WSMU_MILL_WSWP Ordinance_20230712

§ 154.048 WATER SUPPLY WATERSHED PROTECTION OVERLAY DISTRICT.
(A) Purpose. The purpose of the Water Supply Watershed Protection Overlay District (the
"Watershed Protection District") is to define the Water Supply Watershed Protection Areas within the
Town of Mills River and regulate the use of land, average lot size and development density and
intensity in order to maintain a high quality of surface water and limit the impact from existing or
potential sources of contamination in the Public Water Supply Watershed as designated by the N.C.
Environmental Management Commission.
(B) Establishment of areas. Water Supply Watershed Protection Areas ("Watershed Protection
Areas") shall be defined and established on the map entitled, "Watershed Protection Map of the Town
of Mills River, North Carolina" (the "Watershed Map"). The Watershed Map and all explanatory matter
contained thereon accompanies and is hereby adopted as part of the Mills River Town Code. For
purposes of this section, areas of the town may be divided into the following areas as depicted on the
Watershed Map and amendments thereto:
WS-I
WS-II-CA (Critical Area)
WS-II-BW (Balance of Watershed)
WS-III-CA (Critical Area)
WS-III-BW (Balance of Watershed)
WS-IV-CA (Critical Area)
WS-IV-PA (Protected Area)
(C) Application of regulations. No structure or land shall hereafter be used and no development
shall take place in the Watershed Protection District except in conformity with this section for the
Watershed Protection Area in which it is located. The following exceptions shall be made in the
application of the Watershed Protection District regulations.
(1) Expansions to structures classified as existing development must meet the requirements of
this section. However, the built-upon area of the existing development is not required to be included in
density calculations.
(2) It is not intended that these regulations interfere with any easement, covenants or other
agreements between parties. However, if the provisions of these regulations impose greater
restrictions or higher standards for the use of a building or land, then the provisions of these
regulations shall control.
(3) If a nonconforming lot of record is not contiguous to any other lot owned by the same party,
then that lot of record shall not be subject to the development restrictions of this section if it is
developed for single-family residential purposes.
(4) Any lot or parcel created as part of a family subdivision after the effective date of this section
shall be exempt from this section if it is developed for 1 single-family detached residence. Any lot or
parcel created as part of any other type of subdivision that is exempt from the Subdivision Ordinance
shall be subject to the requirements of this section.
(5) Any lot created for a cemetery plot shall be exempt from this section.
(D) Watershed Protection Areas requirements.
(1) WS-I Watershed Protection Areas. The intent is to provide maximum protection for water
supplies within natural and undeveloped watersheds in public ownership by allowing only low intensity

uses. No residential or non-residential uses are allowed except those listed below. Impacts from non-
point source pollution shall be minimized.
(a) Allowed uses.
1. Agriculture subject to the provisions of the Food Security Act of 1985 and the Food,
Agriculture, Conservation and Trade Act of 1990 and all rules and regulations of the Soil and Water
Conservation Commission.
2. Silviculture, subject to the provisions of the Forest Practices Guidelines Related to Water
Quality (15 NCAC 11.6101-.0209).
3. Water withdrawal, treatment and distribution facilities.
4. Restricted road access.
5. Power transmission lines.
(b) Density and built-upon area limits do not apply.
(2) WS-ll Watershed Protection Areas - Critical Area (WS-II-CA). In order to maintain a
predominately undeveloped land use intensity pattern, single-family residential uses shall be allowed
at a maximum of 1 dwelling unit per 80,000 square foot lot. All other residential and non-residential
development shall be allowed at a maximum 6% built-upon area. New residuals application sites and
landfills are specifically prohibited.
(a) Allowed uses.
1. Agriculture subject to the provisions of the Food Security Act of 1985 and the Food,
Agriculture , Conservation and Trade Act of 1990 and the rules and regulations of the Soil and Water
Conservation Commission.
2. Silviculture, subject to the provisions of the Forest Practices Guidelines Related to Water
Quality (15 NCAC 11.6101-.0209).
3. Residential development .
4. Non-residential development , excluding landfills and sites for land application of residuals
or petroleum contaminated soils.
(b) Density and built-upon limits.
1. No single-family residential lot shall be less than 80,000 square feet excluding roadway
right-of-way, except within an approved cluster development .
