The effect of a massive wastewater discharge on nearshore ocean chemistry
An opportunity to study the effect of a massive wastewater discharge on a nearshore ocean environment arose in 2015 over a 42-day period when the City of Los Angeles diverted 9.4 billion gal of treated wastewater effluent from an outfall located 5 mi in the Pacific Ocean to a 1-mi backup in the Santa Monica Bay (SMB). SMB is a heavily used waterbody and is home to many marine organisms. To understand the impact of this diversion on human health and on SMB ecosystem, samples of the wastewater effluent, the receiving seawater, and sediments from around the backup outfall were analyzed, among others, for metals, semivolatile organic compounds (SVOC), nutrients, and total organic carbon (TOC) during the diversion project. Results show that these parameters were present at levels below local water quality guidelines (i.e., not enough to cause health or environmental concerns). In the effluent, metal levels were < 10 μg/L except Zn (23 ± 9.9 μg/L); phosphate, ammonia-nitrogen, organic-nitrogen, and TOC levels were 3.48 ± 0.37, 42.7 ± 5.3, 4.7 ± 1.4, and 19.0 ± 4.9 mg/L, respectively. In seawater and sediments around the backup outfall, metal levels were < 1.5 μg/L and < 25 mg/kg, respectively. Apart from 4,4’-DDE, SVOCs were not detected in sediments. To assess whether changes to native levels of pollutants in SMB occurred due to the diversion project, pre-diversion and post-diversion datasets were compared statistically. No significant differences were found between the two datasets (p > .05, paired t test), meaning the diversion did not change the SMB chemistry.
KeywordsHyperion 1-mi diversion Metals Semivolatile organic pollutants Nutrients Santa Monica Bay
The authors acknowledge their colleagues at the Environmental Monitoring Division for their support and the City of Los Angeles for the funding and environmental stewardship.
Role of the funding source
The funding source is named in the acknowledgement. The funding source only contributed to the study design, but not to the data analysis or the writing of this report, and makes no endorsement of the report’s finding and conclusion.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies with human participants or animals performed by the authors.
- APHA. (2012). Standard methods for the examination of water and waste water (22nd ed.). Washington, DC: American Public Health Association.Google Scholar
- CASQA (2015). Zinc sources in California urban runoff. California Stormwater Quality Association. https://www.casqa.org/sites/default/files/library/technical-reports/zinc_sources_in_california_urban_runoff.pdf. Accessed 03 Oct 2017.
- Chartrand, A. (1986). Montrose Chemical Corporation: strategies for managing a widespread point source contaminant: in Proceedings of the symposium, Managing Inflows to California’s Bays and Estuaries, Monterey, CA.(pp. 50–56). The Bay Institute of San Francisco, Sausalito, CA.Google Scholar
- CLA (2006). 5-Mile Outfall inspection and diversion to the 1-Mile Outfall fact sheet. City of Los Angeles. http://planning.lacity.org/eir/8150Sunset/References/4.K.2.%20Wastewater/WW.05_Hyperion%20Treatment%20Plant_10.9.13.pdf. Accessed 19 Oct 2017.
- CLA (2015a). Environmental Monitoring Plan for Diversion of Secondary-Treated Effluent from the 5-Mile Outfall to the 1-Mile Outfall for the EPP Header Rehabilitation Project. City of Los Angeles. http://sccoos.org/media/filer_public/9f/77/9f779193-67c6-4656-901d-2dd08e4092f5/2015_diversion_event_monitor_plan_final_150723_amended__withappendices.pdf. Accessed 19 Oct 2017.
- CLA (2015b). Santa Monica Bay Biennial Assessment Report 2013–2014. City of Los Angeles.https://www.lacitysan.org/san/sandocview?docname=cnt010038. Accessed 19 Oct 2017.
- CLA (2017). Fall 2015 Hyperion Treatment Plant Effluent Diversion to the 1-Mile Outfall Comprehensive Monitoring Program Final Report. Environmental Monitoring Division, Bureau of Sanitation, Department of Public Works, City of Los Angeles.Google Scholar
- Froescheis, O., Looser, R., Cailliet, G. M., Jarman, W. M., & Ballschmiter, K. (2000). The deep-sea as a final global sink of semivolatile persistent organic pollutants? Part I: PCB in surface and deep-sea dwelling fish of the North and South Atlantic and the Monterey Bay Canyon (California). Chemosphere, 40, 651–660. https://doi.org/10.1016/S0045-6535(99)00461-0.CrossRefGoogle Scholar
- Hammer, Ø., Harper, D. A. T., &Ryan, P. D. (2001). PAST: Paleontological statistics software package for education and data analysis. Palaeontologia Electronica 4(1): 9pp. http://palaeo-electronica.org/2001_1/past/issue1_01.htm. Accessed 22 Oct 2017.
