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Appendix A:

Fixed Method 

Summit County Model 

Calculated Method

Setback Models

 

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Considerations For Developing Riparian Setbacks

Appendix A

 

 

 

REASONS to Establish  Riparian SETBACKS:

 

1. Flooding is a significant threat to public health and safety as well as to property. Riparian areas lessen flood damage by holding runoff and releasing  it slowly over time.

 

2. Streambank erosion is a significant threat to public health and safety as well as to property. Riparian areas control runoff, reduce its erosive force, and  keep structures out of harm’s way.

 

3. Misuse of riparian areas can result in significant damage to receiving water resources, reducing the quality of the aquatic habitat.

 

4. The Community has an obligation as a part of a watershed to reduce flooding and erosion and to protect water quality by controlling runoff within its borders.

 

5. Setbacks provide homebuilders, developers, and landowners with standards for storm water management.

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PURPOSE OF Riparian Setbacks:

 

1. Protect the receiving stream's physical, chemical, and biological characteristics and to maintain stream functions.

 

2. Establish standards to achieve a level of storm water quantity and quality control that will minimize damage to property and degradation of water resources, and will promote and maintain the health, safety, and welfare of the residents of the Community.

 

3. Preserve to natural drainage characteristics and minimize the need to construct, repair, and replace enclosed storm drain systems.

 

4. Preserve natural infiltration and ground water recharge, and maintain subsurface flow that replenishes water resources, wetlands, and wells.

 

5. Prevent unnecessary stripping of vegetation and loss of soil, especially adjacent to water resources and wetlands.

 

6. Reduce the need for costly maintenance and repairs to infrastructure that result from inadequate storm water control due to the loss of riparian areas and wetlands.

 

7. Reduce the long term expense of remedial projects needed to address problems caused by inadequate storm water control.

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BENEFITS PROVIDED BY RIPARIAN AREAS:

 

1. Reduce flood impacts by absorbing peak flows, slowing the velocity of floodwaters, and regulating base flow.

 

2. Assist in stabilizing the banks of watercourses to reduce bank erosion and the downstream transport of sediments eroded from watercourse banks.

 

3. Reduce pollutants in watercourses during periods of high flows by filtering, settling, and transforming pollutants already present in watercourses.

 

4. Reduce pollutants in watercourses by filtering, settling, transforming and absorbing pollutants in runoff before they enter watercourses.

 

5. Provide watercourse habitats with shade and food.

 

6. Provide habitat to a wide array of aquatic organisms, wildlife, many of which are on Ohio's Endangered and/or Threatened Species listings, by maintaining diverse and connected riparian and wetland vegetation.

 

7. Benefit the Community economically by minimizing the need for costly engineering solutions to protect structures and reduce property damage and threats to the safety of residents; and by contributing to the scenic beauty and environment of the Community, and thereby preserving the character of the Community, the quality of life of the residents of the Community, and corresponding property values.

 

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USES THAT MAY BE ALLOWED IN RIPARIAN SETBACKS:

 

1.   Without A Permit:

1. Passive recreational uses such as hiking, fishing, hunting, picnicking, and similar uses.

 

2. Removal of damaged or diseased trees.

 

3. Revegetation and/or reforestation with non-invasive plant species.

 

4. Lawns, gardens and landscaping, that existed at the time the ordinance is passed, may be maintained as long as they are not increased in size.

 

2.      With A Permit:

1. Selective harvesting of timber.

 

2. Streambank stabilization and erosion control measures may be allowed provided that such measures are ecologically compatible and substantially utilize natural materials and native plant species where practical.

 

3. Crossing sewer and/or water lines, public and private utility transmission lines, and easements to access areas outside of the setback.

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USES THAT MAY BE PROHIBITED IN RIPARIAN SETBACKS:

 

1. Construction.

 

2. Dredging or Dumping.

 

3. Roads or Driveways.

 

4. Motorized Vehicles.

 

5. Disturbance of Natural Vegetation (such as mowing).

 

6. Parking Lots (or other human-made impervious cover).

 

7. Sewage Disposal or Treatment Areas.

 

 

ESTABLISHMENT OF DESIGNATED WATERCOURSES AND RIPARIAN SETBACKS:

 

Stream setback widths are based on stream processes that cause streams to adjust to their meander pattern and maintain dynamic stability (erosion = deposition). It best estimates the corridor in which stream meander migration is likely to occur over time and it provides a minimum level of protection for each streambank.

