A toxicity reduction evaluation of the Santa Margarita River Watershed with an emphasis on pyrethroid pollution

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dc.contributor.authorCarroll, Sara E.
dc.contributor.authorVail, Christopher
dc.date.accessioned2025-08-15T01:18:38Z
dc.date.available2025-08-15T01:18:38Z
dc.date.issued2009
dc.description.abstractA Toxicity Reduction Evaluation (TRE) is used to clarify the source of toxicity within a stream, creek, or river and suggest remediation efforts. Due to upstream development and an increase in toxicity in water samples collected, the California Regional Water Quality Control Board (RWQCB) issued a Monitoring and Reporting Program (MRP) in 2004 for stormwater runoff within the Santa Margarita River Watershed. A MRP required Riverside County to conduct bioassessments and a Toxicity Identification Evaluation (TIE). Sampling design, data collection, and analysis for bioassessments was conducted through collaboration with MACTEC Engineering and Consulting. Toxicity testing of water samples for a TIE was done in collaboration with Nautilus Environmental. The biological community of benthic macroinvertebrates which makes up a portion of the ecological composition of Santa Margarita River Watershed was shown to be significantly impacted in both Temecula Creek and Murrieta Creek. The results of the bioassessments further showed that the greatest biological impact on the macroinvertibrate community was in Murrieta Creek. TIE data analysis showed that pyrethroid toxicity fluctuates in the wet weather season in both Temecula Creek and Murrieta Creek- from October through March- in correlation with stormwater runoff. TIE data analysis also showed that the highest average pyrethroid toxicity occurs in Temecula Creek. The land uses surrounding the tributary creeks were then used to indentify sources of pyrethroid pollution in order to suggest effective remediation efforts. The data showed that both agricultural and urban pesticide users are the main factors in pyrethroid toxicity within this watershed. Remediation efforts including: agricultural drainage ditches, porous pavement, bioswales, and community outreach and education were proposed in order to reduce pyrethroid pollution in the Santa Margarita River Watershed.
dc.identifier.urihttps://hdl.handle.net/20.500.11803/4582
dc.language.isoen
dc.publisher.institutionNational University (NU)
dc.subjectEnvironmental engineering
dc.titleA toxicity reduction evaluation of the Santa Margarita River Watershed with an emphasis on pyrethroid pollution
dc.typeThesis
thesis.degree.disciplineEnvironmental Engineering
thesis.degree.grantorNational University (NU)
thesis.degree.levelMasters
thesis.degree.nameMaster of Science
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