Leaching: The removal of salts and trace elements from soil by the downward percolation of water. (SFEP 2007)

Leadership in Energy and Environmental Design (LEED): A rating system developed by the U.S. Green Building Council to certify buildings with sustainable features.

Level of Service (LOS): A measure by which transportation planners reckon the quality of service on transportation devices or roadway and intersection operations.

Light pollution: Excessive or obtrusive artificial outdoor night lighting.

Limited (with respects to quantity, quality, biodiversity): Refers to areas of sparse vegetation and areas where natural vegetation is broken up by larger areas of open or barren ground.

Liquefaction: A process by which water saturated granular soils transform from a solid to a liquid state due to ground shaking. This phenomenon usually results from shaking from energy waves released in an earthquake.

Local Agency Formation Commission (LAFCO): The five commission within San Mateo County that reviews and evaluates, and is empowered to approve, disapprove, or conditionally approve all proposals for formation or changes in boundaries of special districts and cities, annexation to special districts or cities, consolidation of districts, and merger of districts with cities. Each county's LAFCO is such proposals.

Local Street: A street providing direct access to properties and not designed for through traffic.

Lot: A legally recognized parcel of land abutting on one or more public or City approved private streets. (City of Redwood City, Redwood City General Plan)

Low Impact Development (LID): An approach to land development that uses various land planning and design practices and technologies to simultaneously conserve and protect natural resource systems and reduce infrastructure costs. LID is intended to provide for  land development in a cost- effective manner that helps mitigate potential environmental impacts. Typically, emphasis is on employing natural and constructed features that reduce the rate of stormwater runoff, filter out pollutants, facilitate stormwater storage onsite, infiltrate stormwater into the ground to replenish groundwater supplies, or improve the quality of receiving groundwater and surface water.

Marsh: A common term applied to describe treeless wetlands characterized by shallow water and abundant emergent, floating, and submerged wetland flora. Typically found in shallow basins, on lake margins, along low gradient rivers, and in calm tidal areas. Marshes may be fresh, brackish or saline, depending on their water source(s).

Mean: Midpoint between high and low.