Category Archives: Research Articles

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PIRE Participants Publish in WIRES Water Journal

PIRE collaborators from UC Irvine, the Southern California Coastal Water Research Project, and the University of Melbourne’s Centre for Aquatic Pollution Identification and Management completed an initial study examining the proposed use of recycled waste-water for achieving various environmental and social goals in one Australian watershed. They conclude that, with dedicated public outreach, such an approach might be constructively applied to a variety of water quality problems.

Click the link below for the full article:

Governance Issues in Developing and Implementing Offsets for Water Management Benefits: Can Preliminary Evaluation Guide Implementation Effectiveness?

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UCI Water PIRE researchers published an article describing why dry weather urban runoff negatively impacts water quality along the shoreline of enclosed embayments in southern California, and how the drainage system could be re-engineered (following Australia’s lead) to improve the situation.

See the article (click here) and the press release (

Enclosed beaches along urban coastlines are frequent hot spots of fecal indicator bacteria (FIB) pollution. In this paper we present field measurements and modeling studies aimed at evaluating the impact of small storm drains on FIB pollution at enclosed beaches in Newport Bay, the second largest tidal embayment in Southern California. Our results suggest that small drains have a disproportionate impact on enclosed beach water quality for fi ve reasons: (1) dry weather surface fl ows (primarily from overirrigation of lawns and ornamental plants) harbor FIB at concentrations exceeding recreational water quality criteria; (2) small drains can trap dry weather runoff during high tide, and then release it in a bolus during the falling tide when drainpipe outlets are exposed; (3) nearshore turbulence is low (turbulent diff usivities approx-imately 10 − 3 m 2 s − 1), limiting dilution of FIB and other runoff – associated pollutants once they enter the bay; (4) once in the bay, runoff can form buoyant plumes that further limit vertical mixing and dilution; and (5) local winds can force buoyant runoff plumes back against the shoreline, where water depth is minimal and human contact likely. Outdoor water conservation and urban retrofits that minimize the volume of dry and wet weather runoff entering the local storm drain system may be the best option for improving beach water quality in Newport Bay and other urban-impacted enclosed beaches.

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Professor Sunny Jiang and her PhD student Keah-Ying Lim evaluate the health risks associated with household use of rooftop-harvested rainwater in an article published in the journal Water Research.



•Health risk associated with harvested rainwater for home gardening is evaluated.
•Results indicate the annual risk exceeds U.S. EPA drinking water risk benchmark.
•Comparative risk shows lower risk of applying rainwater than reclaimed water.
•Current risk benchmark should be reconsidered for sustainable water practice.


Health risk concerns associated with household use of rooftop-harvested rainwater (HRW) constitute one of the main impediments to exploit the benefits of rainwater harvesting in the United States. However, the benchmark based on the U.S. EPA acceptable annual infection risk level of ≤ 1 case per 10,000 persons per year (≤ 10-4 pppy) developed to aid drinking water regulations may be unnecessarily stringent for sustainable water practice. In this study, we challenge the current risk benchmark by quantifying the potential microbial risk associated with consumption of HRW-irrigated home produce and comparing it against the current risk benchmark. Microbial pathogen data for HRW and exposure rates reported in literature are applied to assess the potential microbial risk posed to household consumers of their homegrown produce. A Quantitative Risk Assessment (QMRA) model based on worst-case scenario (e.g. overhead irrigation, no pathogen inactivation) is applied to three crops that are most popular among home gardeners (lettuce, cucumbers, and tomatoes) and commonly consumed raw. The infection risks of household consumers attributed to consumption of these home produce vary with the type of produce. The lettuce presents the highest risk, which is followed by tomato and cucumber, respectively. Results show that the 95th percentile values of infection risk per intake event of home produce are one to three orders of magnitude (10-7 to 10-5) lower than U.S. EPA risk benchmark (≤ 10-4 pppy). However, annual infection risks under the same scenario (multiple intake events in a year) are very likely to exceed the risk benchmark by one order of magnitude in some cases. Estimated 95th percentile values of the annual risk are in the 10-4 to 10-3 pppy range, which are still lower than the 10-3 to 10-1 pppy risk range of reclaimed water irrigated produce estimated in comparable studies. We further discuss the desirability of HRW for irrigating home produce based on the relative risk of HRW to reclaimed wastewater for irrigation of food crops. The appropriateness of the ≤ 10-4 pppy annual risk benchmark for assessing safety level of HRW-irrigated fresh produce is questioned by considering the assumptions made for the QMRA model. Consequently, the need of an updated approach to assess appropriateness of sustainable water practice for making guidelines and policies is proposed.

Click Here for the full article.

Click Here for a PDF Download of the article.

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New Article! Changes In Concurrent Monthly Precipitation & Temperature Extremes – Amir AghaKouchak, Zengchao Hao, Thomas Phillips

PIRE’s very own Amir AghaKouchak has just published an article focusing on changes in concurrent monthly precipitation and temperature extremes on the IOPScience website. You can find the full article here:

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