California Rapid Assessment Method for Wetlands - State Water ...

California Rapid Assessment Method for Wetlands v. 5.0.2 – Chapter 4
B. Rationale: A wider buffer has a greater capacity to serve as habitat for wetland edgedependent
species, to reduce the inputs of non-point source contaminants, to control erosion,
and to generally protect the wetland from human activities. Also see the buffer rationale
presented in Section 4.1.2 above.
C. Seasonality: This metric is not sensitive to seasonality.
D. Office and Field Indicators: This procedure can be performed initially in the office using
the site imagery, and then revised based on the field visit. The procedure has four steps as
presented in Table 4.6 below. There are special considerations for riverine wetlands explained
below in Figure 4.4.
Table 4.6: Steps to estimate Buffer Width for all wetlands except Riverine, for
which these steps are modified according to Figure 4.4.
Step 1
Step 2
Step 3
Step 4
Identify areas in which open water is within 5 m of the AA. These areas are
excluded from buffer calculations.
Draw straight lines 250 m in length perpendicular to the AA through the
buffer area at regular intervals along the portion of the perimeter of the AA
that has a buffer. For one-sided riverine AAs, draw four lines; for all other
wetland types, draw eight lines (see Figures 4.3 and 4.4 below).
Estimate the buffer width of each of the lines as they extend away from the
AA. Record these lengths on the worksheet below.
Estimate the average buffer width and record it on the worksheet below.
Upland Buffer
Development
Open Water
Assessment Area
Highway or Parking Lot
Other Wetland
A
H
A
B
B
A
B
G
C
G
H
F
E
C
D
F
E
D
Figure 4.3: Examples of method used to estimate Buffer Width. It is based on the lengths
of eight lines A-H that extend at regular intervals though the buffer areas,
whether they are not extensive (A) or all encompassing (B).
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