Deadly Power

A Case for eliminating the impacts of the South Bay Power Plant on San Diego Bay and ensuring better environmental options for the San Diego/Tijuana Region.

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Executive Summary

The South Bay Power Plant has been responsible for severely degrading the San Diego Bay ecosystem with thermal and chemical pollution and by killing a wide range of juvenile, larval, and adult organisms in its cooling system for more than 40 years. These impacts are severe and continual. This degraded condition is now so long-standing that it is considered the "baseline" for South Bay. This grossly inefficient plant is also a source of air pollution and a visual blight on the community.

Plans will be developed soon for a replacement for the South Bay Power Plant. We cannot let the degradation and destruction of San Diego Bay continue through the use of bay water for cooling. Now is the time to stop the "cooling that kills." The evidence in this report makes it clear that:

• The negative environmental impacts from the South Bay Power Plant to San Diego Bay are significant;
• There are feasible, viable, and protective alternatives for replacement of the South Bay Power Plant;
• The current permitting structure is inadequate; and
• Government must act now to eliminate the damage to San Diego Bay.

The member organizations of the San Diego Bay Council, representing 22,000 San Diegans, are committed to act through community involvement, regulatory participation, and legal action, to ensure that the South Bay Power Plant is torn down and its damaging impacts to sensitive South San Diego Bay are ended. The Bay Council urges agencies with authority over the South Bay Power Plant to aggressively pursue the following actions:

1. Build a State of the Art, Dry-Cooled Power Plant to Replace the South Bay Power Plant
   The South Bay Power Plant must be torn down and replaced as soon as possible with a more efficient, dry-cooled plant and there must be aggressive commitments to conservation and clean, renewable energy sources. This will result in less air and water pollution and use of less hazardous materials in the region. Officials should establish an enforceable time line to phase out the South Bay Power Plant.


2. Provide Comprehensive and Meaningful Regulation of the Existing Power Plant
   The South Bay Power Plant's National Pollution Discharge Elimination System (NPDES) permit is up for a five-year renewal. In the near-term, the Regional Water Quality Control Board must require new, more protective requirements for the discharges into San Diego Bay. The Regional Board should include a permit condition or resolution that clearly states that any replacement plant should not use Bay water for cooling and that impacts from current practices should be fully mitigated and the Bay should be restored. The monitoring regime for the new permit should include discharge and receiving water limits and monitoring for all constituents known to be present in the discharge. It should also be designed to fully assess impacts on beneficial uses.


3. Recognize the Impacts of the South Bay Power Plant on South San Diego Bay
   Impacts to marine life of South Bay will not be addressed until we recognize the extent of the problem. South Bay is heavily impacted by the power plant discharges and cooling process itself. South San Diego Bay should be added to the 303(d) list of "impaired" water bodies so that it receives priority action for protection.

The South Bay Power Plant is a steam electric power generating facility located at the far southeast shore of San Diego Bay, surrounded by sensitive mudflat habitat. The plant uses what is called a once-through wet-cooling system that draws cooling water from San Diego Bay. This heated cooling water is then discharged back into the Bay. At full capacity, 601 million gallons of water are discharged back into the Bay each day. Other California power plants use this cooling method, but draw from and release water to the open ocean, where the volume of the water body greatly exceeds the amount being used and where the heated water is more quickly dissipated.

South San Diego Bay is a sensitive marine environment, highly vulnerable to thermal, chemical and other pollution sources. The south Bay environment is most vulnerable in summer, the time of year that the SBPP releases the most thermal pollution because of increased summer energy demands. Water discharged from the plant can reach temperatures over 100ºF, a lethal temperature for fishes and other marine life. The plant also releases toxic chemicals in discharged water, including copper, nickel, zinc, chromium and chlorine. The high temperatures exacerbate the effects of chemical pollution on marine life.

There is no maximum temperature limit for SBPP discharges. Between 1974 and 2000, average discharge temperatures have risen over 10ºF in both summer and winter. Permitted increases in temperature between intake water and water discharged from the SBPP have risen from 12.5ºF to 15ºF. The higher water temperature decreases the amount of dissolved oxygen in the water and, at the same time, increases the metabolic rate of animals, which increases their oxygen demand. The plant discharges dead plants, fishes, shellfish and other organisms back into the Bay and the decay of these plants and animals further reduces oxygen levels.

The South Bay Power Plant has been disrupting the ecosystem of South San Diego Bay for more than 40 years. Roughly 20% of the water in the South Bay is drawn into the plant every day. Early life stages of marine plants and animals also are drawn into the cooling water system, where they are subjected to mechanical damage, as well as chemical, temperature and pressure shock. The loss of early life stages of fish, shellfish and other invertebrates, and other microscopic plants and animals that form the base of the food chain may affect the overall ecological balance of the Bay. Millions of these organisms are lost in the Power Plant each year.

Adult fish and invertebrates in the vicinity of the SBPP intake are drawn into the intake structure and impinged, or trapped, by either a "trash rack" or a series of screens. A 1979-1980 study considered impingement and estimated that 28,174 individual fish were killed in the plant in 1979.

