4.1A – Marina Siting and Design – Flushing Management

Management Measure

Site and design new and expanding marinas such that tides and/or currents will aid in flushing the site or renew its water regularly.

New or expanding marinas should be designed such that the natural circulation of water from tidal action is not restricted. Ensure that the bottom of the marina and entrance channels are not deeper than adjacent navigable channels to help keep the bottom of the marina basin from becoming a pollutant trap, leading to low dissolved oxygen levels. Consider alternatives to a single-entrance design in poorly flushed water bodies to enhance flushing, for example: An open design instead of a semi-enclosed design in a naturally protected location and wave attenuators instead of fixed breakwaters where they will provide sufficient protection.
New marinas should be designed with as few enclosed water sections or separated basins as possible to promote circulation within the entire basin. Small side basins off the main basin may not flush nearly as well as a large single basin. Consider the value of entrance channels in promoting flushing when designing or reconfiguring a marina. Two entrances at opposite ends of a marina can promote flow-through currents.
Use mechanical aerators to improve flushing and water quality where basin and entrance channel configuration cannot provide adequate flushing. Place them in basin corners or other poorly flushed areas.

California Department of Boating and Waterways provides a variety of grants and loans to assist in the infrastructure development of private and public boat launching facilities and marinas.

USEPA. 2001. National Management Measures Guidance to Control Nonpoint Source Pollution from Marinas and Recreational Boating. EPA 841-B-01-005. U.S. Environmental Protection Agency, Washington, DC. Downloaded on March 16, 2008