Executive Summary

Evaluation of copper and tributyltin containing compounds. EH 95-07.

Part one - Program to Regulate Copper and Tributyltin

Nita A. Davidson


In February 1994, AB 3394 was introduced by Assembly Member Byron Sher (D, Palo Alto) to address excessive discharges of copper and tributyltin into bays, estuaries, and inland surface waters. The bill would have allowed the California Regional Water Quality Control Boards (Regional Boards) to prohibit the sale, use, and discharge of copper-containing root control compounds, and copper or tributyltin containing cooling water additives, once the Regional Boards determined that these compounds 1) interfered with obtaining water quality objectives or 2)prevented compliance with national pollutant discharge elimination system (NPDES) permits. The sponsors of the bill assumed that the Regional Boards have the authority to regulate the sale or use of pesticides on a local basis. However, under current law, the Department of Pesticide Regulation (DPR) has exclusive authority to regulate the sale and use of pesticides throughout California and customarily does so through administrative rather than legislative processes.

After several discussions with Assembly Member Sher, his staff, and representatives from Publicly Owned Treatment Works (POTWs), the California Environmental Protection Agency and DPR determined that an administrative solution would quickly achieve the goals of AB3394, under DPRs current regulatory authority (Department of Pesticide Regulation, 1994). In August 1994, DPR, along with the cooperation and assistance of the State Water Resources Control Board (State Board) and Regional Boards, established a high-priority program to address the sale and use of copper- and tributyltin-containing pesticides.

The Copper and Tributyltin Program

The copper and tributyltin program was created to develop an administrative solution to concerns raised about the water quality impacts in the San Francisco Bay Area by pesticides containing copper and tributyltin. Staff of the Environmental Monitoring and Pest Management Branch of DPR formed a work group to accomplish the tasks involved in evaluating the copper and tributyltin problem. Based on information at hand, the work group identified the San Francisco Bay Area counties in the Regional Board's San Francisco Bay Region (Region 2) as areas of greatest concern. These counties include (1)San Francisco, (2)Santa Clara, (3)San Mateo, (4)Alameda, (5)Contra Costa, (6) Solano, (7) Napa, (8)Marin, and (9)Sonoma.

Searching the literature and requesting information from interested parties

Staff assembled pertinent literature, collecting in-house publications and reprints of journal articles contributed by the Palo Alto Regional Water Quality Control Plant (RWQCP) (a POTW) and Region 2. To ensure that important references had not been overlooked, staff obtained 169 abstracts on environmental monitoring of copper and tributyltin. Information compiled from these references is included in parts Two and Three of this report, which describe the fate of copper and tributyltin in the environment.

For the evaluation of the pest management alternatives portion, staff assembled 44 abstracts for copper and 683 for tributyltin. As the alternatives portion was completed, a growing list of contacts contributed even more material. Staff also sent out requests for additional literature to interested parties, including managers of POTWs, County Agricultural Commissioners, University of California Cooperative Extension Horticultural Advisors, and registrants of copper and tributyltin containing pesticidal products.

Identifying sites where copper and tributyltin containing pesticides are used

Staff identified sites where copper and tributyltin containing pesticides are used (e.g., sewers, drains, cooling water systems), and used the sites to search DPR's Pesticide Label Database (PLD) for product labels of copper and tributyltin containing pesticides and alternatives that do not contain these compounds. This component was essential to verify products currently registered in California that are specifically used for the identified sites. In addition to gathering product labels and interviewing arborists, public works engineers, and managers of cooling water systems, the pest management team compiled a comprehensive list of copper and tributyltin alternatives. The alternatives to copper are divided into municipal and residential use categories; within these categories, they are further described by duration of effectiveness, major limitations, and approximate cost (Part Four). The analysis prepared for tributyltin describes tributyltin substitutes; lists specific products registered in California; describes limitations of each class of alternative; and provides cost ranges for treatment, maintenance, and cleanup for each product (Part Five).

Administrative options for regulating copper and tributyltin containing compounds

Options include promoting a voluntary program among users of copper and tributyltin containing products or employing one of three regulatory options (Part Six). These options include 1) canceling copper and tributyltin containing products throughout California without regard to regionally specific discharge problems, 2) designating the products as restricted materials to prevent non-licensed users from purchasing and using them, and 3) prohibiting sale and use of the products on a regional basis. This report will provide the basis for a decision to proceed with one of the three options.

