SENSITIVE LANDS
Boise City Code § 11-04-05
in effect11-04-05: SENSITIVE LANDS:
1. Airport Influence Area Standards: All development within the Airport Influence Overlay district shall comply with the standards in Section 11-02-07.3.D, AI-O Airport Influence Area Overlay.
2. Boise River System Standards: All development within the Boise River System Overlay district shall comply with the standards in Section 11-02-07.3.E, BR-O: Boise River System Overlay.
3. Flood Hazard Standards: All development within the Flood Protection Overlay district shall comply with the flood hazard standards in Section 11-02-07.3.F, FP-O Flood Protection Overlay.
4. Hillside Development Standards: All development within the Hillside Development Overlay district shall comply with the standards in Section 11-02-07.3.G, HS-O: Hillside Development Overlay.
5. Wildland Urban Interface Standards: All development within the Wildland Urban Interface Overlay district shall comply with the standards in Section 11-02-07.3.H, WUI-O: Wildland Urban Interface Overlay.
6. Foothills Development Standards:
A. Purpose: The purpose of this Section 11-04-05.6 is to implement residential subdivision density and design elements of the Comprehensive Plan in the Foothills Planning Area. It is also designed to protect and promote preservation of contiguous areas of Foothills open space that contain important and significant natural and cultural resource values, as identified in the Comprehensive Plan and this Code.
B. Applicability:
(1) This Section 11-04-05.6 shall apply to all proposed developments in the Foothills Planning Area at the time an Annexation is proposed and/or a Zoning Map Amendment is requested.
(2) The standards of this Section 11-04-05.6 also apply to developments within the Hillside Development Overlay as described in Section 11-02-07.3.G, HS-O: Hillside Development Overlay.
C. General Requirements:
(1) In addition to application materials otherwise required for an annexation or rezoning, applications for development in the Foothills Planning Area shall include materials required for a Hillside and Foothill Areas Development Permit, and where applicable, a Floodplain Permit.
(2) Upon annexation the buildable areas shall be zoned as R-1A, and shall be required to comply with the provisions of this Section 11-04-05 .6, unless City Council determines that some buildable areas not including steep slopes or sensitive lands shall be zoned R-1B in return for the zoning of other A-1 for preservation as open space.
(3) Developments shall be required to connect to municipal water and sewer services and participate in other municipal service districts as applicable.
D. Permitted Development Densities:
(1) Additional Dwelling Units Permitted:
(a) In return for the preservation of open space, applicants shall be permitted to develop additional dwelling units beyond those permitted in the existing base zoning district(s) pursuant to the formula in Table 11-04.6 .
(b) These provisions do not increase the area of the site that may be developed, but increase the number of units that may be developed within the same buildable area. Additional dwelling units may be added to the density base units without the requirement for additional open space preservation.
(c) The number of additional dwelling units permitted is based upon the ratio of (i) buildable area to be preserved as open space to (ii) the buildable area to be developed.
(d) Additional dwelling units are allowed based on the percentage of built area occupied and open space dedicated as shown in Table 11-04.6 : Density Bonus Formula, provided that the formula is unchanged. If the numbers for the applicant's built area fall in between the numbers provided in the left-hand column, the density bonus will be calculated based on built area shown in the table that is closest to, but higher than, the applicant's built area. For example, if the applicants project has a built area equal to 73 percent of the site area, the density bonus will be based on the factors shown for a project with a built area equal to 75 percent.
(e) The density formula may be adjusted to allow density transfers from non-contiguous parcels after a Transfer of Development Rights (TDR) ordinance is in effect.
