Falls Watershed Protection Overlay District (-FWPOD) Standards in Raleigh
The -FWPOD: Falls Watershed Protection Overlay District is a specialized regulation in the City of Raleigh designed to protect the integrity of drinking water by imposing strict limits on land development. This overlay district modifies base zoning by prohibiting high-impact uses like landfills, capping impervious surface coverage between 6% and 70% depending on location and utility connectivity, and requiring mandatory tree conservation areas equal to 40% of a lot's area.
Purpose and General Applicability
The City of Raleigh established the -FWPOD to safeguard drinking water for the municipality and surrounding communities. It ensures clean and safe water for residents, businesses, and ecosystems at a reasonable cost. The district applies to Class WS-IV waters and is divided into two primary zones: the primary reservoir watershed protection area and the secondary reservoir watershed protection area [Sec. 5.1.1.B.4].
In the event of a conflict between the standards of the -FWPOD and the underlying base zoning district, the more restrictive overlay standards shall control [Sec. 5.1.1.A.3].
Prohibited Uses
The -FWPOD places an absolute prohibition on certain high-impact activities that could jeopardize water quality. Within the boundaries of the City of Raleigh -FWPOD, new landfills are strictly prohibited [Sec. 5.2.4.B.1].
Impervious Surface Coverage Limits
The -FWPOD significantly modifies the allowed "built-upon area" (impervious surface) compared to standard districts. These limits are determined by the specific sub-area of the watershed and whether the development is connected to City of Raleigh water and sewer utilities.
-FWPOD Maximum Impervious Surface Coverage
| Area Description | No Stormwater Control Measures | With Retention, Detention, or Capture (First 1/2" of Runoff) | Management of First Inch of Rainfall |
|---|---|---|---|
| Primary water supply watershed protection areas | 6% or 3,500 sq. ft. (if not more than 12%) | N/A | N/A |
| Secondary area (Not connected to City water/sewer) | 12% or 3,500 sq. ft. (if not more than 24%) | N/A | N/A |
| Secondary area (Connected to City water/sewer) | 12% or 3,500 sq. ft. (if not more than 24%) | 24% | 30% built area; or 3,500 sq. ft. (if not more than 50%); or 70% in designated high-density areas |
[Sec. 9.5.2.B.1]
For lots connected to both City water and sewer in secondary areas, if the impervious surface exceeds 12%, the first 1/2 inch of stormwater runoff must be managed through harvesting, infiltration, or approved treatment devices [Sec. 9.5.2.C.1]. If built area exceeds 24%, the first inch of rainfall must be captured and managed [Sec. 9.5.2.C.1.b].
Nutrient Loading Requirements
The City of Raleigh requires that new development and expansions within the -FWPOD do not exceed specific unit-area mass loading rates for nitrogen and phosphorus. These standards are supplemental to state or federal riparian buffer requirements [Sec. 9.5.2.D.1.b].
-FWPOD Nutrient Export Limits
| Nutrient Type | Unit-Area Mass Loading Rate (Max) |
|---|---|
| Nitrogen | 2.2 pounds per acre per year |
| Phosphorus | 0.33 pounds per acre per year |
[Sec. 9.5.2.D.1.b]
Developers may use off-site management measures or purchase nutrient offset credits to meet these targets, provided they first implement on-site structural controls that achieve a minimum 60% reduction in the increased loading rate [Sec. 9.5.2.D.1.c].
Mandatory Forestation and Tree Conservation
The -FWPOD imposes a higher threshold for tree preservation than standard City of Raleigh districts. Every lot within the overlay must provide and maintain an area set aside for trees equal to at least 40% of the total lot area [Sec. 9.5.2.G].
Within this 40% area:
- Tree areas may be contiguous or scattered, but no single area may be less than 1/5 of the total required land area for trees [Sec. 9.1.9.A.1].
- Wooded areas must be maintained as such, utilizing either active tree preservation or new tree planting [Sec. 9.1.9.A.2].
- Active preservation areas must contain at least 2 inches of tree caliper per 100 square feet [Sec. 9.1.9.A.4].
- New tree plantings must follow specific rates: either 1 bare-root seedling (at least 14 inches tall) per 100 square feet or one 2-inch caliper shade tree per 200 square feet [Sec. 9.1.9.A.6].
Stormwater Control and Maintenance
All stormwater control measures (SCMs) required in the -FWPOD must be recorded via a maintenance covenant. This covenant ensures that the City of Raleigh has a permanent non-exclusive easement for inspections and repairs if the owner fails to maintain the facility [Sec. 9.5.2.E]. Additionally, the developer must pay a "stormwater facility replacement fund" fee equal to 24% of the estimated construction cost of the SCMs [Sec. 9.2.2.G.3].
Sections Cited
- Section 5.1.1. District Intent Statements
- Section 5.2.4. Falls Watershed Protection Overlay District (-FWPOD)
- Section 9.1.9. Watershed Protection Overlay Districts
- Section 9.2.2. Active Stormwater Control Measures
- Section 9.5.2. Falls Watershed Protection Overlay District (-FWPOD)