2. All other residential and non-residential development shall not exceed 6% built-upon area
on a project by project basis. For the purpose of calculating built-upon area, total project area shall
include total acreage in the tract on which the project is to be developed.
(3) WS-Il Watershed Areas - Balance of Watershed (WS-II-BW). In order to maintain
predominantly undeveloped land use intensity, single family residential uses shall be allowed at a
maximum of 1 dwelling unit per 40,000 square foot lot. All other residential and non-residential
development shall be allowed a maximum of 12% built-upon area. Non-discharging landfills and
residuals application sites are allowed.
(a) Allowed uses.
1. Agriculture , subject to the provisions of the Food Security Act of 1985 and the Food,
Agricultural, Conservation and Trade Act of 1990.

2. Silviculture, subject to the provisions of the Forest Practices Guidelines Related to Water
Quality (15 NCAC 11.0101-.0209).
3. Residential development .
4. Non-residential development excluding discharging landfills .
(b) Density and built-upon limits.
1. No single-family residential lot shall be less than 40,000 square feet excluding roadway
right-of-way, except within an approved cluster development .
2. All other residential and non-residential development shall not exceed 12% built-upon area
on a project by project basis. For the purpose calculating built-upon area, total project area shall
include total acreage in the tract on which the project is to be developed.
(4) WS-lIl Watershed Areas - Critical Area (WS-III-CA). In order to maintain low to moderate land
use intensity, single family residential uses are allowed at a maximum of 1 dwelling unit per 40,000
square foot lot. All other residential and non-residential development shall be allowed to at a
maximum of 12% built-upon area. New residuals application sites and landfills s are specifically
prohibited.
(a) Allowed uses.
1. Agriculture , subject to the provisions of the Food Security Act of 1985 and the Food,
Agriculture , Conservation and Trade Act of 1990 and the rules and regulations of the Soil and Water
Conservation Commission.
2. Silviculture, subject to the provisions of the Forest Practices Guidelines Related to Water
Quality (15 NCAC 11.0101-.0209).
3. Residential.
4. Non-residential development , excluding landfills and sites for land application of residuals
or petroleum contaminated soils.
(b) Density and built-upon limits.
1. No single family residential lot shall be less than 40,000 square feet excluding roadway
right-of-way, except within an approved cluster development .
2. All other residential and non-residential development shall not exceed 12% built-upon area
on a project by project basis. For the purpose of calculating built-upon area, the total project area shall
include total acreage in the tract on which the project is to be developed.
(5) WS-III Watershed Areas - Balance of Watershed (WS-Ill-BW). In order to maintain a low to
moderate land use intensity, single-family detached uses shall develop at a maximum of 1 dwelling
unit per 20,000 square foot lot. All other residential and non-residential development shall be allowed
at a maximum of 24% built-upon area. Non-discharging landfills and residuals application sites are
allowed.
(a) Allowed uses.
1. Agriculture , subject to the provisions of the Food Security Act of 1985 and the Food,
Agricultural, Conservation and Trade Act of 1990.
2. Silviculture, subject to the provisions of the Forest Practices Guidelines Related to Water
Quality (15 NCAC 11.0101-.0209).
3. Residential development .

4. Non-residential development excluding discharging landfills .
(b) Density and built-upon limits.
1. No single-family residential lot shall be less than 20,000 square feet excluding roadway
right-of-way, except within an approved cluster development .
2. All other residential and non-residential development shall not exceed 24% built-upon area
on a project by project basis. For the purpose of calculating built-upon area, total project area shall
include total acreage in the tract on which the project is to be developed.
(6) WS-IV Watershed Areas - Critical Area (WS-IV-CA). Only new development activities that
require an erosion/sedimentation control plan under state law or approved local program are required
to meet the provisions of this section when located in a WS-IV watershed. In order to address a
moderate to high land use intensity pattern, single-family residential uses are allowed at a maximum
of 1 dwelling unit per 20,000 square foot lot. All other residential and non-residential development
shall be allowed at a maximum of 24% built-upon area. New residuals application sites and landfills
are specifically prohibited.
(a) Allowed uses.
1. Agriculture subject to the provisions of the Food Security Act of 1985 and the Food,
Agriculture , Conservation and Trade Act of 1990 and the rules and regulations of the Soil and Water
Conservation Commission.
