolic assay

McKenzie River: a complex system

Elements of system—individual chemicals and their origins Occur across a range of sources and temporal scale Acute storm concentrations versus chronic long-term

concentrations

Interconnections within system—conditions that mobilize and transport chemicals Land use activities interacting with climatic factors

Function of system—describes behavior, many aspects to consider Relative to threat assessment: what is detrimental effect

of chemical mixture?

Overview of Sampling Methods—Sites

• Three sites: two tributaries and McKenzie River intake

• Three time periods: fall 2007 and early/late spring 2010

McKenzie River

Cedar Creek

Camp Creek

Willamette River

Drinking water intake

City of Springfield/Eugene

Overview of Sampling Methods

Discrete samples: analyzed for pesticides, pharmaceuticals (N=176)

Passive samples: analyzed for pesticides, PAHs, PCBs, WWI (N=159) sequester chemicals into

sorbent over 30 days

Metabolic assay: yeast estrogen screen (conducted on passive sampler extracts)

Influence of Land Use

Results for Three Sets of Samples—Elements of System

Number of detections

Results—Looking More Closely at Late Spring 2010

Concentrations Measured in Late Spring 2010

ng/L

Interconnections—Influence of Climate and Flow Conditions

Discrete samples associated with rain event and rising hydrograph, following a mix of spring storm events

Passive sample deployment period included multiple (small) storm events

Discrete sample collected

Discrete samples collected

Daily precipitation at Springfield City Hall

Mean daily streamflow in Cedar Creek

Passive sample deployment

Passive sample deployment

System Function/Behavior—One Measure Yeast estrogen screen assay

Measures estrogenic activity Presumed to be due to combined (synergistic) effect of

endocrine disrupting compounds

Measurable in Cedar Creek but not in Camp Creek or in McKenzie River at treatment plant intake Two replicates: 0.35 and 0.43 ng/L Associated with detections of six potential endocrine

disrupting compounds in passive sample, none in discrete sample

What Have We Learned?

Chemicals are present during discrete runoff events that are not detectable over longer-scale measurements Implies very short term occurrence Limited effect on McKenzie River

Chemicals accumulate over longer-scale periods at concentrations orders of magnitude below conventional analytical techniques Lots going on under the conventional radar screen Present no recognized threat as individual chemicals

Potential estrogenic activity seems to be significantly associated with strong urban signature Other data document persistent occurrence of pesticides in stormwater

discharging to Cedar Creek Suggests synergistic effect of multiple compounds Not detected in McKenzie River We know very little about this issue

Might These Data Be Relevant Elsewhere? Collecting data over range of scale—including spatial

and temporal—provides a more comprehensive view on chemical occurrence Could be expanded to include other river basins

Including metabolic assay provides a relevant measure of effect of chemical mixtures Could be useful to compare relative to quantified mixtures

of chemicals across range of systems

Great potential for collaboration among drinking water providers USGS forming Oregon Drinking-Water Providers Science

Partnership

Acknowledgements

Study funded by U.S. Geological Survey in cooperation with Eugene Water & Electric Board