MALIBU WATER QUALITY Figure 2- Civic Center Area
resources within a designated area, typically a watershed(s) (Pincetl, 1994). The LARWQCB claimed that the water quality in the nearshore environment and within several creeks and streams that flowed through the City of Malibu was being impacted by individual septic flows (LARWQCB, 2009). In particular, Malibu Creek was of interest to the Regional Board as well as many non-profit environmental groups including Heal the Bay and Surf Riders (Fig. 2).
Based upon the Water Quality Control Plan – Los Angeles Region (Basin Plan for the Coastal Watersheds of Los Angeles and Ventura Counties) of 1994, it was determined that several water resources were impacted (LARWQCB, 1994). In 2009, the LARWQCB issued a staff report to prohibit on-site wastewater disposal systems in the Civic Center Area of Malibu (CCAM) (LARWQCB, 2009). This was based in part on the coliform bacteria count and eutrophication of the Malibu Lagoon, as well as indicator bacteria found on Malibu Beach. This led to the development of total maximum daily load (TMDL) for total nitrogen and bacteria to be established for Malibu Creek, Lagoon and Beach (USEPA, 2006). Research into the source of the bacteria and nitrogen determined it to be primarily from on-site septic systems. Many coastal communities have expe- rienced such issues (Artan, Orhon & Sozen, 1995; Desimone & Howes, 1996; Geary & Whitehead, 2001; Moeller, et. al., 2003; Carroll & Goonetilleke, 2005; Kudela, et. al. 2017).
Materials and Methods
After nearly two decades of fighting with the Regional Board about on-site septic
16 TPG •
Apr.May.Jun 2021 Figure 3- Well Location within the Civic Center Area and Cross-Section Line.
www.aipg.org
systems versus larger municipal sys- tems, the City of Malibu signed a mem- orandum of understanding with the LARWQCB (2011). As a result, the City embarked on a series of hydrogeology studies of the CCAM (Fig. 3). These studies incorporated a wide variety of data collection with the idea of creating a calibrated regional groundwater model of the Civic Center and Winter Canyon Areas of Malibu (Ambrose & Orme, 2000; Bay & Schiff, 2003; Jay, et al., 2009; Stone, 2010). The purpose of the groundwater model was to evaluate the flow throughout the CCAM and Winter Canyon Areas of Malibu (Fig. 2), the groundwater – surface water interaction and the interaction (discharge) with the Pacific Ocean. In addition, the flow model was to be used to determine the optimal location and potential volume for treated wastewater injection (through existing individual septic systems, percolation pits and/or injection wells) and other reuses. Understanding the groundwater flow allowed for a better understanding of the interactions between the Malibu
Lagoon, the Creek, and the nearshore area.
This hydrogeology study was conducted by several consul- tants and the United States Geological Survey (USGS) over the course of several years. The study used historical data from geotechnical reports, groundwater investigations, environ- mental cleanup reports, precipitation and evapotranspiration data from Pepperdine University, tidal data from National Oceanographic Atmosphere Administration (NOAA), surface
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