2. Silviculture, subject to the provisions of the Forest Practices Guidelines Related to Water
Quality (15 NCAC 11.0101-.0209).
3. Residential.
4. Non-residential development , excluding landfills and sites for land application of residuals
or petroleum contaminated soils.
(b) Density and built-upon limits.
1. No single-family residential lot shall be less than 20,000 square feet excluding roadway
right-of-way, except within an approved cluster development .
2. All other residential and non-residential development shall not exceed 24% built-upon area
on a project by project basis. For the purpose of calculating the built-upon area, total project area shall
include total acreage in the tract on which the project is to be developed.
(7) WS-IV Watershed Areas - Protected Area (WS-IV-PA). Only new development activities that
require an erosion/sedimentation control plan under state law or approved local government program
are required to meet the provisions of this section when located in a WS-IV watershed. In order to
accommodate moderate to high land use intensity, single-family residential uses shall develop at a
maximum of 1 dwelling unit per 20,000 square foot lot. All other residential and non-residential
development shall be allowed at a maximum of 24% built-upon area. A maximum of 3 dwelling units
per acre (3 du/ac) or 36% built-upon area is allowed for projects without a curb and gutter street
system.
(a) Uses allowed.
1. Agriculture , subject to the provisions of the Food Security Act of 1985 and the Food,
Agricultural, Conservation and Trade Act of 1990.
2. Silviculture, subject to the provisions of the Forest Practices Guidelines Related to Water
Quality (15 NCAC 11.0101-.0209).
3. Residential development .

4. Non-residential development .
(b) Density and built-upon limits.
1. No single-family residential lot shall be less than 20,000 square feet excluding roadway
right-of-way, except within an approved cluster development .
2. All other residential and non-residential development shall not exceed 24% built-upon area
on a project by project basis. For residential projects without a curb and gutter street system and with
natural drainage and filtering design elements, development shall not exceed 36% built-upon area on
a project by project basis. For the purpose of calculating built-upon area, total project area shall
include acreage in the tract on which the project is to be developed.
(E) The Watershed Administrator may approve high density development proposals consistent
with the following standards. High density development shall meet the requirements of the Mills River
Town Code.
(1) WS-lI Watershed Areas - Critical Area (WS-II-CA). Where new development exceeds either 1
dwelling unit per 2 acres or 6% built-upon area, engineered stormwater controls shall be used to
control runoff from the first inch of rainfall and development shall not exceed 24% built-upon area.
(2) WS-II Watershed Areas - Balance of Watershed (WS-II-BW). Where new development
exceeds either 1 dwelling unit per acre or 12% built-upon area, engineered stormwater controls shall
be used to control runoff from the first inch of rainfall and development shall not exceed 30% built-
upon area.
(3) WS-IIl Watershed Areas - Critical Area (WS-III-CA). Where new development exceeds either
1 dwelling unit per acre or 12% built-upon area, engineered stormwater controls shall be used to
control runoff from the first inch of rainfall and development shall not exceed 30% built-upon area.
(4) WS-lll Watershed Areas - Balance of Watershed (WS-Ill-BW). Where new development
exceeds either 2 dwelling units per acre or 24% built-upon area, engineered stormwater controls shall
be used to control runoff from the first inch of rainfall and development shall not exceed 50% built-
upon area.
(5) WS-IV Watershed Areas - Critical Area (WS-IV-CA). Where new development exceeds either
2 dwelling units per acre or 24% built-upon area, engineered stormwater controls shall be used to
control runoff from the first inch of rainfall and development shall not exceed 50% built-upon area.
(6) WS-IV Watershed Areas - Protected Area (WS-IV-PA). Where new development requires a
sedimentation/erosion control plan and exceeds either 2 dwelling units per acre or 24% built-upon
area or 3 dwelling units per area or 36% built-upon area for projects without curb and gutter street
systems, engineered stormwater controls shall be used to control runoff from the first inch of rainfall
and development shall not exceed 70% built-upon area.
(F) Mixed-use development . In cases where both residential and non-residential uses are
proposed for 1 lot in single ownership, such mixed-use developments may be permitted without
further subdivision of the lot. However, each use must adhere to its respective density /built-upon area
requirements. For purposes of this section, home occupations shall, be considered as residential
uses.
