Step 2: Identify habitats

product of this step is a written description of the proposed dredged material

management activity.

Example 1: Description of the Dredged Material Management Activity

A local marina has proposed dredging 10 new slips. The existing water depths at the slips is 1.5 m (5 ft)

mean lower low water (MLLW). Each slip will be 15 6 m (50 20 ft) and dredged to a depth of 3 m

(10 ft) MLLW with a 0.6-m (2-ft) over-dredge allowance. The project will also require dredging of the

channel resulting in an estimated 76,460 cu m (100,000 cu yd) of dredged material. A clamshell dredge

will remove the material to a hopper barge for transport to an offshore unconfined management area for

which a site designation report is available. The water depth near the site averages 30 m (100 ft), and

there is low to moderate wave energy.

Step 2: Identify habitats

It is important to identify habitats in and near the dredged material management

area, because these will largely determine human uses and ecological receptors for

the conceptual model. The identifications should be specific and conform to

common ecological descriptions of aquatic habitat.

There is no restriction or recommendation regarding the number of habitats

described in this section. Generally, the habitat classifications should not be so

broad as to lose ecological meaning, nor so specific that they lack information

regarding the relationships among organisms. Example 2 provides a list of the types

of questions to ask during this step.

There are no rules regarding how close to a management area a habitat must be

to be included in the site description. It is best to use biological or physical

characteristics that impose a functional, as opposed to a geographic relationship

between the management area and appropriate habitats to make decisions. Such

characteristics might include: depth of vertical mixing, the presence of geological

sills, a permanent thermocline, erosional characteristics, water mass mixing, wave

action, grain size, flow, presence of a continuous shellfish bed, similarity in

vegetative characteristics, etc. The product of this step should be narrative text,

maps, and figures, as necessary, which describe the habitats at and adjacent to the

disposal site. Much of this information should be available from the site designation

process and NEPA documentation.

Chapter 2 Problem Formulation