A major concern is the use of up to 4,100 pounds of chlorine per month for the purposes of killing marine life in the intake water. The highly chlorinated water is then discharged back into the Bay. Almost all species of animals are hit hard by chlorine, and this effect is exacerbated in a shallow, poorly circulated environment like the South Bay. In addition to its immediate effects, chlorine is now known to break down, complex with other substances, and form new compounds such as chlorinated organics. These chlorinated organic compounds can remain toxic for aquatic life for long periods. The SBPP uses more chlorine in summer, compounding the effects of higher summer water temperature, less dissolved oxygen, and the greater toxicity of other chemicals.

The SBPP also releases an estimated 400-1020 pounds of copper, a heavy metal that is highly toxic to marine life and which is known to accumulate in fish and shellfish, into the Bay each year. Nickel concentrations in the cooling water have also been significant. Zinc waste plates, used for corrosion control, release zinc into the cooling water. For fishes, a decrease in oxygen levels of the water increases the apparent toxicity of zinc and copper. Water temperature is possibly the most important factor affecting zinc toxicity: the higher the temperature, the shorter the survival time. The juvenile inhabitants of South Bay are more sensitive to these metals than adult animals.

Eelgrass (Zostera marina) forms a distinct marine habitat providing vital shelter and food for many bay inhabitants. For some reason, eelgrass is absent in the vicinity of the plant, yet plentiful west of the plant and in other areas of the South Bay. Eelgrass is highly dependent on sufficient light to thrive, and declines in seagrass abundance have been linked to decreasing water transparency. Without the power plant discharge, we would expect a resurgence of eelgrass beds.

One problem associated with securing reliable information about the impacts of the plant is that the data we have is not independent of the discharger. Many of the existing studies are suspect because the discharger funded them, with a significant interest in the conclusions of the studies. Independent assessment of the impacts of the power plant is needed.

The South Bay Power Plant energy conversion efficiency is about 38% compared to modern day power plants, which have design efficiencies upward of 56%. A new plant that generates the same amount of electricity would use significantly less natural gas and emit less air pollution. Efficient use of natural gas is critical given the negative air quality impacts of burning oil and the limited supply of natural gas. Further, two-thirds of the cost of operating a fossil fuel plant is the cost of fuel.

There are feasible, viable, and protective alternatives to once-through wet-cooling. Dry-cooling has been available for more than 40 years and has been used in all climates with several in arid regions of Mexico and the United States. Dry-cooling uses air instead of water to cool the low-pressure steam leaving the steam turbines. Large radiator-type tube banks are used to transfer heat from the condensing steam to air passing over the tubes. Dry-cooling has no air or water polluting emissions. There is no water evaporation, no visible plume, no thermal discharges, and no particulate air emissions associated with the cooling. Water is only needed for periodic system maintenance and cleaning. Dry cooling could result in reductions in water use by more than 99 percent over once-through wet-cooling. Through such reductions in water use, the need to use water from any sensitive or biologically productive water body is removed. Further, dry cooling does not need to sterilize the water it uses for cooling so the use of chlorine is eliminated.

There are over 600 electric power plants throughout the world that use dry-cooling, including 50 in the United States. These plants are of a variety of sizes, types, and located in a variety of climates including one planned in Otay Mesa.

• The State Water Resources Control Board should
  • Ensure that the updated Thermal Plan provides more protective requirements regarding thermal discharges into state waters. The update should strengthen protections for estuaries and enclosed bays. The new Thermal Plan should prohibit the use of natural surface waters for cooling of power plants since feasible alternatives exist.
  • Add the waters of South San Diego Bay to the 303 (d) list as impaired for heat, chlorine, and copper.


• The Regional Water Quality Control Board should
  • Specifically address requirements on any replacement plant for the SBPP and make clear the intent of the Board for any future proposal. This could be accomplished through a condition in the new NPDES permit or a resolution requiring any reconstruction/repower during this permit duration to carry a "new discharge" designation and, thus, subject to much more stringent requirements.
  • Strengthen the NPDES permit, increase monitoring, and require mitigation for damage caused by the operation of the SBPP in order to ensure protection of beneficial uses in San Diego Bay. The new permit should move closer to the elimination of water quality impacts from the power plant discharges as soon as possible. Essential changes include: establish limits and monitoring requirements for dissolved oxygen and all constituents present in the discharge such as metals and chlorine by-products; relocation of the compliance point to the real point of discharge (i.e. end of the pipe); set maximum temperature limits for the discharge; establish impingement and entrainment limits; establish sediment monitoring; and increase frequency of chlorine monitoring.
  • Ensure that storm water requirements are incorporated into the renewed NPDES permit and strengthened to include, at a minimum, acute toxicity and diversion of storm water from high risk areas.


• The San Diego Unified Port District should renegotiate the lease for the power plant and the Port should ensure that any operator is held to hard and fast deadlines for removal of the SBPP. A requirement should be added that any new plant on Port District tidelands must utilize dry cooling.


• The California Energy Commission should require all new and repowered plants to use dry cooling.


• The San Diego Regional Energy Office should recommend an aggressive Regional Energy Strategy that pursues conservation, efficiency, and clean renewable energy to the maximum extent possible for the San Diego/Tijuana region.

To read the report Deadly Power: A case for eliminating the impacts of the South Bay Power Plant on San Diego Bay and ensuring better environmental options for the San Diego/Tijuana Region in its entirety, please see the Environmental Health Coalition's website at http://www.environmentalhealth.org/