 

There are two methods for establishing setback widths. Both methods use the size of a stream’s drainage area to establish the dimensions of the setback. In the first method, fixed widths are assigned based on a drainage area range, while in the second method; an empirically derived equation is employed to calculate the setback area.

 

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FIXED METHOD

 

Two ordinances employing the fixed width method have been developed in Northeast Ohio, one by the Chagrin River Watershed Partners, Inc. and the other by Summit County. Either would be an excellent model to consider.

 

 

 

The Chagrin River Watershed Partners, Inc. Model:

 

 

1.      Designated watercourses shall include those watercourses meeting any one of the following criteria:

 

1. All watercourses draining an area greater than ½ square mile, or

 

2. All watercourses draining an area less than ½ square mile and having a defined bed and bank.

 

2.      Riparian setbacks on designated watercourses are established as follows:

 

1. A minimum of 300 feet on both sides of all watercourses draining an area greater than 300 square miles.

 

2. A minimum of 120 feet on both sides of all watercourses draining an area greater than 20 square miles and up to and including 300 square miles.

 

3. A minimum of 75 feet on both sides of all watercourses draining an area greater than one half square mile and up to and including 20 square miles.

 

4. A minimum of 25 feet on both sides of all watercourses draining an area less than one half square mile and having a defined bed and bank as determined above.

 

 

3.      The following conditions should apply in riparian setbacks:

 

1. Riparian setbacks should be preserved in their natural state and should be established and marked in the field prior to any soil disturbing or land clearing activities.

 

2. Where the 100-year floodplain is wider than a riparian setback, the riparian setback should be extended to the outer edge of the 100-year floodplain.

 

3. Where wetlands are identified within a riparian setback, the minimum riparian setback width should be extended to the outer boundary of the wetland.

 

4. Wetlands should be delineated by a site survey using delineation protocols accepted by the U.S. Army Corps of Engineers and the Ohio EPA.

 

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Summit County Model

 

1.      An affected stream is defined as a surface watercourse with a well-defined bed and bank, either natural or artificial, which confines and conducts continuous or periodical flowing water in such a way that terrestrial vegetation cannot establish roots within the channel.

 

2.      Widths of setbacks are measured as horizontal map distance outward from the ordinary high water mark on each side of a stream and are established as follows:

 

1. A minimum of 300 feet on each side of all streams draining an area greater than 300 square miles.

 

2. A minimum of 100 feet on each side of all streams draining an area greater than 20 square miles and up to 300 square miles.

 

3. A minimum of 75 feet on each side of all streams draining an area greater than 0.5 square mile (320 acres) and up to 20 square miles.

 

4. A minimum of 50 feet on each side of all streams draining an area greater than 0.05 square mile (32 acres) and up to 0.5 square mile (320 acres).

 

5. A minimum of 30 feet on each side of all streams draining an area less than 0.05 square mile (32 acres).

 

 

 

3.      Where the 100-year floodplain is wider than the Riparian Setback on either or both sides of the stream, the Riparian Setback should be extended to the outer edge of the 100-year floodplain.

 

4.      Because the gradient of the riparian corridor significantly influences impacts on the stream, the following adjustment for steep slopes will be integrated into the Riparian Setback formulae for width determination:

 

 

 

 

 

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CALCULATED METHOD

 

The setback area width is a total width, which crosses the channel and is calculated according to the drainage area (miles²) of the stream using the following equation:

 

Setback Area Width = 129 Drainage Area^0.43

 

1.      When calculating the setback width:

 

1. A minimum total width of 50 feet should be applied to all streams with a defined bed and bank in which flow occurs.

 

2. As tributaries enter a stream, the additional drainage areas will need to be added to calculate the setback area width at those locations. This method will produce a setback area that gets appropriately larger as you proceed downstream.

 

2.      If there are wetlands or floodplains on the site, the setback area should ideally be expanded from the minimum width calculated to include these and associated buffer areas, since they provide hydrologic and other benefits.

 

3.      Locate the setback area by placing the centerline of the area over the centerline of the watercourse. Move the area based on the site topography and changes in stream and valley direction.

 

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APPLYING THE SETBACK MODELS

 

The map on the following page shows the main streams running through Seville:

 

Chippewa Creek (Ch), Hubbard Creek (Hb), and 4 unnamed streams that will be referred to as streams A, B, C and D.

 

The drainage areas of these streams have been calculated up to each of the labeled dots. Table “1” compares of  the setback widths determined by each of the 3 models.