Water Quality Buffers
New development and significant redevelopment sites are required to preserve water quality buffers along Metro’s community waters. Buffers shall be clearly marked on site development plans, Grading Permit applications, and/or concept plans. Community waters include the following:
- Intermittent and perennial streams (and their source springs)
- Lakes and ponds with hydrologic connectivity (stream leading into/out of the pond or obvious spring input)
- Wetlands that have been identified by the U.S. Army Corps of Engineers, TDEC, or MWS staff.
Intermittent streams are natural or man-made watercourses (streams), which may cease to flow for sustained periods during a normal rainfall year (typically during the later summer through fall months). Perennial streams generally flow year-round, however they too may also run dry during years of extreme drought.
To determine if a conveyance is a community water and requires a buffer, a developer must assess all streams identified on Metro’s GIS stream layer and conveyances draining > 40 acres. Both NPDES and TDEC will perform a hydrologic determination free of charge. A developer may also use qualified staff and the TDEC/MWS Hydrologic Determination Policy to make a determination on the water feature. Please note, some community waters are not shown on either the GIS stream layer or drain an area greater than 40 acres. These community waters still require a buffer and should be identified when the property is surveyed.
The following buffer widths and zones shall be applied to community waters. Zone 1 is a “no disturb zone”, where the vegetation cannot be cut, removed, or replanted unless a buffer restoration plan has been approved by MWS. Zone 2 can consist of managed vegetation such as turf grass; however, no structures or impervious surfaces shall be placed in Zone 2.
Streams
- Streams draining < 100 acres: 30’ from top of bank; Zone 1=30’
- Streams draining ≥ 100 acres, but < 1 square mile: 50’ from top of bank; Zone 1=30’ and Zone 2=20’
- FEMA studied streams or streams with a drainage area ≥ 1 square mile: 75’ from the floodway, Zone 1=floodway + 50’ and Zone 2=25’
Ponds
Ponds with hydrologic connectivity: 25’ from normal water pool, Zone 1 = 10’ and Zone 2 = 15’
Wetlands
25’ from the wetland delineation line, Zone 1=25’
Buffers shall be preserved both during development and perpetually after development.
- During development, Zone 1 of all buffers shall be clearly marked and protected from construction activities. Zone 2 may be disturbed and revegetated.
- Water quality buffers shall be placed in open space easements recorded with the deed for the property.
- Prior to the release of the stormwater system bond, water quality buffer limits shall be clearly marked with permanent signs placed every 100 feet along the outside edge of Zone 1 (the edge furthest from the stream). See below for additional information.
- Projects that disturb buffers for enhancement or restoration shall be allowed with prior approval from MWS.
Buffer Signs
Buffer signs may be purchased from Jarvis Signs (615-865-6062). If you would like to use another vendor, please use the specs provided below and contact MWS for the artwork.
Description:
- 12" X 18" white 0.063 aluminum
- black and kelley green copy
- single sided
- sign to be mounted to post at top and bottom with stainless steel hardware
Post Description:
- 6' galvanized U-channel or 4" x 4" pressure treated lumber post
- 2' below grade
- 4' above grade
For more information on Water Quality Buffers, please see Section 6.9 of the SWMM. For information on Floodplain protection, please see Section 5.4.