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City of Lincoln
Floodplain Standards Background Information

Summary


Effective May 25, 2004

Standards generally apply to floodplains or floodprone areas within New Growth Areas - those areas outside the Lincoln city limits and zoned AG Agriculture or AGR Agricultural Residential as of the effective date of the regulations (see map).

Background

In August of 2001, former Mayor Wesely appointed the Mayor's Floodplain Task Force (FPTF), representing a range of stakeholders from the community, to formulate recommendations regarding the development of new floodplain standards. In April of 2003, the FPTF finalized recommendations for: 1) New Growth Areas, and 2) the Existing Urban Area. These recommendations can be found on the City's website at lincoln.ne.gov. The flood standards summarized below are intended to reflect the recommendations of the FPTF for New Growth Areas for the City of Lincoln.

Comprehensive Plan Amendment

  1. Confirms policy assumptions in Comprehensive Plan consistent with recommendations of FPTF.
  2. Adopts series of strategies that reflect policies and principles set forth by FPTF for New Growth Areas.
  3. Speaks to consistency of proposed standards with 2025 Comp Plan land use designations, which identify future urban growth outside of floodplain and designates majority of floodplains as Green Space, Environmental Resources, or Agricultural Stream Corridors.
  4. Strategies include implementation of 'No Adverse Impact' policy, where the action of one property owner does not adversely impact the flooding risk for other properties.
  5. Proposed principles and policy goals apply to both City and County.

Flood Regulations and Standards

  1. Applies to New Growth Areas within Lincoln's jurisdiction (see map).
  2. Includes revisions to multiple documents, including Lincoln Zoning and Subdivision Ordinances, Design Standards, and Drainage Criteria Manual.
  3. Uses best available flood hazard information - standards apply to FEMA-mapped floodplains as well as 'floodprone areas' identified through watershed master plans.
  4. Adopts a 'No Net Rise' standard, technically requiring a hydraulic study to show no rise greater than 0.05' in the 100-year floodplain (outside the floodway) or floodprone areas.
    Exceptions:
    1. Residential non-substantial improvements
    2. Stream crossing structures meeting sequencing standards for minimizing and mitigating impacts
    3. Minor projects with No Rise Certification (require no study)
    4. Approved Preliminary Plats
    5. Public Stream Crossing structures having approved EIS, etc. or design public hearing as of adoption of standards
    6. Dams & stormwater storage facilities
  5. Requires compensatory storage for development in floodplain or floodprone area so that flood storage lost to fill or structures is compensated for by providing replacement storage at 1 to 1 ratio.
    Exceptions: Same as above; stream crossing structures do not have to replace lost storage
  6. Extends requirement for preservation of buffer called 'Minimum Flood Corridor' to stream channels with mapped floodplains and to channels draining less than 150 acres of they have a defined bed and bank. Total buffer width is 60' (30' per side) plus 6x depth of stream.
    Exceptions:
    O&M, channel improvements, stormwater storage, public parks, trails, other public recreational uses allowed to encroach with impacts to storage and vegetation mitigated at a 1.5 to 1 ratio.

    Stream crossing structures - not required to replace lost storage or vegetation at 1.5 to 1 ratio, but must re-vegetate graded areas wherever possible.
  7. Requires all lateral additions to non-residential structures to be protected to flood standards and to meet 'no net rise' and 'compensatory storage' requirements.
  8. Includes revisions to clarify ordinance provisions required by minimum federal and state standards, for administrative purposes, and for consistency between different sections of the code, including application of minimum flood corridors outside the floodplain in the existing urban area.
  9. Recommends and provides some incentives for additional (voluntary) flood management standards -- 'best management practices' and 'best construction practices' to offset impacts to the natural and beneficial functions of floodplains and floodprone areas during site development.

Explanation of Terms:

Floodplain:

The area subject to flooding by a 100-year flood as shown on the Federal Emergency Management Agency (FEMA) maps.

Floodprone Area:

The area subject to flooding by a 100-year flood as determined by studies completed by the City or other government agency, typically as part of a watershed master plan, but not yet incorporated into the FEMA floodplain maps.

Stream Crossing Structures:

Structures used to convey pedestrians, motor vehicles and/or utilities across drainageways. Stream crossing structures are composed of the structure, abutments, guard rails, fill, and other structural appurtenances that are generally perpendicular to the conveyance of flow within the floodplain or floodprone area.

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Floodplain Standards Background Information