(G) Existing development. Existing development as defined in this chapter, may be continued and
maintained subject to the provisions provided herein. Expansions to structures classified as existing
development must meet the requirements of this section. However, the built-upon area of the existing
development is not required to be included in the built-upon area calculations.
(1) Uses of land. This category consists of uses existing as of the effective date of this section
where such use of the land is not permitted to be established hereafter in the watershed area in which

it is located. Such uses may be continued except as follows:
(a) When such use of land has been changed to an allowed use, it shall not thereafter revert to
any prohibited use.
(b) Such use of land shall be changed only to an allowed use.
(c) When such use ceases for a period of at least 1 year, it shall not be reestablished.
(2) Reconstruction of buildings or built-upon areas. Any existing building or built-upon area not in
conformance with the requirements of this section that has been damaged or removed may be
repaired and/or reconstructed, except that there are no restrictions on single family residential
development, provided:
(a) Repair or reconstruction is initiated within 12 months and completed within 2 years of such
damage.
(b) The total amount of space devoted to built-upon area may not be increased unless
stormwater control measures that equal or exceed the previous development are provided.
(3) Existing vacant lots . Existing vacant lots are lots for which plats or deeds have been recorded
as of May 23, 1994 in the office of the Register of Deeds of Henderson County. An existing lot may be
used for any of the uses allowed in the Watershed Protection Area in which it is located provided that
where the lot size is less than the minimum specified in this section, the project requires the issuance
of a permit or permits as required by the Mills River Town Code.
(H) Buffer requirements. All uses within Watershed Protection Areas shall be required to maintain a
minimum 30 foot vegetated buffer from perennial stream banks; provided, however, that where
development is approved as a high-density development , the setback from perennial streams shall
be 100 feet. Perennial streams shall be identified as indicated on the most recent version of the USGS
1:24,000 (7.5 minute) scale topographic maps or as determined by local government studies. Where
USGS topographical maps do not distinguish between perennial and intermittent streams, an on-site
stream determination may be performed by an individual qualified to perform such stream
determinations. Water-dependent structures and public projects, such as road crossings and
greenways, may be allowed where no practical alternative exists. The activities shall minimize built-
upon surface area and maximize the use of stormwater best management practices.
(I) Cluster development. Cluster development is allowed in designated Watershed Protection Areas
in accordance with § 154.080 of this chapter, and under the following conditions.
(1) Minimum lot sizes are not applicable to single family cluster development projects; however,
the total number of lots shall not exceed the number of lots allowed for single family detached
developments in § 303. Density or built-upon area for the project shall not exceed that allowed for the
critical area, balance of watershed or protected area, whichever applies.
(2) All built-upon area shall be designed and located to minimize stormwater runoff impact to the
receiving waters and minimize concentrated stormwater flow, maximize the use of sheet flow through
vegetated areas, and maximize the flow length through vegetated areas.
(3) Areas of concentrated density development shall be located in upland area and away, to the
maximum extent practicable, from surface waters and drainageways.
(4) The remainder of the tract shall remain in a vegetated or natural state. The title to the open
space area shall be conveyed to an incorporated homeowners association for management; to a local
government for preservation as a park or open space; or to a conservation organization for
preservation in a permanent easement. Where a property association is not incorporated, a
maintenance agreement shall be filed with the property deeds.

(5) Cluster developments that meet the applicable low density requirements shall transport
stormwater runoff by vegetated conveyances to the maximum extent practicable.
(J) Density averaging. An applicant may average development density on up to 2 noncontiguous
properties for purposes of achieving compliance with the water supply watershed development
standards if all of the following circumstances exist:
(1) The properties are within the same water supply watershed. If 1 of the properties is located in
the critical area of the watershed, the critical area property shall not be developed beyond the
applicable density requirements for its classification.
(2) Overall project density meets applicable density or stormwater control requirements under
15A NCAC 2B.0200.
(3) Vegetated setbacks on both properties meet the minimum statewide water supply watershed
protection requirements.
(4) Built-upon areas are designed and located to minimize stormwater runoff impact to the
receiving waters, minimize concentrated stormwater flow, maximize the use of sheet flow through
vegetated areas, and maximize the flow length through vegetated areas.
