Quantifying sources of aqueous orthophosphate contributing to the headwaters of the Santa Margarita River, Southwestern Riverside County, California
| dc.contributor.author | Pearson, Daniel B. | |
| dc.date.accessioned | 2025-09-18T03:02:51Z | |
| dc.date.available | 2025-09-18T03:02:51Z | |
| dc.date.issued | 2013 | |
| dc.description.abstract | A series of field studies was conducted in Murrieta Creek, Temecula Creek, Santa Gertrudis Creek, Tucalota Creek, Warm Springs Creek, Slaughterhouse Creek, and the Upper Santa Margarita River, Riverside County, California, USA, during the 2012 dry season and the 2011-2012 & 2012-2013 wet seasons. The Santa Margarita River, Murrieta Creek, and Temecula Creek are classified by the State of California Environmental Protection Agency as being degraded due to excess phosphorus, the origins of which are listed as (in part) unknown (Cal/EPA, 2010). This study sought to identify some of the origins of phosphorus in those water bodies. Three primary methods were utilized to evaluate the most biologically available form of phosphorus, orthophosphate (Shaw, et al, n.d.), within the study area: A visual analysis of trends in vegetation within the creek beds and along their banks; discrete grab sampling of creek water to localize sources of significant orthophosphate concentrations; and, sequential time-series sampling of particular locations to more completely characterize orthophosphate near the headwaters of the Santa Margarita River. Among the three sources that make up the headwaters of the Santa Margarita River (Murrieta Creek, Temecula Creek, and an outlet for court-mandated fresh water discharge designated WR-34) the mean concentration of orthophosphate, throughout the 17-month study period, was found to be lowest in WR-34 (0.24 mg/L), nearly double that value in Murrieta Creek (0.44 mg/L), and triple the value in Temecula Creek (0.76 mg/L). These values were found to be significantly different (p < 0.05) from one another. A comparative analysis of Flow-Weighted and Time- Weighted Mean Concentration sampling of all three sources returned unweighted FWMC:TWMC ratios of 2.03 for Murrieta Creek and 0.97 for Temecula Creek. These values suggest that Murrieta Creek is more-heavily influenced by nonpoint sources of orthophosphate, while Temecula Creek is more-heavily influenced by point sources (Heidelberg University, 2005). Water issued by outlet WR-34 is most frequently imported water (S. Cambra, personal communications, January 15, 2013), and it is suggested that the quality of the water is, therefore, heavily influenced by constituents found in the lower reaches of the Colorado River. Due to its construction, however, outlet WR-34 can be treated as a point source of nutrient loading regardless oft he nutrient origins. The ultimate goal of this research is to contribute knowledge to the study of nutrient-loading within local creeks. The knowledge may be used to help reduce the concentration of aqueous orthophosphate at the headwaters of the Santa Margarita River, thereby improving water quality throughout this important watershed. | |
| dc.identifier.uri | https://hdl.handle.net/20.500.11803/4691 | |
| dc.language.iso | en | |
| dc.publisher.institution | National University (NU) | |
| dc.subject | Environmental engineering | |
| dc.title | Quantifying sources of aqueous orthophosphate contributing to the headwaters of the Santa Margarita River, Southwestern Riverside County, California | |
| dc.type | Capstone | |
| thesis.degree.discipline | Environmental Engineering | |
| thesis.degree.grantor | National University (NU) | |
| thesis.degree.level | Masters | |
| thesis.degree.name | Master of Science |