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Wetland Critical Areas - Draft Ordinance Overview 18.20: Definitions Many new definitions added for clarity when used in the regulations and several unnecessary.

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Presentation on theme: "Wetland Critical Areas - Draft Ordinance Overview 18.20: Definitions Many new definitions added for clarity when used in the regulations and several unnecessary."— Presentation transcript:

1 Wetland Critical Areas - Draft Ordinance Overview 18.20: Definitions Many new definitions added for clarity when used in the regulations and several unnecessary definitions removed : Establishment of Land Use Districts and Official Maps Correction to the title of soil survey New “San Juan County Possible Wetlands” map : Wetlands The proposed ordinance: Adds ‘applicability’ of regulations – within 300 feet of wetlands. Includes options for the minimum size of regulated wetlands: Option 1: various minimum sizes, based on Importance Rating Option 2: one standard minimum size

2 Wetland Critical Areas Classifies wetlands based on their type and assigns Importance Ratings: Note: the majority of wetlands in SJC are likely “Low” Importance.

3 Wetland Critical Areas Clarifies the activities allowed within wetlands and their buffers (Removes the existing list of ‘regulated’ activities). These are two long lists; please refer to the draft ordinance for this text. Removes the standard buffer width protocol and establishes a site-specific buffer procedure (see Table 3.6 and the ordinance for detailed steps): Step 1: Determine the intensity of your proposed development. Step 2: Determine if there are any wetlands within a certain distance of your development (the distance is determined by the intensity of the development). If no possible wetlands are within this area, and you are not proposing any clearing, grading, vegetation removal, drainage modification, or other development within this area, no further action is needed. Step 3: Determine the sensitivity of the wetland & identify pollutant transport risk factors. Step 4: Determine the required buffer.

4 Development IntensityPotentially Regulated Area High300 feet Medium225 feet Low80 feet Parcel Size:0-3 acres3-5 acres5-10 acres10-20 acres>20 acres Total Development Area:35%30%25%20%15% Assign a rating of LOW if implementation of the proposed development will meet all of the following: (a) The Development Area will not affect the breeding areas of animals listed by the State or Federal government as Endangered, Threatened, or Sensitive, or listed by San Juan County as a Species of Local Importance, or any plants with any of the aforementioned designations; and (b) Within the contributing area of the wetland, there are no changes in the quantity or timing of surface or groundwater flow, resulting in either more or less water directed to the wetland, due to the construction of cut-off trenches, curtain or foundation drains, ditches, berms, or ponds within the Development Parcel; and (c) Lights are directed away from wetlands and their buffers; and (d) The total Development Area comprises less than the following percentages: Staff note: The percentages shown above were derived from Semlitsch et al., Parcel Size0-3 acres3-5 acres5-10 acres10-20 acres>20 acres Total Development Area:50%45%40%35%30% Assign a rating of HIGH if implementation of the proposed development will result in any of the following: The total Development Area (including any areas where vegetation will be cleared) exceeds the following percentages: or (b) Within the contributing area of the wetland, the development action changes the quantity or timing of surface or groundwater flow, resulting in either more or less water directed to the wetland, due to construction of cut-off trenches, curtain or foundation drains, ditches, berms, ponds, etc. Assign a rating of MEDIUM if implementation of the proposed development will result in conditions that do not meet the requirements of either the High or Low ratings. Table 3.3 Development Intensity

