Attendees
Catherine Tyrrell/ Michael Lyons/Xavier Swamikannu, Los
Angeles Regional Water Quality
Control Board
Mitzy Taggart, Heal the Bay
Lauma Jurkevics, California Coastal Commission
Rick Cameron, Port of Long Beach
Guang-Yu Wang, Santa Monica Bay Restoration Project
Tim Piasky, Los Angeles County Department of Public Works
Gretchen Honan, CH2M-Hill
Ken Schiff, Southern California Coastal Water Research Project
Dorothy Soule, University of Southern California
Mel Suffet, University of California, Los Angeles
The meeting focused on a discussion of existing sources of stormwater monitoring data for the Ballona Creek watershed and Marina del Rey Harbor and the proposed scope of work for the Army Corps of Engineers' study.
Gretchen Honan made some introductory remarks on the scope of work. One objective of the study is to identify sources of contaminants; sampling may be necessary to determine if the marina is a source of contaminants to the Entrance Channel sediments, or if the sediment contamination is derived entirely from material coming down Ballona Creek. It might be useful to conduct sediment sampling in the back bay of the marina or in Ballona Creek; if so, what parameters should be tested? LACDPW suggested collecting toxicity data from each major tributary to track sources of contamination; this may be useful, but the objective would need to be defined.
UCLA (Mel Suffet) has been looking at stormwater runoff upstream (Centinela, Sepulveda) and comparing the data to Ballona Creek. The only County flow gauge is on Ballona Creek, so UCLA arranged to have flow gauges installed on smaller side channels. All metals were found to have low concentrations in the soluble fraction; 95% or more of the metals were associated with suspended solids. Stormwater runoff was sampled during 1998 (March event during an El Nino year) and in 1996. The 1996 data suggested that storms earlier in the season had more toxicity than later storms; during the 1998 El Nino storm, less toxicity overall was observed. In 1998, there may be a first flush effect, but then metal concentrations drop off even though flow is increasing, then concentrations increase later. Loading estimates showed that about 30 kg of lead were discharged in 1996 vs. 300 in 1998. Need more studies to correlate with possible BMPs for removal of contaminants; also need to identify what comes off parking lots and other sources. Need to combine GIS with land use and runoff data (Michael Stenstrom's project – still in the development stage). Not much sediment remains within storm channels, so it might not be productive to try to sample sediments from within Ballona Creek or other tributaries.
USC (Dorothy Soule) has been sampling Marina del Rey + PCH Bridge in Ballona Creek since the late1970s (3 years of data), and 1985-95 (sediment data, 1 to 2 times a year before and after the rainy season). There is evidence that material gets into the marina from Ballona Creek (either directly during storms or via tidal action). The soil around Marina del Rey is believed to be contaminated from historic sources, so even if we clean up sediments within the marina, it may become recontaminated quickly. The Oxford area at the back of the marina has very contaminated fill. Water backs up in the Oxford basin and there are higher lead concentrations there. Chlordane is likely coming from the soils under the Silverstrand houses. Historically, termite exterminators cleaned their tanks into the Harbor near there. Washington Street drain contributes runoff to marina. In terms of sediment contamination in the Marina del Rey Entrance Channel, the marina probably is much less significant as a source of contaminants than Ballona Creek, but we really don't know how much the surrounding land used contribute to contamination of the marina. Camp Dresser McKee collected stormwater data for the Playa Vista development, but they are not willing to share information.
Dr. Soule said the breakwater acts as a cork to keep debris in the harbor. She has observed Ballona debris flows collecting at the Administration dock. The storm drains in the marina are a significant source of fine sediments with concentrated metals. With a small amount of rain the contaminants sit in the slips; with more rain they collect in a sandbar by the lagoon near the entrance and with significant amounts of rain they migrate to the entrance channel.
In Dr. Soule's opinion, more frequent dredging will reduce the contaminant problem. That is, remove the bar before clean material is contaminated by build up of unclean sediments. Emphasized that data alone are not as important as understanding the dynamics of the circulation and tidal interactions.
SCCWRP (Ken Schiff) made estimates of pollutant loads in the Southern California Bight associated with stormwater runoff, including Ballona Creek, about ten years ago. They also looked at toxicity of dry weather flows in Ballona Creek about five years ago. The study on the effects of stormwater runoff on receiving waters (off the mouth of Ballona Creek and Malibu Creek), conducted for Los Angeles County Department of Public Works, is nearing completion. An evaluation of molecular markers for urban runoff, conducted as part of Bight '98, is about one year from completion; also, about 7 sites within Marina del Rey were sampled as part of Bight '98 (including sediment chemistry, sediment toxicity, benthic infauna, demersal fish and macroinvertebrate communities, but not necessarily every component at each site).
RWQCB (Xavier Swamikannu) indicated the major source of lead and TRPH to be likely the freeways. CalTrans has data on pollutant concentrations off freeways. LACDPW is collecting data from critical sources (light industry), which are predominant in the watershed -- Look at LA County Stormwater Monitoring Report 9 1997-98. Also Industrial Permits in the MDR watershed may have data on 2 to 3 thousand facilities once we isolate a sub-watershed for further study.
General Discussion
Discussion on type of testing – water column verses pore water from sediments (latter is preferred); also where to test – watershed or in marina/channel? Toxicity testing up in the watershed may not explain the cumulative contamination in sediments at Marina Del Rey. Concentration of contaminants is in the fines. A "fines" sediment budget is needed so fixes can be concentrated where most fines occur. Dr. Soule commented that in wet weather flow toxicity is not there – dilution and moved farther offshore. Dry weather flows stay near the coast and are toxic.
Overall, the group believes that we need to figure out the sources of sediment to Marina del Rey and the Entrance Channel (i.e., develop a sediment transport budget) and distinguish between dry weather and wet weather loadings. There are multiple existing data sources that no one has collected and reviewed for their usefulness and compatibility. The first step for the Corps of Engineers should be to do a focused literature collection and review effort to determine future sediment or water sampling needs. Catherine Tyrell emphasized that a working hypothesis should first be developed to guide the literature review (i.e., the majority of the lead contamination comes from Ballona Creek…). Two different directions were discussed: 1) what are the sediment pathways and transport routes, and 2) what are the watershed sources – which sub-watersheds and which land uses are the most important to focus on. Developing a decision tree was recommended as a method to keep track of where the Corps effort fits into the overall process of source reduction information needs.
ACTION ITEMS
All attendees were asked to e-mail to Gretchen Honan (ghonan@ch2m.com) a list of water quality or sediment sampling studies or data sets that they have or know about for the area.
Tim Piasky, Gretchen Honan and Tony Risko are to meet to refine the Corps scope of work.
Next meeting: to be announced.
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