Boise River System Overlay

The purpose of the BR-O district is to:

(a) Ensure protection from flooding;
(b) Allow for conveyance of the 100 year flood flow to lessen damage to public and private properties;
(c) Preserve, protect, and enhance the abundance and diversity of fish, wildlife, and riparian vegetation native to the Lower Boise River and its floodplain, and that of its tributaries;
(d) Control runoff and pollution so as to protect water quality of the river and its tributaries;
(e) Protect the Boise River as a public asset to the city and a major amenity for its citizens;
(f) Maintain the Boise River Greenbelt;
(g) Ensure that development is designed to enhance and protect rivers including riparian areas, fish, wildlife, and recreational values; and
(h) Provide and maintain continuous public access to and along the river including appropriate facilities for parking of bikes and motor vehicles.

See More About Sensitive Lands Overlay Districts

Regulations and Uses (Table 11-02.37)










Class AYesYesYesYesYes
Class BYesYesYesYesYes
Class CYesYesNoYesYes

Map and Boundaries


The Boise River System Overlay district shall include the following areas:

i. Floodway and Floodway Fringe Overlay Districts
Lands within the 100 year floodplain boundaries adjacent to the Boise River, including lands designated within the Floodway (F) and Floodway Fringe
(FF). These boundaries adjacent to the Boise River are determined by the FEMA Flood Boundary and Floodway Map. A copy of this map is available at the Planning and Development Services Department and on the City’s website. The Planning Director, with recommendation from the City Engineer, shall provide boundary interpretations where necessary. These areas are subject to the standards in Section 11-02-07.3.F FP-O Flood Protection Overlay and the standards in Subsections (4) – (10), below.
ii. Alluvial Overlay District
Tributary floodplains and associated alluvial fans (AO zones) standards are addressed in Section 11-02-07.3.F, FP-O Flood Protection Overlay.

Boundary Descriptions

Floodway (F) District Boundary

The Floodway District shall have the boundaries as follows: The Channel of a river or other watercourse and the adjacent land areas that shall be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation more than one foot, as shown in the Flood Insurance Study for Boise City, Idaho.

Flood Fringe (FF) District Boundary

The Floodway Fringe District shall have boundaries as follows: The area between the floodway boundary and the boundary of the 100 Year Flood.

Area of Shallow Flooding (ASF) District Boundary

The Area of Shallow Flooding District shall have boundaries as area shown on the Flood Insurance Rate Map as an AO zone with base flood depths from one to three feet where a clearly defined channel does not exist, where the path of flooding is unpredictable and indeterminate, and where velocity flow may be evident.

A, B, and C Lands and Waters Classifications

The BR-O district includes lands and waters that provide natural resource functions and values including the preservation of fish and wildlife amenities shall be classified as "Class A, B, or C lands and waters."

Class A Lands and Waters - Extremely Important for Preservation

Class A lands and waters provide extremely important habitats for fish and wildlife and for flood control and protection. The objective is to preserve and protect these areas for their benefits to fish and wildlife in general and to protect Bald Eagle, Great Blue Heron, trout, and waterfowl habitats in particular. These areas include, but are not limited to:

i. Floodways;
ii. Areas with a high degree of plant community diversity;
iii. Black cottonwood riparian plant communities;
iv. Riparian forests;
v. Scrub-shrub wetlands;
vi. Emergent wetlands within the floodplain (exclusive of working irrigation canals);
vii. A 300 foot radius around Great Blue Heron rookeries;
viii. Eagle winter habitat that includes lands within 200 feet of the 6500 cubic feet per second (c.f.s.) line, as determined by the Public Works Department based on their monitoring of annual flows, east of Walnut Street on the north side of the river and east of Phase 4 of the River Run Subdivision on the south, and forested wetlands east of these points;
ix. Lands within the riparian setback lands and waters;
x. The banks of side channels and tributary stream areas within the jurisdiction of this overlay district;
xi. Islands within the river;
xii. Trout spawning waters;
xiii. Riparian areas of tributary streams within the jurisdiction of this overlay district including channels that convey floodwaters and areas that meet the definition of wetlands; and
xiv. Lands currently identified as the Barber Pool Conservation Area.

Class B Lands and Waters - Moderately Important for Preservation

Class B lands and waters provide good potential for improvements to natural resource functions and values. Development should improve natural resource functions and values and avoid negative impacts. Class B lands and waters include, but are not limited to:

i. Agricultural lands;
ii. Gravel pit ponds and small lakes; and
iii. Intermittent tributary streams.

Class C Lands and Waters - Least Important for Preservation

Class C lands and waters provide limited fish and wildlife habitat. Development should provide landscaping and habitat improvements. These areas include, but are not limited to:

i. Public and private parks where current uses preclude enhancement of fish and wildlife habitat;
ii. Diversion dams;
iii. Residential and commercial developments;
iv. Lands surrounding gravel ponds;
v. Subdivided properties;
vi. Former industrial areas; and
vii. Vacant lands in urban centers.

Other Applicable Code Considerations

  • Setbacks
  • Allowed Uses and Improvements
  • Standards Applicable to All Development Within the BR-O District
  • Additional Standards Applicable to Class A Lands and Waters
  • Additional Standard Applicable to Class B Lands and Waters
  • Additional Standard Applicable to Class C Lands
  • Conditions for Permits
  • Mitigation
  • Enhancement

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