Establishing Water Quality Objectives

Water quality objectives are established by the State Board, which evaluates scientific studies of the effects of contaminants on organisms and biological communities (SFBRWQCB, 1992a). Effluent limitations based on water quality objectives are then established for discharges from POTWs; effluent limitations are based on the depth of the water body where the discharge leaves the POTW. If effluents violate conditions of discharge permits, the Regional Board could fine POTWs up to $25,000 per day.

Water quality objectives for copper

In 1986, Region 2 adopted amendments revising the Water Quality Control Plan for the San Francisco Bay Basin (Basin Plan). This version of the Basin Plan was rescinded in September 1994 and is currently under revision. One amendment included a site-specific water quality objective for copper in the San Francisco Bay. Region 2 received funding from the State Board and the United States Environmental Protection Agency to develop the site-specific objectives for shallow- and deep-water effluent limitations (discharges from POTWs). In October 1992, Region 2 adopted a site-specific water quality objective for total copper in San Francisco Bay of 4.9 micrograms per liter (ug/L) (= parts per billion [ppb]) based on the protection of aquatic life (SFBRWQCB, 1992b). This amendment to the Basin Plan (Resolution 92-128) adopted a deep-water effluent limitation of 37 ug/L, and a 4.9 ug/L limitation for shallow-water discharges. Because concentrations of copper higher than 4.9 ug/L were measured through most of the estuary, Resolution 92-128 established goals for reducing mass emissions of copper by the year 2003 of 20 percent for storm water, and 25 percent for riverine sources and municipal and industrial discharges.

A later amendment (Resolution 93Ð61) to the Basin Plan established a mass-based approach to determine copper loading for the San Francisco Bay (SFBRWQCB, 1993). Because copper levels exceeded mass-loading limitations throughout the South Bay, one POTW, Palo Alto RWQCP, which discharges to shallow water, was told to reduce its copper load by 32 percent. (The load reduction for the two other shallow-water dischargers, San Jose and Sunnyvale, remained at 25 percent.) In annual mass loading, this is equivalent to 720 pounds, 32 percent less than the 1,060 pound baseline discharge.

In 1993, Region 2 issued a Cease and Desist Order (CDO) to the Palo Alto RWQCP upon renewal of its NPDES permit because violations of the new copper discharge limitations were anticipated. The CDO set up a three-year schedule for compliance with the mass limit and a five-year schedule for concentration limit compliance for Palo Alto and similar schedules for San Jose and Sunnyvale. The conditions of the CDO generated a comprehensive outreach program targeted toward public, commercial, and industrial sectors.

Water quality objectives for tributyltin

In 1992, Region 2 adopted a shallow-water effluent limitation for tributyltin of 5 parts per trillion (ppt) (=0.005 ug/L) for the San Francisco Bay. In studies conducted by the State Board in the late 1980s, high levels of organic tin compounds (butyltins) were found in river and lake marinas (see Part Three, this report). The high concentrations of butyltins were attributed to the use of tributyltin-containing antifouling hull paints on boats.

From 1992 to 1994, samples from discharges in Palo Alto (RWQCP) exceeded the effluent limit of tributyltin (Kelly D. Moran, pers. comm.). Staff of the Palo Alto RWQCP searched for various tributyltin sources and ruled out antifouling hull paints. They found that tributyltin-containing discharge from cooling water systems was the most obvious source in their service areas (RWQCP, 1993; RWQCP, 1994).

Sources of copper and tributyltin for South Bay POTWs

Loading of metals for the three POTWs that discharge south of the Dumbarton Bridge (Palo Alto, San Jose, and Sunnyvale) is exacerbated by the shallow water and slow replenishment of fresh water in the South Bay (Lacy, 1993). Sources of copper from municipal and industrial discharge in the South Bay make up 25% of the annual average loading of copper. Sources of copper discharge via sewers, storm drains, and rivers include abandoned mines, drinking water pipes, brake linings, copper-containing root control compounds, human wastes, food wastes, and laundry graywater (Larry Walker Associates, 1994). The Palo Alto RWQCP monitored residential, industrial, and commercial wastewater to establish the source of metals in their effluent (RWQCP, 1994). They also studied specific discharge sources, such as machine shops, vehicle service facilities, and cooling towers.

