EPA Workshop Discusses Complex Criteria for Malibu Watershed TDML Requirements
• The Public Has Until Jan. 22 Deadline to Submit Written Comments Addressing Issues in the Draft Document
BY SUZANNE GULDIMANN
On Jan. 14, the United States Environmental Protection Agency held a public workshop to describe the draft Total Daily Maximum Load requirement, or TDMLs, for the Malibu Creek watershed. The purpose of the workshop was “to give information and provide an opportunity for the public to get clarification on the proposed TMDLs currently out for public comment.” The event was not a public hearing and testimony was not recorded, according to the EPA staff report.
The opportunity to ask questions was welcomed by water quality activists, who have indicated that the massive draft document, which compiles numerous water quality studies and makes the case for more stringent water quality criteria, is challenging to wade through.
However, the time and location—3 p.m. in downtown Los Angeles—made the event a challenge for Malibu residents to attend.
Determining the TMDLs is a complex process that involves assessment of toxicity, nutrients, dissolved oxygen, algae, sediment, and other related constituents-natural and industrial-that impact water quality.
“The United States Environmental Protection Agency Region IX is establishing TMDLs for Malibu Creek and Lagoon in the Los Angeles Region,” the draft document begins. “USEPA
was assisted in this effort by the Los Angeles Water Quality Control Board.
“A variety of water quality impairments have been identified in the watershed. This report specifically addresses the impaired benthic biota in the Malibu Creek main stem and Malibu Lagoon, while discussing conditions throughout the watershed that may impact these impairments. The remainder of this section presents the regulatory background, a description of the elements of a TMDL, and a brief discussion of the physical setting.”
According to the draft document, “the Malibu Lagoon was originally included in the 1998 listing for benthic community effects impairment. According to California State Water Resources Board, Los Angeles Region (Personal Comm. LB Nye, Aug. 9, 2012), the basis of the impairment listing for benthic community impacts in Malibu Lagoon was due to one of the few documented survey of the benthic community, in Chapter 6 of “Enhanced Environmental Monitoring Program at Malibu Lagoon and Malibu Creek” (Ambrose et al., 1995). This discussion provides a summary of the benthic invertebrate results and analyses provided in the report; the sampling method and other details are not provided in this TMDL, and instead further interest should be directed to the Chapter 6 of the report itself.
A total of three different invertebrate groups were surveyed in the 1993-1994 sampling effort, including zooplankton (small floating species in the water), infauna (species living in the Lagoon sediment), and large invertebrates (e.g.,shrimp,crabs).
According to the draft report, “The observations and results of the 1993-1994 sampling effort for benthic invertebrates suggest that Malibu Lagoon ranks ‘poorly at this trophic level when compared to less disturbed southern California estuaries.’”
The controversial State Parks’ Malibu Lagoon Restoration and Enhancement Project appears to be a key part of the TDML finding, according to the report: “Supporting information for the 2010 integrated report against delisting this listing for Malibu Lagoon stated that readily available data and information, and weight of evidence, conclude there is ‘sufficient justification against removing this water segment-pollutant combination from the section 303(d) list.’”
The report states that “this conclusion is based on the staff findings that: The Malibu Lagoon Restoration Feasibility Study Final Alternatives Analysis describes restoration measures for Malibu Lagoon.”
“These proposed restoration efforts, if fully implemented, are anticipated to correct the conditions, which allow the negative indicator species to thrive.
The Regional Board “decided against moving the benthic community effects listing in Malibu Lagoon from the TMDL required portion of the 303(d) list to the [sic] being addressed by action other than TMDL portion of the 303(d) list.”
The source of impairment is indicated as “hydromodification.”
“Comprehensive evaluation of the available data confirm impairments for benthic macroinvertebrates and benthic community effects in Malibu Creek and Malibu Lagoon, respectively,” the draft states.
“The sedimentation listing in Malibu Creek is confirmed by both the turbidity data analyses in which results were an order of magnitude above reference sites as well as the calculated 38 percent change in sedimentation rate from natural conditions.
“Multiple stressors were evaluated related to these impairments. The key stressors impacting the biota (both directly and indirectly) are sedimentation and nutrient loading. In addition, nutrient data from the last 10 years suggest that the nutrient concentration numeric limits from the 2003 TMDL are not quite stringent enough to attain beneficial uses and that new targets should be set year-round and reduced to address the benthic-macroinvertebrate and benthic community effects impairments in Malibu Creek and Lagoon, respectively.
Other portions of the massive document include discussions of Tapia winter discharges that increase nitrate levels; the impact of anthropogenic pollution, including illegal dumping, pesticides and herbicides; issues like unstable banks; sedimentation; ammonia concentrations; algae that forms during the summer months, and naturally generated nutrients from the Modelo formation, which leaches nitrates and phosphates into the watershed.
“Malibu Creek watershed has unique geology with many areas of marine sediments with the Modelo formation,” the report states.
“For nitrate-N, median concentrations at potential reference sites without significant anthropogenic disturbance appear to be less than 0.03 mg/L and mostly less than 0.01 mg/L for many sites both in and outside the Modelo formation…”
Malibu water quality activists have recently begun calling for naturally occurring bacteria and nutrients to be taken into account in the equation used to determine TMDL.
They argue that zero-level bacteria is an unachievable goal and that nutrients and bacteria from birds, kelp wrack and other natural sources is an integral part of the ecosystem that cannot and should not be eliminated.
The entire draft document for the EPA’s TMDL requirements for the Malibu Creek watershed is available online at: http://www.epa.gov/region9/water/tmdl/pdf/EpaMalibuCrkLagoonTMDL2012-12-12MainReport.pdf
The deadline for public comments is Jan. 22, at or before 5 p.m. Comments should be addressed to Cindy Lin at firstname.lastname@example.org