TABLE 11-04.6: DENSITY BONUS FORMULA
BUILT AREA (PERCENT) | OPEN SPACE DEDICATED (PERCENT) | DENSITY BONUS (UNITS/ACRE) | BUILDABLE AREA ON 100 ACRES AFTER OPEN SPACE SET- ASIDE (ACRES) | NUMBER OF BONUS UNITS
TABLE 11-04.6: DENSITY BONUS FORMULA
BUILT AREA (PERCENT) | OPEN SPACE DEDICATED (PERCENT) | DENSITY BONUS (UNITS/ACRE) | BUILDABLE AREA ON 100 ACRES AFTER OPEN SPACE SET- ASIDE (ACRES) | NUMBER OF BONUS UNITS
75 | 25 | 0.5 | 75.0 | 38
69 | 31 | 0.75 | 68.8 | 52
63 | 37 | 1.0 | 62.5 | 63
56 | 44 | 1.25 | 56.3 | 70
50 | 50 | 1.5 | 50.0 | 75
44 | 56 | 1.75 | 43.8 | 77
38 | 62 | 2.25 | 37.5 | 84
31 | 69 | 3.0 | 31.3 | 94
25 | 75 | 4.0 | 25.0 | 100
(2) Eligible Preserved Open Space:
(a) Preserved open space eligible for a density bonus based on Table 11-04.6 : Density Bonus Formula, shall comply with the following requirements:
i. The open space shall be classified as priority open space in Subsection (4) below.
ii. The open space shall be at least one acre in size and shall have an average width of at least 30 feet.
iii. The open space shall not have a slope greater than 25 percent.
(b) Public rights-of-way that connect development pockets and provide access to public open space may be included in the density calculation for open space.
(c) Roads within a development pocket and other public rights-of way that have dwelling units fronting or siding onto them shall not be included in density calculations for open space.
(3) Ineligible Preserved Open Space:
(a) The following shall not be considered as preserved open space in the density bonus calculation, except as may be provided in Subsection (4):
i. Urban development such as club houses, tennis courts, swimming pools, dirt bike tracks, golf driving ranges, and similar uses that dramatically alter land from its natural state; and
ii. Commercial land uses.
(b) Park sites internal to a subdivision or development may only be included as eligible open space when they are retained in a primarily natural condition and include a significant opening from the subdivision or development into a larger designated open space outside the subdivision or development.
(4) Priority Open Space:
(a) Some areas of the Foothills have a combination of characteristics that cause them to be considered worthy of special incentives for preservation, even if they do not meet those size, slope, or dimensional standards to qualify as open space eligible for a density bonus under Subsection (2) above. When these areas are identified on a property and proposed for preservation, the PZC may classify them as priority open space and allow all or a portion of them to qualify for the approval of additional dwelling units.
(b) General Eligibility Criteria: Priority open space shall include at least four of the following characteristics to be eligible for a density bonus:
i. Wetlands;
ii. Riparian areas;
iii. Rare plant communities;
iv. Critical deer and elk winter range and migration corridors;
v. Potential Public Preservation Sites as documented by the HPC;
vi. Unique geologic or visual features;
vii. Archeological or other historic sites;
viii. Designated trails and trailheads in the Ada County Ridge to Rivers Pathway Plan;
ix. Other public trails and trailheads as approved by the Parks and Recreation Board;
x. Areas adjacent to publicly held open spaces or areas that have been identified for consideration as permanent public open space; or
xi. Areas that have been dedicated to or acquired by a public agency through a discounted sale.
(c) Additional Criteria for Steeply Sloped or Fragmented Open Space
i. Preservation of priority open space in steeply sloped areas or in fragmented pieces shall only be eligible for approval of additional dwelling units if it meets the following criteria, as determined by the Planning and Zoning Commission after receiving input from the Idaho Department of Fish and Game, the Parks and Recreation Board, and other public agencies with expertise in the issue at hand in determining the proper amount to be allowed to be set aside in return for a density bonus.
A. Public access is provided to the priority open space;
B. The open space protects important vegetation, terrain, or scenic views and vistas that could be damaged or destroyed from an allowed use such as mining, logging, grazing, or construction of utilities or infrastructure;
C. The open space links interspersed eligible areas into a more biologically complete and continuous wildlife corridor; or
D. The open space is dedicated to or acquired by a public agency through a discounted sale.
ii. Links type golf courses may be permitted in designated preserved open space, provided that the intervening spaces are maintained in a primarily natural condition. Golf courses shall use native plants, and natural contours shall be left intact. Parking lots, club houses, driving ranges, maintenance facilities, and similar golf related uses shall not be counted as open space contributory to the density bonus. Designated trails and park sites shall be preserved in or around the golf course.