(5) Areas of concentrated density development are located in upland areas and, to the maximum
extent practicable, away from surface waters and drainageways.
(6) The property or portions of the properties that are not being developed will remain in a
vegetated or natural state and will be managed by a homeowners' association as common area,
conveyed to a local government as a park or greenway, or placed under a permanent conservation or
farmland preservation easement unless it can be demonstrated that the local government can ensure
long-term compliance through deed restrictions and an electronic permitting mechanism. A metes and
bounds description of the areas to remain vegetated and limits on use shall be recorded on the
subdivision plat, in homeowners' covenants, and on individual deed and shall be irrevocable.
(7) Development permitted under density averaging and meeting applicable low density
requirements shall transport stormwater runoff by vegetated conveyances to the maximum extent
practicable.
(8) A special use permit or other such permit or certificate shall be obtained from the local
Watershed Review Board or Board of Adjustment to ensure that both properties considered together
meet the standards of the Watershed Ordinance and that potential owners have record of how the
watershed regulations were applied to the properties .
(K) Calculation of project density . The following requirements shall apply to the calculation of
project density :
(1) Project density shall be calculated as the total built-upon area divided by the total project
area;
(2) A project with "existing development," as that term is defined in 15A NCAC 02B.0621, may
use the calculation method in division (K)(1) or may calculate project density as the difference of total
built-upon area minus existing built-upon area divided by the difference of total project area minus
existing built-upon area.
(3) Expansions to existing development shall be subject to 15A NCAC 02B.0624 except as
excluded in Rule 15A NCAC 02B.0622(1)(d).
(4) Where there is a net increase of built-upon area, only the area of net increase shall be subject
to 15A NCAC 02 B.0624.

(5) Where existing development is being replaced with new built-upon area, and there is a net
increase of built-upon area, only the area of net increase shall be subject to 15A NCAC 02B.0624;
(6) Total project area shall I exclude the following:
(a) Areas below the Normal High Water Line (NHWL); and
(b) Areas defined as "coastal wetlands" pursuant to 15A NCAC 07H.0205.
(7) Projects under a common plan of development shall be considered as a single project for
purposes of density calculation except that on a case-by-case basis, local governments may allow
projects to be considered to have both high and low density areas based on one or more of the
following criteria:
(a) Natural drainage area boundaries;
(b) Variations in land use throughout the project; or
(c) Construction phasing.
(L) Low density projects. In addition to complying with the project density requirements of the Mills
River Watershed Protection Ordinance, low density projects shall comply with the following:
(1) Vegetated conveyances. Stormwater runoff from the project shall be released to vegetated
areas as dispersed flow or transported by vegetated conveyances to the maximum extent practicable.
In determining whether this criteria has been met, the local government shall take into account site-
specific factors such as topography and site layout as well as protection of water quality. Vegetated
conveyances shall be maintained in perpetuity to ensure that they function as designed. Vegetated
conveyances that meet the following criteria shall be deemed to satisfy the requirements of this
division:
(a) Side slopes shall be no steeper than 3:1 (horizontal to vertical) unless it is demonstrated to
the local government that the soils and vegetation will remain stable in perpetuity based on
engineering calculations and on-site soil investigation; and
(b) The conveyance shall be designed so that it does not erode during the peak flow from the
10-year storm event as demonstrated by engineering calculations.
(2) Curb outlet systems. In lieu of vegetated conveyances, low density projects shall have the
option to use curb and gutter with outlets to convey stormwater to grassed swales or vegetated areas.
Requirements for these curb outlet systems shall be as follows:
(a) The curb outlets shall be located such that the swale or vegetated area can carry the peak
flow from the 10-year storm and at a non-erosive velocity;
(b) The longitudinal slope of the swale or vegetated area shall not exceed 5% except where not
practical due to physical constraints. In these cases, devices to slow the rate of runoff and encourage
infiltration to reduce pollutant delivery shall be provided;
(c) The swale's cross section shall be trapezoidal with a minimum bottom width of 2 feet;
(d) The side slopes of the swale or vegetated area shall be no steeper than 3:1 (horizontal to
vertical);
(e) The minimum length of the swale or vegetated area shall be 100 feet; and
(f) Low density projects may use treatment swales designed in accordance with 15A NCAC
02H.1061 in lieu of the requirements specified in divisions (a) through (e) of this division (L)(2).