5 Development IntensityPotentially Regulated Area High300 feet Medium225 feet Low80 feet Assign a rating of HIGH if any of the following are true: (a) A drainageway or stream connects the Development Area and a downslope wetland, and less than 300 feet separate the two; or (b) The average percent slope of land, measured from the upper edge of the Development Area to the downslope wetland, is greater than 30%; or (c) More than 10% of the land between the upper edge of the Development Area and the downslope wetland (or the downslope property line in cases where the wetland is on another parcel) meets or will meet the definition of Development Area. (For this determination, permeable pavement, permeable asphalt, and sod roofs shall not be included in the calculation of the Development Area.); or (d) The wetland is or contains a bog; or (e) During most years, the wetland has no surface water outlet flowing for more than 3 consecutive days. Temporary blockages of outflow, such as beaver dams, shall not be considered. Staff note: The numbers shown in (c), above, are derived from Booth et al., Assign a rating of MEDIUM if implementation of the proposed development will result in conditions that do not meet the requirements of either the High or Low ratings. Assign a rating of LOW if all of the following are true: (a) No drainageway or stream connects the Development Area and a downslope wetland within a distance of 300 feet; and (b) The average percent slope of land, measured from the upper edge of the Development Area and the downslope wetland, is <10%; and (c) More than 50% of the herbaceous plants and/or shrubs (i.e., woody plants with a mature height of less than 20 feet) in the wetland consist of invasive species; and (d) Less than 5% of the land between the upper edge of the Development Area and the downslope wetland (or the downslope property line in cases where the wetland is on another parcel) meets or will meet the definition of Development Area. (For this determination, permeable pavement or permeable asphalt, and sod roofs shall not be included in the calculation of the Development Area.) Staff note: The numbers shown in (d), above, are derived from Booth et al., Table 3.5 Pollutant Transport/ Wetland Sensitivity Rating

6 Development IntensityPotentially Regulated Area High300 feet Medium225 feet Low80 feet Development Intensity Pollution Transport/ Wetland Sensitivity Importance Buffer Width - Outside UGAs (ft) Buffer Width – Inside UGAs (ft) With Mitigation High 300 Medium250 Low200 Medium High250 Medium200 Low150 Low High200 Medium150 Low100 Medium High 225 Medium175 Low125 Medium High175 Medium125 Low100 Low High125 Medium100 Low7540 Low High 8040 Medium6030 Low4020 Medium High6030 Medium5025 Low2520 Low High5025 Medium5020 Low15 Table 3.6 Site-Specific Buffer Widths

7 Wetland Critical Areas Buffers can be reduced in areas where the land slopes down away from the wetland: Down to 50 feet for Medium and High Importance wetlands & 15 feet for Low Importance wetlands. The site-specific buffer procedure takes the place of the existing provisions for buffer averaging, increases, and decreases. Consolidates and revises the process, requirements, and criteria for noncompensatory enhancement projects and clarifies the contents of critical area reports. Revises the regulation of ponds in wetlands (only allowed in low importance wetlands); Repeals Appendices A (San Juan County Wetlands Rating System), B (Mitigation / Enhancement Plan Contents), and C (Bonding).

8 EXAMPLE #1: Large parcel, low intensity Check Development Intensity: 10-acre flat parcel 0.65-acre (67,015-sf) wetland 1.4-acre Development Area includes: 4,356-sf residence footprint 3,600-sf paved driveway 50,000-sf lawn 2,300 sf garden & orchard Total Development Area is less than 25% of the parcel = LOW Development Intensity Check distance to potential wetlands: 80 feet for Low Intensity Development NO FURTHER ACTION NEEDED 130 feet 660 ft. Garden & orchard Wetland 4,356-sf House footprint Lawn

9 EXAMPLE #2: Small parcel, high intensity Development Intensity: 2.5-acre flat parcel 6,500-sf wetland 1.42-acre Development Area includes: 3,300-sf residence footprint 725-sf paved driveway 56,600-sf lawn 1,200-sf garden Development Area is >50% of the parcel = HIGH Intensity Distance to potential wetlands: 300 feet Development Area extends into this area= DELINEATION REQUIRED Delineation Wet Prairie Wetland= a HIGH Importance Rating Wetland Sensitivity Rating: HIGH * 300-foot required buffer would nearly cover the parcel so development plans must be modified. Options include reducing the yard so development area is <50% (225 ft. buffer) or <35% (80 ft. buffer) or applying for a Reasonable Use Exception. 330 ft. 3,300-sf House footprint 300 ft. Lawn Garden Wetland

10 REASONABLE USE EXCEPTION FOR EXAMPLE #2: Development Intensity: 2.5-acre flat parcel 6,500-sf wetland 0.52-acre Development Area includes: 3,300-sf residence footprint 725-sf paved driveway 18,480-sf lawn 330 ft. 3,300-sf House footprint Lawn Garden Wetland


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