(5) Design Standards:
(a) General Standards:
i. Residential uses shall be clustered in development pockets rather than scattered throughout the property.
ii. Development pockets shall comply with design principles in the Comprehensive Plan concerning clustering, environmental protection, open space conservation, and scenic and aesthetic goals.
iii. Gated entrances are prohibited due to the potential for such limited access to restrict or delay emergency response.
iv. Designated open space shall be linked to the maximum extent practicable.
v. Disturbance of the land shall be minimized, and development shall be avoided in areas that would require excessive grading, cut, and fill.
vi. Road and trail access to adjacent properties shall be provided to prevent landlocked parcels or breaks in the trail systems, and to provide the opportunity for future connectivity.
vii. Roads and infrastructure shall not cross designated open space, floodways, wetlands, and areas of high wildlife habitat value to the maximum extent practicable.
(b) Standards for Trails: Trails that comply with the following design standards shall be provided as part of the subdivision or development.
i. The Ada County Ridge-To-Rivers Pathway Plan shall guide trail locations.
ii. Public access to trails within and contiguous to the development shall be provided, unless no contiguous or intersecting public trails exist or are proposed, in which case private trails may be established through the open space, provided that the design preserves the natural character and wildlife habitat value.
iii. Trail design shall preserve the natural scenic and wildlife habitat values to the maximum extent practicable.
iv. Public trails shall be secured through dedication, easement, or other such binding mechanism, and shall be shown on the Subdivision Plat.
(c) Standards for Preserved Open Space: Priority open space shall be preserved and managed to comply with the following standards.
i. Contiguous areas of open space within the development and adjacent properties shall be preserved by aligning them along common corridors to the extent possible.
ii. Indigenous plant species, except for noxious and invasive weeds, shall be maintained undisturbed to the extent possible.
iii. Areas of highest wildlife habitat value and migration corridors in designated wildlife habitat identified in the Comprehensive Plan shall be preserved.
iv. Unique geologic and historic features defined as heritage sites, and sites designated for historic preservation by city, state, and federal agencies shall be preserved.
v. Landslide areas and areas with unstable soils shall not be developed.
vi. Fencing shall not encroach into preserved open space.
vii. Agricultural or utility uses may be permitted in open spaces, including livestock grazing, community gardens, or irrigation ponds, and only including those buildings, structures, and necessary appurtenances required by those uses, such as dams and irrigation or drainage systems. These use exceptions shall comply with the policies of the Foothills Policy Plan, shall be shown on the site plan, and shall not degrade the value of the permanent open space.
viii. Fencing shall not encroach into preserved open space.
(d) Grading and Building Disturbance Envelopes:
i. Building envelopes may be required to be shown on the final site plan, and if required shall be recorded or referenced in the notes on the Final Plat.
ii. Slopes greater than 25 percent shall be shown on the Conditional Use Permit site plan with a disturbance envelope that defines the area outside of which no grading will be allowed.
(6) Ownership and Maintenance of Open Space:
(a) Open space areas may be owned and maintained:
i. By and for the use of the Homeowners' Association of the project of which it is a part;
ii. By any neighboring Homeowners' Association with abutting preserved open space;
iii. By an organization managing adjacent lands held as permanent open space and jointly maintained under a Development Agreement with the City;
iv. By the City, if the open space is dedicated or sold to the City after a recommendation of approval to accept such lands by the Board of Parks and Recreation, Planning and Zoning Commission, or other public agency, or a private land trust for open space uses, as noted in a Development Agreement approved by City Council; or
v. Through other open space preservation strategies under sole or joint ownership, such as deed restrictions, or conservation easements, as executed when approved by the City.
(b) Where the goals and policies of adopted plans specify the need for public trails or open space, easements for public lands or trails may be required. Trails or open spaces may be held in private ownership subject to an easement, or may be purchased by the City, or dedicated by the landowner(s) to the City.
(c) The City will accept no responsibility for the costs of maintenance of open space or recreational facilities unless the Board of Parks and Recreation, PZC, and the City Council specifically approve that responsibility in a written agreement. (Ord. 27-23, 7-18-2023, eff. 12-1-2023; amd. Ord. 43-23, 12-5-2023; Ord. 25-25, 6-24-2025)
Source: Boise City, Idaho, City Code and City Charter (American Legal Publishing, codelibrary.amlegal.com)URL: https://codelibrary.amlegal.com/codes/boise_id/latest/boise/0-0-0-67596Fetched: 11/1/2026