Raleigh -UWPOD: Urban Watershed Protection Overlay District Requirements

The Raleigh -UWPOD is designed to protect the integrity of drinking water for the City of Raleigh and surrounding communities by ensuring a supply of clean, safe water at a reasonable cost. Key regulations include a total prohibition on new landfills and strict limits on impervious surface coverage, which varies between 24% and 70% depending on the sub-area and the implementation of stormwater control measures. Every lot within the -UWPOD must also maintain an area set aside for trees equal to at least 40% of the lot area, unless specifically exempted.

General Purpose and Prohibitions

The Raleigh City Council established the Urban Watershed Protection Overlay District (-UWPOD) to apply to Class WS-IV waters. The district is divided into two distinct sub-areas: a primary water supply watershed protection area and a secondary water supply watershed protection area [Sec. 5.1.1.B.3].

Within the -UWPOD, the following uses are strictly prohibited:

New landfills; and
New sites for the land application of sludge, residuals, or petroleum-contaminated soils [Sec. 5.2.3.B].

Impervious Surface Coverage Standards

The City of Raleigh limits the amount of "built-upon area" (impervious surface) to manage runoff and protect water quality. These limits apply to all lots in existence prior to April 19, 2005, or those established outside the subdivision process after that date. No additional impervious surface may be added that exceeds the following maximum percentages:

-UWPOD Maximum Impervious Surface Coverage

Area	No Stormwater Control Measures	Retention, Detention, or Capture (First 1/2 Inch of Runoff)
Primary Water Supply Watershed Protection Areas	24% OR 2 units of single-unit living per acre OR 20,000 square foot lot	50%
Secondary Water Supply Watershed Protection Areas	24% OR 2 units of single-unit living per acre OR 20,000 square foot lot OR 3 dwellings per acre OR 36% (for projects without curb and gutter)	70%

Note: For the Secondary area, if a project is connected to both City water and sewer utilities and has a total maximum impervious surface of more than 24%, the first 1/2 inch of stormwater runoff in excess of 24% must be treated [Sec. 9.5.1.B-C].

Natural Resource Buffer Yards and Forestation

The -UWPOD mandates the protection of natural features to filter pollutants:

Buffer Yards: Natural resource buffer yards must be established along all perennial watercourses [Sec. 9.5.1.A].
Forestation Requirements: Every lot must provide and maintain an area set aside for trees equal to at least 40% of the lot area. In areas designated as "New Urban" by the Swift Creek Land Management Plan, this requirement is reduced to 25% [Sec. 9.1.9.A-C].
Tree Density: Wooded areas must consist of either active tree preservation (minimum 2 inches of tree caliper per 100 square feet) or new shade tree plantings [Sec. 9.1.9.A].

Required Stormwater Measures

When development exceeds 24% impervious surface coverage and is connected to City water and sewer, the first 1/2 inch of stormwater runoff must be managed through:

Retention for water harvesting and use on-site, infiltration, or evaporation;
Detention for at least a 12-hour period;
Capture by an approved stormwater treatment device; or
A combination of these methods [Sec. 9.5.1.C.1].

If impervious surface coverage is greater than 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].

Maintenance and Recording

When retention or detention devices serve more than one lot, the owner must record a maintenance covenant [Sec. 9.2.2.G.2]. A map must be recorded in the Wake County Registry showing the location of the device, and it must include a note stating that the facilities are required by the Raleigh City Code to be owned and maintained by a property owners' association [Sec. 9.5.1.D].

Exemptions

The -UWPOD provides specific exemptions for certain types of development:

Gravity Flow: Stormwater requirements in the secondary protection area do not apply to any lot or improvement if its runoff flows by gravity to a watercourse located outside the overlay district [Sec. 9.5.1.E.1].
Existing Single-Unit Lots: Any lot of record existing prior to October 12, 2008, containing a detached house used for single-unit living, is exempt from these area/coverage regulations, provided the lot is not contiguous to another lot owned by the same person [Sec. 9.5.1.E.2].
De Minimis Development: The impervious surface limits and capture requirements are inapplicable to any single development that disturbs less than one acre [Sec. 9.5.1.E.3].

Sections Cited

Sec. 5.1.1. District Intent Statements
Sec. 5.2.3. Urban Watershed Protection Overlay District (-UWPOD)
Sec. 9.1.9. Watershed Protection Overlay Districts
Sec. 9.2.2. Active Stormwater Control Measures
Sec. 9.5.1. Urban Watershed Protection Overlay District (-UWPOD)