Two studies identified copper sulfate root control compounds as contributing three to ten percent of copper recovered in the effluent of POTWs (Larry Walker Associates, 1994; SRI International, 1991). In Martinez, the Central Contra Costa Sanitary District (CCCSD) initiated a research and implementation project to identify and quantify sources of trace metals in residential wastewater (Larry Walker Associates, 1994). The study found that of all metals evaluated, copper should be given high priority for control, and residential source control efforts should focus on reducing use of copper-containing root control compounds. In Palo Alto, residential use of copper sulfate for tree roots in 1990 accounted for 36 to 42 pounds of elemental copper, approximately 10 percent of the total copper loading (SRI International, 1991).

Unlike copper, potential sources of tributyltin are entirely pesticidal. They include biocidal cooling water systems additives, antifouling paints and stains, protective wood treatments, disinfectant commercial toilet bowl cleaners, and disinfectant carpet and upholstery cleaners (Department of Pesticide Regulation, 1993). In Palo Alto, RWQCP staff determined from surveys that the lack of boat maintenance facilities and tributyltin-containing paints or disinfectants pointed to cooling water systems as the single source of tributyltin (Moran, 1994). Staff calculated that one gallon of 2 percent tributyltin solution discharged to the sewer and treated with other wastewater at the RWQCP would contaminate more than 2.4 billion gallons of the effluent, exceeding the 5 ppt tributyltin effluent limitation. Even very small discharges from one or two cooling towers using tributyltin-containing products could put the City of Palo Alto in violation of their discharge permit (Moran, 1994).

Existing local programs for reducing sources of copper and tributyltin

Educational outreach to limit discharges of copper and tributyltin

Since 1990, Palo Alto RWQCP has conducted an aggressive pollution prevention program to comply with discharge limits. Their Clean Bay Business program recognizes local plumbers no longer using copper sulfate for root control, and hardware stores that cooperate by voluntarily not selling these products. RWQCP staff also published a list of auto shops that adopted environmentally sound practices. As of February 1994, RWQCP had published four technical documents on best management practices (BMPs); four user-friendly booklets on BMPs; 11 technical reports; 16 public relations items (including flyers, coupons, door hangers, and buttons); and 40 fact sheets. Only some of these address copper-containing root control compounds, but most deal with the idea of source reduction. As a result of the plant's outreach efforts, cooperation of area businesses and residents, and improved copper-removal efficiency the average annual effluent copper concentration has decreased from 150 ug/L in 1979 to approximately 10 ug/L in 1993. RWQCP's regulatory programs currently address the sewer and storm water discharges of approximately 85 major industrial facilities and more than 1,000 commercial businesses.

The RWQCP created the Cooling Water Systems Program in 1992 to collect information about cooling water systems, develop and promote BMPs for operating and maintaining cooling water systems, and distribute the BMPs to cooling tower users within RWQCP's service area (RWQCP, 1994a). Participants in the program held several public meetings to request input from the regulated community and treatment chemical suppliers. In 1993, the RWQCP developed BMPs that promote appropriate operation and maintenance of cooling water systems to reduce the amount of metals discharged into the Bay while also lowering cooling system costs.

Other governmental agencies in the San Francisco Bay Area besides the Palo Alto RWQCP have published educational material on proper disposal of toxics, some with an emphasis on root control and cooling water systems (San Francisco Bay Area Pollution Prevention Group, 1994). Examples include the City of San Jose Environmental Services Department, the City and County of San Francisco Department of Public Works, Central Contra Costa Sanitary District, and the Sunnyvale Water Pollution Control Plant. A brochure on copper sulfate root killers was developed in April 1994 by 25 Bay Area POTWs and distributed to over 200,000 households throughout the region.

Local ordinances imposed by the cities of Palo Alto and San Jose

Advocates of outreach programs have complained that the task of reducing the amount of metals entering municipal sewers is monumental because effluent limitations are so low on the level of parts per billion or trillion. For example, the Palo Alto RWQCP calculated that the small volume of tributyltin-containing discharge that causes the plant to violate its effluent limitation makes it impractical to identify and eliminate all the small sources of tributyltin through an inspection and education program (Moran, 1994a).

In response to continued violations of effluent limitations, the City of Palo Alto passed an ordinance in February 1992 that banned the discharge of copper-containing root control compounds containing greater than five percent copper by weight to the sanitary and storm sewer systems. The RWQCP found that banning discharge rather than sale of these products made enforcement of the ordinance difficult; although monitoring the sale of products from retail outlets and plumbers is achievable, monitoring the discharge of copper-based root killers from every household is impossible. RWQCP recognized a loophole with their outreach program when the owner of a chain retail outlet in their service area chose not to participate in a local-government sponsored program until getting more information from his parent company or professional association (Moran, 1994b).

