Compatibility, Land Use: The characteristics of different uses or activities that permit them to be located near each other in harmony and without conflict. Some elements affecting compatibility include: intensity of occupancy as measured by dwelling units per acre; pedestrian or vehicular traffic generated; volume of goods handled; and such environmental effects as noise, vibration, glare, air pollution, or the presence of hazardous materials.

Composting: The controlled microbial decomposition of organic matter (such as food scraps and yard trimmings) in the presence of oxygen into a humus or soil-like material.

Congestion Management Plan (CMP): A state-mandated program (Government Code

§65089a) that requires each county to prepare a plan to relieve congestion and reduce air pollution. References to “the” Congestion Management Plan are to the CMP adopted by C/CAG for San Mateo County.

Conservation: The management of natural resources to prevent waste, destruction, or neglect.

Constituent of concern: A hazardous material that has the potential to cause damage to human health or the environment, and create a “risk” to human health and the environment.

Contamination: An impairment of the quality of (1) surface or ground water or (2) soils that creates a hazard to the public health through poisoning or through the spread of disease.

Contour: An imaginary line of constant elevation on the ground surface. The corresponding line on a map is called a “contour line.”

Creek: Natural stream of water smaller than a river.

Criteria: Standards, rules, or tests on which a judgment or decision may be based.

Criteria air pollutant: The gaseous monitored to demonstrate attainment or non- attainment of national and state ambient air quality standards. Criteria air pollutants include carbon monoxide, nitrogen dioxide, ozone, and sulfur dioxide. Monitoring is performed.

Cross-contamination: Detrimental effects on an ecosystem caused by the movement of contaminants or pollutants from one area of the environment to another due to invasive subsurface activities.

Cumulative Effects: The combined environmental impacts that accrue over time and space from a series of similar or related individual actions, contaminants, or projects. Although each action may seem to have a negligible impact, the combined effect can be significant.

Day Night Average Sound Level (DNL): Adopted by the U.S. Environmental Protection Agency for measurement of environmental noise, DNL represents the average daytime