Occurrence and behavior of wastewater indicators in the Santa Ana River and the underlying aquifers

The occurrence and behavior of wastewater indicator compounds in the Santa Ana River (SAR) water and the underlying aquifer recharged by the SAR has b een studied. The SAR contains a high proportion of tertiary treated wastewa ter effluents, up to 100% during summer and fall. The following water quali ty parameters were quantified: four specific wastewater indicator compounds , ethylene diaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), a n aphthalene dicarboxylate (NDC) isomer, alkylphenol polyethoxy carboxylates (APECs), and selected haloacetic acids (HAAs), nitrate, dissolved oxygen (D O), I)OC, total carbohydrate, and phenolic substances. Statistical analysis indicated that normal distribution was adequate to describe the probabilit y distribution of the constituents in most cases. In the river, the concent rations of wastewater indicator compounds decreased as the fraction of stor m runoff increased. EDTA and NDC were detected in a monitoring well near th e river and in two production wells 1.8 and 2.7 km down gradient with littl e apparent attenuation. By contrast, NTA, APECs, bromochloro- and dibromoac etic acids appeared to be attenuated significantly during infiltration of r iver water and groundwater transport. (C) 1999 Elsevier Science Ltd. All ri ghts reserved.