(M) High density projects. In addition to complying with the project density requirements of the Mills
River Watershed Protection Ordinance, high density projects shall comply with the following:
(1) Stormwater Control Measures (SCMs) shall be designed, constructed, and maintained so that
the project achieves either "runoff treatment" or "runoff volume match" as those terms are defined in
15A NCAC 02B.0621;
(2) For high density projects designed to achieve runoff treatment, the required storm depth shall
be 1 inch. Applicants shall have the option to design projects to achieve runoff volume match in lieu of
runoff treatment;
(3) Stormwater runoff from off-site areas and "existing development ," as that term is defined in
15A NCAC 02B.0621, shall not be required to be treated in the SCM. Runoff from off-site areas or
existing development that is not bypassed shall be included in sizing of on-site SCMs;
(4) SCMs shall meet the relevant MDC set forth in 15A NCAC 02H.1050 through .1062; and
(5) Stormwater outlets shall be designed so that they do not cause erosion downslope of the
discharge point during the peak flow from the 10-year storm event as shown by engineering
calculations.
(N) Options for implementing project density . The Town of Mills River has the following options in
addition to those enumerated in divisions (D) and (E) above, as appropriate.
(1) The Town of Mills River may allow only low density development in its water supply watershed
areas in accordance with this section.
(2) The Town of Mills River may regulate low density single-family detached residential
development using the minimum lot size requirements, dwelling unit per acre requirements, built-upon
area percentages, or some combination of these.
(3) 10/70 option. Outside of WS-I watersheds and the critical areas of WS-II, WS-III, and WS-IV
watersheds, the Town of Mills River may regulate new development under the "10/70 option" in
accordance with the following requirements:
(a) A maximum of 10% of the land area of a water supply watershed outside of the critical area
and within the Town of Mills River's planning jurisdiction may be developed with new development
projects and expansions of existing development of up to 70% built-upon area.
(b) In water supply watersheds classified on or before August 3, 1992, the beginning amount of
acreage available under this option shall be based on the Town of Mills River's jurisdiction as
delineated on July 1, 1993. In water supply watersheds classified after August 3, 1992, the beginning
amount of acreage available under this option shall be based on the Town of Mills River's jurisdiction
as delineated on the date the water supply watershed classification became effective. The acreage
within the critical area shall not be counted towards the allowable 10/70 option acreage;
(c) Projects that are covered under the 10/70 option shall comply with the low density
requirements set forth in division (C) above unless the Town of Mills River allows high density
development, in which case the town may require these projects to comply with high density
requirements;
(d) The maximum built-upon area allowed on any given new development project shall be 70%;
(e) The Town of Mills River may transfer, in whole or in part, its right to the 10/70 land area to
another local government within the same water supply watershed upon submittal of a joint resolution
and approval by the Commission; and
(f) When the water supply watershed is composed of public lands, such as National Forest
land, the Town of Mills River may count the public land acreage within the watershed outside of the

critical area in calculating the acreage allowed under this provision.
(4) New development shall meet the development requirements on a project-by-project basis
except the Town of Mills River may submit ordinances that use density or built-upon area criteria
averaged throughout the Mills River watershed jurisdiction instead of on a project-by-project basis
within the watershed. Prior to approval of the ordinance, the Town of Mills River shall demonstrate to
the Commission that the provisions as averaged meet or exceed the statewide minimum requirements
and that a mechanism exists to ensure the planned distribution of development potential throughout
the local government's jurisdiction within the watershed.
(5) The Town of Mills River may administer oversight of future development activities in single-
family detached residential developments that exceed the applicable low density requirements by
tracking dwelling units rather than percentage built-upon area, as long as the SCM is sized to capture
and treat runoff from 1) all pervious and built-upon surfaces shown on the development plan and 2)
any off-site drainage from pervious and built-upon surfaces, and when an additional safety factor of
15% of built-upon area of the project site is figured in.
(Ord. passed 3-1-2004; Am. Ord. 00013, passed 7-29-2004; Am. Ord. passed 10-13-2005; Am. Ord.
00038, passed 11-21-2006; Am. Ord. 2022-18, passed 12-8-2022)