Regulations of the -UWPOD: Urban Watershed Protection Overlay District
The Urban Watershed Protection Overlay District (-UWPOD) in the City of Raleigh modifies base standards by prohibiting high-impact uses like landfills, requiring a 40% tree conservation area on most lots, and strictly limiting impervious surface coverage. The City of Raleigh mandates that developments within this district maintain natural resource buffers of up to 100 feet along perennial watercourses and implement specific stormwater control measures once imperviousness exceeds 24%.
Intent and Applicability
The City of Raleigh established the -UWPOD to protect the integrity of drinking water for the community. The district ensures clean and safe water for residents, businesses, and animal life by imposing additional standards on land within Class WS-IV waters [Sec. 5.1.1.3]. These regulations are divided into primary and secondary water supply watershed protection areas. In any instance where the standards of the -UWPOD conflict with the underlying general use district, the more restrictive overlay standards shall apply [Sec. 5.1.1.3].
Prohibited Uses
The -UWPOD prohibits certain uses that are otherwise allowed in base zoning districts. Within the City of Raleigh, the following uses are strictly prohibited in this overlay:
- New landfills; and
- New sites for the land application of sludge, residuals, or petroleum-contaminated soils [Sec. 5.2.3.B].
Impervious Surface Coverage Limits
The City of Raleigh limits the amount of "built-upon area" (impervious surface) permitted on a lot within the -UWPOD. These limits vary depending on whether the property is in a primary or secondary area and if the developer utilizes active stormwater control measures [Sec. 9.5.1.B].
| Area | No Stormwater Control Measures | With Retention, Detention, or Capture (First 1/2" of Runoff) |
|---|---|---|
| Primary Water Supply Watershed Protection Areas | 24% or 2 units of single-unit living per acre (or 20,000 SF lot) | 50% |
| Secondary Water Supply Watershed Protection Areas | 24% or 2 units of single-unit living per acre (or 20,000 SF lot) OR 3 dwellings per acre OR 36% for projects without curb/gutter | 70% |
Natural Resource Buffer Yards
The City of Raleigh requires the establishment of natural resource buffers along all perennial watercourses in the -UWPOD. These buffers provide a filtered area where stormwater can flow in a diffuse manner [Sec. 9.2.3.A.1].
| Condition | Minimum Buffer Width |
|---|---|
| All perennial waters (identified on USGS 1:24,000 maps) | 30 feet |
| New development exceeding 2 units/acre or 20,000 SF lot | 100 feet |
| New development exceeding 24% lot coverage (all other types) | 100 feet |
Note: These buffers do not apply to new detached houses on a nonconforming lot of record or activities disturbing less than one acre [Sec. 9.2.3.A.4.c].
Tree Conservation and Forestation
Every lot located within a City of Raleigh -UWPOD must provide and maintain an area set aside for trees equal to at least 40% of the total lot area [Sec. 9.1.9.A].
- Contiguity: Required tree areas can be one contiguous block or scattered, provided no single area is less than 1/5 of the total required land area.
- Standards: These areas must be maintained as wooded areas, consisting of either active tree preservation (requiring a minimum of 2 inches of tree caliper per 100 square feet) or new shade tree plantings [Sec. 9.1.9.A].
- Exception: This requirement does not apply to lots in areas where the City of Raleigh Comprehensive Plan allows for impervious surfaces in excess of 30%, or to lots used for governmental water/wastewater treatment [Sec. 9.1.9.E-F].
Stormwater Control Requirements
In the City of Raleigh, any lot in the -UWPOD primary or secondary areas that is connected to City water and sewer and exceeds 24% impervious surface must implement active stormwater measures [Sec. 9.5.1.C]. The first 1/2 inch of stormwater runoff in excess of 24% must be:
- Retained for water harvesting and onsite use;
- Infiltrated into the soil;
- Evaporated into the air;
- Detained for at least a 12-hour period; or
- Captured by an approved stormwater treatment device [Sec. 9.5.1.C.1].
If the impervious surface exceeds 24%, the first inch of stormwater running off any street must also be contained within the development using the methods listed above [Sec. 9.5.1.C.2].
Sections Cited
- Section 5.1.1. District Intent Statements
- Section 5.2.3. Urban Watershed Protection Overlay District (-UWPOD)
- Section 9.1.9. Watershed Protection Overlay Districts
- Section 9.2.3. Watercourse Buffers
- Section 9.5.1. Urban Watershed Protection Overlay District (-UWPOD)