Introduction

Beginning with the Federal Water Pollution Control Act of 1948, there has been a progression of laws intended to regulate the discharge of pollutants into the waters of the United States. The growing public awareness and concern for improving water quality resulted in a series of amendments in 1972, 1977, and 1987. This law and subsequent amendments collectively became known as the Clean Water Act (CWA). The authority for enforcement of the CWA rests with the U.S. Environmental Protection Agency (EPA). In 1969 the Porter-Cologne Act gave ultimate jurisdiction of water rights and water quality in California to the State Water Resources Control Board. Nine Regional Water Quality Control Boards provide local control, including enforcing water quality standards, and taking whatever action may be needed to maintain those standards.

Background

In an effort to reduce non-point source pollution carried by stormwater and urban runoff, State water quality regulations and standards now require that all new development or significant redevelopment projects over 5,000 square feet, whether they are residential, industrial, commercial or municipal, implement Best Management Practices or BMPs. These practices are intended to be effective and practicable measures (including technological, educational, and institutional considerations) for reducing the amount of water pollution generated by non-point sources.

A stormwater BMP can be “any program, technology, process, siting criteria, operating method, measure, or device, which controls, prevents, removes, or reduces pollution” (California Stormwater Quality Association Handbook).

Structural stormwater BMPs are engineered systems designed to improve the quality of runoff and, depending on application, may also provide flood control and down-stream erosion control. These devices can be built to mitigate any number of target pollutants, including trash, suspended sediments, nutrients, oils, and grease. For example, certain BMPs employ natural methods of water purification through the use of constructed wetlands, vegetated swales, and infiltration basins. An unintended consequence of BMP implementation is the potential for vector production (e.g. mosquitoes, flies, and rodents), which is frequently associated with sheltered habitats and standing water. Unless designed and maintained properly, standing water may remain in BMPs long enough to provide conditions that will allow production of mosquitoes (Metzger, 2004).

Due to the potential of stormwater BMPs to produce mosquitoes, it is important that agencies responsible for vector control be aware of the locations and types of existing and planned installations. Currently, these breeding sources are often reported to vector control agencies by the public only after they have become a nuisance and public health hazard. Vector control agencies under the authority of the California Health and Safety Code (Sec. 2040) have the obligation and authority to require “the person or agency claiming ownership” to remove conditions that contribute to mosquito production (California Health and Safety Code Sec. 2060). Some stormwater BMPs are less likely to produce mosquitoes than others, depending on the structural design and on surrounding conditions. Larger urban developments can contain dozens of BMPs. Involving vector control agencies early in the planning process would assure that the most effective options were implemented. This proactive approach would save developers and property owners the cost of having to make required changes after the BMP was in place.

Structural stormwater BMPs require proper and timely maintenance to ensure they meet water quality objectives and minimize potential for mosquito and vector production. Frequently, there is no provision or long-term funding for the ongoing maintenance of BMPs following installation. To complicate matters, there is often confusion about ownership and responsibilities. Neglecting maintenance for too long a period can result in poor BMP performance and often results in areas of standing water due to accumulations of captured materials and vegetation overgrowth. These conditions favor production of mosquitoes and other vectors such as rats. Under certain circumstances, neglected BMPs may eventually be viewed as providing “habitat” for certain species of animals. If this occurs, any subsequent maintenance procedures may be in violation of some other state or federal statute. It is not uncommon for the party responsible for the BMP to be in violation of the Health and Safety Code because of mosquito production, and facing a violation of the Endangered Species Act (ESA) if they take the steps necessary to curtail mosquito production.