Following Palo Alto's example, San Jose adopted an ordinance in September 1992 that regulated the sale, use, and discharge of copper-containing root control compounds. San Jose City Council supported the ordinance based on state and federal laws that they believed stated that the City may exercise control over users of its storm drain and sewer systems, and may adopt regulations relating to all substances discharged into these systems, including pesticides. DPR responded that authority to regulate pesticides resides with DPR, pursuant to Food and Agricultural Code 11501.1, which states that no ordinance or regulation of local government, including, but not limited to, an action by a city council may prohibit or in any way attempt to regulate any matter relating to the registration, sale, transportation, or use of economic poisons, and any of these ordinances, laws, or regulations are void and of no force or effect. Only county agricultural commissioners are authorized to regulate pesticides locally under the supervision and control of DPR. City councils and county boards of supervisors are not permitted to adopt regulations (Food and Agricultural Code 11501.1). DPR took the position that both ordinances passed by Palo Alto and San Jose were invalid based on section 11501.1.

Despite good intentions to comply with effluent limitations, POTWs will increasingly face the same dilemma: compliance by imposing local ordinances to reduce loading of toxics, or support of legislation that will prohibit the use of offending toxics in their service area. With the implementation of a successful copper and tributyltin program, local governmental agencies will be able to rely on DPR to provide thorough research on the issue, perform an alternatives analysis, and offer a workable administrative solution to the problem.


Department of Pesticide Regulation. 1994. Letter to Assembly Member Byron D. Sher from Director James W. Wells, August 5, 1994.

Department of Pesticide Regulation. 1993. Pesticide Label Database. DPR, Sacramento, CA.

Department of Pesticide Regulation. 1992. Letter to Susan Hammer, Mayor, City of San Jose, from Director James W. Wells, October 14, 1992.

Lacy, J. 1993. Wasteload allocation for copper for San Francisco Bay. Final Staff Report. California Regional Water Quality Control Board, San Francisco Bay Region, Oakland, CA.

Larry Walker Associates. 1994 Residential metals study. Prepared for the Central Contra Costa Sanitary District, Martinez, CA.

Moran, K.D. 1994a. Why tributyltin cooling additives cause compliance problems for the Palo Alto Regional Water Quality Control Plant. Memorandum to Nita Davidson. Regional Water Quality Control Plant, City of Palo Alto.

Moran, K.D. 1994b. Copper-based root killers. Memorandum to Nita Davidson. Regional Water Quality Control Plant, City of Palo Alto.

RWQCP. 1994a. Cooling water systems source control program. Fact Sheet. City of Palo Alto. Palo Alto Regional Water Quality Control Plant.

RWQCP. 1994b. Clean Bay Plan 1994. Report. City of Palo Alto. Palo Alto Regional Water Quality Control Plant.

RWQCP. 1993. Special sampling technical report Palo Alto Regional Water Quality Control Plant. Memorandum from William D. Miks, Manager Water Quality Control to Steve Ritchie, Executive Officer, California Regional Water Quality Control Board, San Francisco Bay Region, July 8, 1993.

San Francisco Bay Area Pollution Prevention Group. 1994. Copper levels in wastewater: source identification and control strategies. Results of the Bay Area Pollution Prevention Group Copper Issues Survey, 1994.

SFBRWQCB. 1992a. Proposed amendment to the Water Quality Control Plan Hearing to receive testimony and consider a site-specific copper objective for San Francisco Bay (Memorandum). Executive Officer Summary Report, September 16, 1992. California Regional Water Quality Control Board, San Francisco Bay Region.

SFBRWQCB. 1992b. Adopting an amendment to the Water Quality Control Plan and requesting approval from the State Water Resources Control Board. Resolution No. 92-128, October 21, 1992. California Regional Water Quality Control Board, San Francisco Bay Region.

SFBRWQCB. 1993. Adopting an amendment to the Water Quality Control Plan: establishing a wasteload allocation for copper for San Francisco Bay and requesting approval from the State Water Resources Control Board. Resolution No. 93-61, June 16, 1993. California Regional Water Quality Control Board, San Francisco Bay Region.

U.S. EPA. 1984. Ambient aquatic life water quality criteria for copper. U.S. Environmental Protection Agency, Office of Research and Development, Environmental Research Laboratories, Duluth, MN and Narragansett, RI.