The Effects of Quagga Mussels on Influent Waters at San Diego's Alvarado Water Treatment Plant

Abstract

San Diego drinking water reservoirs that contain water and infrastructure connected to the Alvarado Water Treatment Plant (San Vicente, El Capitan, Murray, Otay, and Miramar) have been negatively impacted by invasive species. San Diego's reservoirs – those of which that are directly connected to the California Aqueduct – have contained quagga mussels since their discovery within the Colorado River system in 2007 (LaBounty, 2007). Events such as the elimination of trophic levels, changing predator-prey interactions, and overall changes in water quality itself are evident within quagga mussel infested waters (Ward, 2010). Conventional water treatment methodologies include primary and secondary treatment to ensure that San Diego distributes clean and safe water to consume. The scope of our research aims to demonstrate that influent waters at the Alvarado Water Treatment Plant exhibit significant differences in turbidity, total suspended solids and total dissolved solids in the years before quagga mussel infestations, as opposed to the years after their colonization. Data of all three constituents was obtained from the city of San Diego, and subsequently separated and averaged by seasons each year. An analysis of variance of both turbidity and total dissolved solids demonstrated that only turbidity was significantly different in the years before (0.85) and after (0.78) the quagga invasion – having a p-value of 0.002 (n = 3,886). Total suspended solids were allocated into two categories of either above or below 1 mg/L; Total suspended solids measurements greater than 1 mg/L ranged between 1.46 and 2.06 mg/L (n = 79). The turbidity of effluent waters is significantly decreasing; however, the seasonal variability of total dissolved solids is becoming increasingly unpredictable.