- Harding, L. W., Howard, M. D. A., Kudela, R. M., & McLaughlin, K. (Eds.). (2017). Tracking impacts of anthropogenic nutrient inputs in an urban coastal ecosystem during a wastewater diversion in the southern California bight. Estuarine, Coastal and Shelf Science, 186, 163–276.Google Scholar
- Howard, M. D. A., Sutula, M., Caron, D. A., Chao, Y., Farrara, J. D., Frenzel, H., Jones, B., Robertson, G., McLaughlin, K., & Sengupta, A. (2014). Anthropogenic nutrient sources rival natural sources on small scales in the coastal waters of the Southern California Bight. Limnology and Oceanography, 59, 285–297. https://doi.org/10.4319/lo.2014.59.1.0285.CrossRefGoogle Scholar
- Howard, M. D. A., Kudela, R. M., & McLaughlin, K. (2017). New insights into impacts of anthropogenic nutrients on urban ecosystem processes on the Southern California coastal shelf: Introduction and synthesis. Estuarine, Coastal and Shelf Science, 186, 163–170. https://doi.org/10.1016/j.ecss.2016.06.028.CrossRefGoogle Scholar
- LARWQCB (2010). Waste discharge requirements and National Pollutant Discharge Elimination System permit for the City of Los Angeles, Hyperion Treatment Plant discharge to the Pacific Ocean. Los Angeles Regional Water Quality Control Board.https://www3.epa.gov/region09/water/npdes/pdf/ca/HtpAdoptedPermitOdrNoR4-2010-0200-11-23-10.pdf. Accessed 19 Oct 2017.
- Looser, R., Froescheis, O., Cailliet, G. M., Jarman, W. M., & Ballschmiter, K. (2000). The deep-sea as a final global sink of semivolatile persistent organic pollutants? Part II: organochlorine pesticides in surface and deep-sea dwelling fish of the North and South Atlantic and the Monterey Bay Canyon (California). Chemosphere, 40, 661–670. https://doi.org/10.1016/S0045-6535(99)00462-2.CrossRefGoogle Scholar
- MacGregor, J. S. (1974). Changes in the amount and proportions of DDT and its metabolites, DDE and DDD, in the marine environment off southern California, 1949–1972. Fishery Bulletin, 72, 275–293.Google Scholar
- NOAA (1988). National status and trends program for marine environmental quality. A summary of selected data on chemical components in sediments collected during 1984, 1985, 1986 and 1987. NOAA Technical Memorandum NOS OMA 44. NOAA Office of Oceanography and Marine Assessment, Rockville, Maryland: National Oceanic and Atmospheric Administration.Google Scholar
- Noble, M. A., Rosenberger, K. J., Hamilton, P., &Xu, J. P. (2009). Coastal ocean transport patterns in the central Southern California Bight, in Lee, H.J., and Normark, W.R., eds., Earth science in the urban ocean: the Southern California continental borderland: Geological Society of America Special Paper 454, p.193–226. https://doi.org/10.1130/2009.2454(3.3).
- Paraskevas, P. A., Giokas, D. L., & Lekkas, T. D. (2002). Wastewater management in coastal urban areas: the case of Greece. Water Sci Technol, 46, 177–186.Google Scholar
- Schorder, M. (1997). Pollutant and organic matter content in sediment size fractions. In Freshwater contamination, Proceedings of Rabat Symposium S4, IAHS Publ. No. 243.Google Scholar
- SWRCB (2012). Water quality control plan: ocean waters of California (Ocean Plan). California State Water Resources Control Board. http://www.waterboards.ca.gov/water_issues/programs/ocean/docs/cop2012.pdf. Accessed 19 October 2017.
- US EPA (2012). Santa Monica Bay Total Maximum Daily Loads for DDTs and PCBs. http://www.swrcb.ca.gov/rwqcb4/water_issues/programs/tmdl/Established/SantaMonica/FinalSantaMonicaBayDDTPCBsTMDL.pdf. Accessed 19 Oct 2017.
- US EPA Methods 200.7 (1994), 200.8 (1994), 350.1 (1993), 351.2 (1993), 608 (1984), 625 (1999), 1631E (2002), 1640 (1997), 1668C (2010), 3050B (1996), 3620B (1996), 3650B (1996), 6010B (1996), 7470A (1994), 7471A (1994), 8081A (1996), 8082 (1996), 8270C (1996) are at https://www.epa.gov/measurements/collection-methods. Accessed 19 Oct 2017.
- Word, J. Q. (1976). Biological comparison of grab sampling devises. In Southern California Coastal Water Research Project, Annual Report for 1976 (pp. 189–194). Costa Mesa: SCCWRP.Google Scholar
- Yao, Q., Wang, X., Jian, H., Chen, H., & Yu, Z. (2015). Characterization of the particle size fraction associated with heavy metals in suspended sediments of the Yellow River. International Journal of Environmental Research and Public Health, 12(6), 6725–6744. https://doi.org/10.3390/ijerph120606725.CrossRefGoogle Scholar
- Zaldivar, E.C. (2015).Los Angeles sanitation response for Materials Of Sewage Origin on Santa Monica Bay beaches. http://clkrep.lacity.org/onlinedocs/2015/15-1218_rpt_BOS_11-24-2015.pdf. Accessed 19 Oct 2017.