40466 



Federal Register / Vol. 56. No. 157 / Wednesday, August 14, 1991 / Proposed Rules 



Appendix 3. Intermediate-level Onsite 

 Determination Method 



On occasion, a more rigorous 

 sampling method is required than the 

 routine method to determine whether 

 hydrophytic vegetation is present at a 

 given site, especially where the 

 boundary between wetland and 

 nonwetland is gradual or indistinct. This 

 circumstance requires more intensive 

 sampling of vegetation, soUs, and 

 hydrology than presented in the routine 

 determination method. This method also 

 may be used for areas greater than five 

 acres in size or other areas that are 

 highly diverse in vegetation. 



The intermediate-level onsite 

 determination method has been 

 developed to provide for more intensive 

 vegetation sampling than the routine 

 method. Two optional approaches are 

 presented: (1) Quadrat transect sampling 

 procedure, and (2) vegetation unit 

 sampling procedure. The former 

 procedure involves establishing 

 transects within the project area and 

 sampling plant communities along the 

 transect within sample quadrats, with 

 soils and hydrology also assessed in 

 each sample plot. In contrast, the 

 vegetation unit sampling procedure 

 offers a different approach for analyzing 

 the vegetation. First, vegetation units are 

 designated in the project area and then 

 a meander survey is conducted in each 

 unit where visual estimates of percent 

 areal coverage by plant species are 

 made. Soil and hydrology observations 

 also are made. Boundaries between 

 wetland and nonwetland are 

 established by examining the 

 transitional gradient between them. 



The following steps should be 

 completed: 



Step 1. Locate the limits of the project 

 area in the field and conduct a general 

 reconnaissance of the area. Previously 

 the project boundary should have been 

 determined on aerial photos or maps. 

 Now appropriate ground reference 

 points need to be located to insxire that 

 sampling will be conducted in the proper 

 area. In examining the project area, 

 were any significandy disturbed areas 

 observed? If YES. identify their limits for 

 they should be evaluated separately for 

 wetland determination purposes 

 (usually after evaluating imdisturbed 

 areas). Refer to the section on disttirbed 

 areas to evaluate the altered 

 characteri3tic(s) (i.e.. vegetation, soils, 

 or hydrology); then return to this method 

 to continue evaluating the 

 characteristics not altered. Keep in mind 

 that if at any time during this 

 determination, one or more of these 

 three characteristics is foimd to have 

 been significantly altered, the disturbed 



areas procedures should be followed. If 

 the area is not significantly disturbed, 

 proceed with Step 2. 



Step 2. Decide how to analyze plant 

 commimities within the project area: (1) 

 By selecting representative plant 

 communities (vegetation units), or (2) by 

 sampling along a transect Discrete 

 vegetation units may be identified on 

 aerial photographs, topographic and 

 other maps, and/or by field inspection. 

 These units will be evaluated for 

 hydrophytic vegetation and also for 

 hydric soils and wetland hydrology. If 

 the vegetation unit approach is selected, 

 proceed to Step 3. An alternative 

 approach is to establish transects for 

 identifying plant communities, sampling 

 vegetation and evaluating other criteria, 

 as appropriate. If the transect approach 

 is chosen, proceed to Step 4. 



Step 3. Identifying vegetation units for 

 sampling. Vegetation units are identified 

 by examining aerial photographs, 

 topographic maps. NWI maps, or other 

 materials or. by direct field inspection. 

 All of the different vegetation units 

 present in the project area shouJd be 

 identified. The subject area should be 

 traversed and different vegetation units 

 specifically located prior to conducting 

 the sampling. 



Field inspection may refine previously 

 identified vegetation units, as 

 appropriate. It may be advisable to 

 divide large vegetation units into- 

 subimits for independent analysis. 



(Caution: In highly variable terrain, such as 

 ridge and swale complexes, be sure to 

 stratify properiy.) Decide which plant 

 community to sample first and proceed to 

 Step 7. 



Step 4. Establish a baseline for 

 locating sampling transects. Select as a 

 baseline one project boundary or a 

 conspicuous feature, such as road, in the 

 project area. The baseline should be 

 more or less parallel to the major 

 watercourse through the area, if present, 

 or perpendicular to the hydrologic 

 gradient. Determine the approximate 

 baseline length. Proceed to Step 5. 



Step 5. Determine the minimum 

 number and position of transects. Use 

 the following to determine the minimum 

 number and position of transects 

 (specific site conditions may necessitate 

 changes in intervals or additional 

 transects). Divide the baseline length by 

 the nxmiber of required transects to 

 establish baseline segments for 

 sampling. Establish one transect in each 

 resulting baseline segment. Use the 

 midpoint of each baseline segment as a 

 transect starting point. For example, if 

 the baseline is 1,200 feet in length, three 

 transects would be established: one at 

 200 feet, one at 600 feet, and one at 1.000 

 feet from the baseline starting point. 



Make sure that all plant community 

 types are included within the transects; 

 this may necessitate relocation of one or 

 more transects lines or establishing 

 more transects. Each transect should (^ 

 extend perpendicular to the baseline. 

 Once positions of transect lines are 

 established, go to the beginning of the 

 first transect and proceed to Step 6. 



Step 6. Locate sample plots along the 

 transect. Along each transect, sample 

 plots are established v^thin each plant 

 community encountered to assess 

 vegetation, soils, and hydrology. When 

 identifying these sample plots, two 

 approaches may be followed: (1) Walk 

 the entire length of the transect, taking 

 note of the number, type, and location of 

 plant commimities present (flag the 

 location, if necessary), and on the way 

 back to the baseline, identify plots and 

 perform sampling, or (2) identify plant 

 communities as the transect is walked 

 and sample the plot at that time 

 ("sample as you go"). The sample plot 

 should be located so it is representative 

 of the plant commimity type. When the 

 plant community type is large and 

 covers a significant distance along the 

 transect, select an area that is no closer 

 than 300 feet to a perceptible change in 

 plant community type; mark the center 

 of this area on the base map or photo 

 and flag the location in the field, if 

 necessary. f 



(Caution: In highly variable terrain, such as 

 ridge and swale complexes, be sure to 

 stratify properly to ensure best results.) 



At each plant community, proceed to 

 Step 7. 

 Step 7. Consider the following: 



(1) Is the area presently lacking 

 hydrophytic vegetation or hydrologic 

 indicators due to aimual. seasonal, or 

 long-term fluctuations in precipitation, 

 surface water, or ground-water levels? 



(2) Are hydrophytic vegetation 

 indicators lacking due to seasonal 

 fluctuations in temperature (e.g^ 

 seasonality of plant growth)? 



If the answer to either of these 

 questions is YES or uncertain, and the 

 area meets the description of one of the 

 exceptions to the three criteria, proceed 

 to the appropriate section of this 

 manual. If the answer to both questions 

 is no, proceed to Step 8. 



(Note: In some cases, normal climatic 

 conditions, such as snow cover or frozen 

 soils, may prevent an accurate assessment of 

 the wetland criteria: one must use best 

 professional judgment to determine if 

 delaying the wetland delineation is 

 appropriate.) 



Step 8. Characterize the vegetation of 

 the vegetation unit or the plant 

 community along the transect. 



f 



