Total Maximum Daily Load

A Total Maximum Daily Load (TMDL) is a type of water quality regulation, which limits all of the sources of pollutants to a water body in order to restore and protect beneficial uses of that water body. TMDL regulations are part of the federal Clean Water Act and are enforced by U.S. Environmental Protection Agency (EPA), State Water Resources Control Board, and Los Angeles Regional Water Quality Control Board. All bodies of water in the state of California, including Los Angeles Outer Harbor, are assessed at regular intervals to see whether they are meeting their beneficial uses. If not, the water body is listed as impaired for that beneficial use and must be addressed with a TMDL.

 

 

The State of California is developing specialized regulations for sediment quality in the marine environment. These are known as Sediment Quality Objectives and are being developed in two phases: direct effects and indirect effects. The direct effects of these objectives assess the health of the benthic (sea bottom) community through three measurements: the benthic community itself, chemical analysis of the sediment, and an assessment of sediment toxicity. The indirect effects of these objectives assess the effects of sediments on animals that can accumulate and concentrate contaminants known as bioaccumulation, such as fish that are consumed by humans. These objectives attempt to set limits on sediment conditions that are protective of human health taking into account the transfer of contaminants from the sediment up through the food chain. An important element is the linkage between the sediment and bioavailable contamination; this linkage varies from site to site, even within the harbor.

 

The Los Angeles Harbor Bacteria TMDL-Inner Cabrillo Beach and Main Ship Channel (Bacteria TMDL) is designed to protect the beneficial use of recreational water contact and protect human health. Bacteria levels are assessed in TMDLs by means of indicator bacteria, which are sampled five days per week at two compliance points at Inner Cabrillo Beach and once per month in the Main Channel. The standards for indicator bacteria were developed by EPA and the State of California has adopted them. The Bacteria TMDL took effect in 2005 with a compliance timeframe of five years.  Since 2005, the Main Channel has been in compliance. However, Inner Cabrillo Beach has not met the standards for indicator bacteria and efforts continue to bring the area into compliance.

 

 

Inner Cabrillo Beach has had a long-standing issue with exceedances in the indicator bacteria. Beginning in 2000, the Port and other departments of the City of Los Angeles have worked to investigate and eliminate sources of the bacterial exceedances. The efforts to eliminate the sources of bacteria have included extensive studies of the storm drain and sewer infrastructure.  Housekeeping Best Management Practices were assessed and upgraded as necessary. The sand on the beach was completely replaced with coarse grain sand to improve drainage. A rock jetty was removed to improve circulation. In addition, bird exclusion structures were constructed to keep birds away from the swimming area. The total amount spent on bacteria issues at the beach is in excess of $23 million. Although these exhaustive efforts have been undertaken, exceedances of indicator bacteria have continued at ICB. However, the presence of human sewage-related bacteria has been dramatically reduced and studies show that most of the bacteria are coming from birds.

 

Extensive studies have shown that Inner Cabrillo Beach is likely eligible for a Natural Source Exclusion, which is possible under TMDL regulations if human sources of bacteria have been controlled to the extent possible and are no longer a risk to public health. The Port is conducting a series of special studies to show whether the beach is eligible for a Natural Source Exclusion. Studies will have to demonstrate that the risk of infection to swimmers is actually less than predicted by the indicator bacteria levels, meaning that most of the indicator bacteria are coming from non-human sources.

The Dominguez Channel and Greater Los Angeles and Long Beach Harbor Waters Toxic Pollutants TMDL (Harbor Toxics TMDL) covers all of San Pedro Bay, Dominguez Channel Estuary, and Los Angeles River Estuary. It was promulgated by EPA and the State and took effect in March, 2012. This TMDL includes all of the listed water body impairments within the area, which amount to more than seventy pollutant-water body combinations. All of the listed impairments are in the sediment, not in the water column. The contaminants in the sediment are considered to be a source to the animals that live in the sediment, as well as a source to animals higher in the food chain.

 

 

The Harbor Toxics TMDL designates a group of responsible parties including the City of Los Angeles, the City of Long Beach, their respective ports, and several smaller cities upstream of the Harbor area. The responsible parties for the greater harbor waters have formed a regional monitoring coalition to cover the required monitoring aspects of the TMDL. As part of the required monitoring, the regional monitoring coalition aligns with a program coordinated by Southern California Coastal Water Research Project called the Southern California Bight Monitoring Program. The Bight Program takes place every five years and involves comprehensive sampling of the area from the Mexican border to Point Conception. Samples are taken in San Pedro Bay at an extensive network of stations and then analyses are undertaken using the direct effects these protocols. Sediment Quality Objective-type sampling takes place apart from the Bight Program as well, in two-year intervals. Other aspects of the required monitoring that take place at shorter intervals include water sampling for the list of TMDL-related chemicals, and fish tissue sampling. The Port of Los Angeles, working together with the Port of Long Beach, has also untaken a comprehensive series of voluntary special studies with the goal of better understanding the sources and effects of pollution and building a linked model. The linked model consists of the following components: hydrodynamic and sediment transport, chemical fate, and bioaccumulation. Special studies include fish tracking through implanting acoustic transmitters in White Croaker and California Halibut, measuring organic chemicals in stormwater runoff and ambient harbor waters at ultra-low detection levels, and comprehensive sediment and food web chemical analysis.

 

 

The ports of Los Angeles and Long Beach, in coordination with the State of California Los Angeles Regional Water Quality Control Board, designed and performed a comprehensive series of special studies in order to establish a site-specific sediment quality objective for human health (fish tissue) in the harbor. The group, known as the Harbor Technical Working Group, also examined issues related to Harbor Toxics TMDL compliance and oversaw the completion of the harbor hydrodynamic, sediment transport, chemical fate, and bioaccumulation model (linked WRAP model). The files here represent technical reports from that effort as well as some background material.