Rhode Island Code of Regulations
Title 650 - Coastal Resources Management Council
Chapter 20 - Coastal Management Program
Subchapter 00 - N/A
Part 9 - Rules and Regulations Governing the Protection and Management of Freshwater Wetlands in the Vicinity of the Coast
Section 650-RICR-20-00-9.21 - Specific Criteria for Identifying Freshwater Wetland and Floodplain Edges

1. Those typical plant species listed in R.I. Gen. Laws §§ 2-1-20(3)"bog", (10) "marsh" and (16) "swamp"; or

2. Those plant species listed as having a wetland indicator status of obligate (OBL) according to the most recent edition of the National Wetland Plant List: State of Rhode Island Wetland Plant List, as prepared by the U.S. Army Corps of Engineers; or

3. Those plant species listed as having a wetland indicator status of facultative wetland (FACW), facultative (FAC) or facultative upland (FACU) according to the National Wetland Plant List: State of Rhode Island, where such plants are present along with other clear hydrologic indicators of wetland.

1. Morphologic features or properties associated with hydric soils in accordance with the most recent version of the Field Indicators for Identifying Hydric Soils in New England.

2. Visual observation of soil saturation within twelve inches (12") of the soil surface (considering both seasonal and recent weather conditions);

3. Distinct water marks on vegetation or other fixed objects;

4. Sulfitic materials (H2S - rotten egg odor) within twelve inches (12") of the soil surface;

5. Mound and pool microtopography;

6. Patches of peat mosses (Sphagnum spp.)

7. Soil morphologic evidence of recent or periodic flooding (e.g., stratification associated with flood plains);

8. Visual observation of surface inundation (considering both seasonal and recent weather conditions);

9. Dark or water-stained leaves on the ground surface;

10. Drift or wrack lines of water-borne materials;

11. Wetland drainage features or patterns such as scoured channels;

12. Morphological plant adaptations (e.g., buttressed trees trunks, adventitious roots, exposed or shallow root systems);

13. Distinct or prominent pore linings (oxidized rhizopheres) along live roots within twelve inches (12") of the soil surface.

1. The use of this methodology is intended to facilitate the location and identification of the edge of "vegetated" freshwater wetlands, but must not be interpreted as redefining freshwater wetlands regulated under the Act and these Rules.

2. All edge locations and delineations are subject to the CRMC's review and acceptance under the procedures set forth in § 9.9.2 of this Part for requests to determine the presence of jurisdictional area. Accordingly, all requests to verify the edge of these types of freshwater wetlands will require on-site inspection and analysis.

3. Areas discovered during the delineation of freshwater wetlands which appear to have altered conditions (e.g., removal of vegetation, ditching, draining, filling or other alterations that have changed or appear to change normal conditions) must be documented.

1. The edge of rivers, streams, intermittent streams, ponds, vernal pools, areas subject to storm flowage, areas subject to flooding and other areas dominated by open or flowing water shall be the ordinary high water mark of standing or flowing water. The ordinary high water mark is the line separating land flooded at high water and land exposed at high water. This line may be determined and documented by using recorded hydrologic data (e.g., data obtained from site specific planning and design documents; in-stream flow studies; stream gauge data; the CRMC's file data; or flood data), or, in the absence of these, by observing physical characteristics, such as evidence of a clear demarcation line between terrestrial and aquatic conditions as a result of standing or flowing water; shelving; permanent watermarks and stains on woody vegetation or other fixed objects, such as bridges, stones, walls, docks, or piers; changes in the character of the soil; the presence of water-borne natural litter and debris; evidence of surface scouring; or other appropriate means.

2. The edge of any pond and incoming or outgoing flowing body of water shall be that location where characteristics associated with a lentic ecosystem and a lotic ecosystem are both present.

1. Calculation of one hundred (100) year flood discharge based on a one hundred (100) year rainfall event identified in the Stormwater Management, Design, and Installation Rules, 250-RICR- 150-10-8, and a generally accepted hydrologic model including, but not limited to, TR-20, TR-55 or commercially available software based on TR-20 or TR-55. In certain cases involving very large watersheds an acceptable regression equation methodology may be used, such as a USGS regression for Rhode Island; and

2. Using the flood discharge established above in § 9.21(C)(1) of this Part, along with detailed topography mapping, prepare a determination of peak one hundred (100) year flood elevation using a widely accepted hydraulic model such as the U.S. Army Corps of Engineers' Hydrologic Engineering Center River Analysis System (HEC-RAS). Once this elevation is established the edge of the one hundred (100) year floodplain must be plotted on a detailed site topography map.

1. Where FEMA has designated a floodway for any river or stream on a FEMA Flood Insurance Rate Map (FIRM), the CRMC will recognize the same floodway; or

2. Where no FEMA floodway has been established for a river or stream, the edge of the channel as identified in § 9.21(A) of this Part shall also be considered the edge of the floodway.

1. The CRMC may compile designated riverbank widths (one hundred feet (100') or two hundred feet (200')) for flowing water body segments and maintain this information on file. Such designations shall be based upon currently available maps, aerial photographs, observations, and past determinations by the CRMC. All applicants may consult with the CRMC regarding the availability of designated riverbank widths along any flowing bodies of water segments in the project area. If a riverbank width has been determined by the CRMC, this designation can be used to preclude the need for the applicant to undertake field measurements or observations.

2. When designated riverbank widths are not available, the identification and assignment of a riverbank width shall, if the width is not obvious, be conducted using the following method, without regard to topography:

3. The arithmetic average or mean of the channel width measurements shall serve as the average channel width for the purposes of assigning riverbank. The mean shall be calculated using the formula:

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where "X" equals each channel width measurement and "n" equals the number of measurements.

4. When the mean channel width is less than ten feet (10'), the riverbank shall be one hundred feet (100'). When the mean channel width is ten feet (10') or more, the riverbank shall be two hundred feet (200').