A. 
The purpose of these standards is to reduce the risk of flooding, prevent or reduce risk to human life and property, and maintain the functions and values of floodplains, such as allowing for the storage and conveyance of stream flows through existing and natural flood conveyance systems.
B. 
This section establishes a flood management area overlay zone, which is delineated on the flood management area map incorporated by reference as a part of this chapter.
(Ord. 389 § 1(Exh. A), 2009)
A. 
The flood management areas mapped include land contained within the 100 year floodplain, flood area and floodway as shown on the Federal Emergency Management Agency flood insurance maps.
B. 
The standards that apply to the flood management areas apply in addition to local, state or Federal restrictions governing floodplains or flood hazard areas, including the standards in Chapter 15.24, Flood Damage Prevention.
(Ord. 389 § 1(Exh. A), 2009)
A. 
Uses Permitted Outright.
1. 
Excavation and fill required to plant any new trees or vegetation;
2. 
Restoration or enhancement of floodplains, riparian areas, wetland, upland and streams that meet Federal and State standards.
B. 
Conditional Uses. All uses allowed in the base zone or existing flood hazard overlay zone are allowed in the flood management overlay zone subject to compliance with the development standards of this section.
C. 
Prohibited Uses.
1. 
Any use prohibited in the base zone or existing flood hazard overlay zone (Chapter 15.24, Flood Damage Prevention);
2. 
Uncontained areas of hazardous materials as defined by the department of environmental quality.
(Ord. 389 § 1(Exh. A), 2009)
[1]
Editor's Note: Ord. 589, which amended this section with regard to Cottage Clusters, was remanded by the courts and all amendments were removed at request of the City.
A. 
All development, excavation and fill in the floodplain shall conform to the following balanced cut and fill standards.
1. 
No net fill in any floodplain is allowed. All fill placed in a floodplain shall be balanced with at least an equal amount of soil material removal.
2. 
Excavation areas shall not exceed fill areas by more than 50% of the square footage.
3. 
Any excavation below bankful stage shall not count toward compensating for fill.
4. 
Excavation to balance a fill shall be located on the same parcel as the fill unless it is not reasonable or practicable to do so. In such cases, the excavation shall be located in the same drainage basin and as close as possible to the fill site, so long as the proposed excavation and fill will not increase flood impacts for surrounding properties as determined through hydrologic and hydraulic analysis.
5. 
For excavated areas identified by the City to remain dry in the summer, such as parks or mowed areas, the lowest elevation of the excavated area shall be at least six inches above the winter "low water" elevation, and sloped at a minimum of two percent towards the protected water feature. One percent slopes will be allowed in smaller areas.
6. 
For excavated areas identified by the City to remain wet in the summer, such as a constructed wetland, the grade shall be designed not to drain into the protected water feature.
7. 
Minimum finished floor elevations and the bottom floor of septic tanks must be at least one foot above the design flood height or highest flood of record, whichever is higher, for new habitable structures in the flood area.
8. 
Short-term parking in the floodplain may be located at an elevation of no more than one foot below the 10 year floodplain so long as the parking facilities do not occur in a water quality resource area. Long-term parking in the floodplain may be located at an elevation of no more than one foot below the 100 year floodplain so long as the parking facilities do not occur in a water quality resource area.
9. 
Temporary fills permitted during construction shall be removed.
10. 
New culverts, stream crossings and transportation projects shall be designed as balanced cut and fill projects or designed not to significantly raise the design flood elevation. Such projects shall be designed to minimize the area of fill in flood management areas and to minimize erosive velocities. Stream crossings shall be as close to perpendicular to the stream as practicable. Bridges shall be used instead of culverts wherever practicable.
11. 
Excavation and fill required for the construction of detention facilities or structures, and other facilities, such as levees, specifically shall be designed to reduce or mitigate flood impacts and improve water quality. Levees shall not be used to create vacant buildable lands.
B. 
Land divisions and other proposed new development, including manufactured home parks, shall be reviewed to determine whether such proposals will be reasonably safe from flooding. If a land division or other development proposal is in a flood-prone area, any such proposals shall be reviewed to assure that all proposals shall:
1. 
Be consistent with the need to minimize flood damage;
2. 
Have public utilities and facilities such as sewer, gas, electrical and water systems located and constructed to minimize flood damage; and
3. 
Have adequate drainage provided to reduce exposure to flood damage.
C. 
Where base flood elevation data has not been provided or is not available from another authoritative source, it shall be generated for subdivision proposals and other proposed developments which contain at least 50 lots or five acres (whichever is less).
(Ord. 389 § 1(Exh. A), 2009; Ord. 545 § 1, 2019)
A. 
The purpose of this section is to ensure that compliance with Chapter 16.35 does not cause unreasonable hardship. To avoid such instances, the requirements of Chapter 16.35 may be varied. Variances are also allowed when strict application of Chapter 16.35 would deprive an owner of all economically viable use of land, pursuant to Section 16.71.040, Class B variance.
B. 
This section applies in addition to the standards governing proposals to vary the requirements of the base zone.
C. 
The Community Development Director shall provide the following notice of variance applications:
1. 
Upon receiving an application to vary the requirements of Chapter 16.35, the Planning Official shall provide notice of the request to all property owners within 300 feet; to Metro; to any affected neighborhood or community planning organization recognized by the City and whose boundaries include the property; and to any watershed council recognized by the Oregon Watershed Enhancement Board and whose boundaries include the property.
2. 
Within seven days of a decision on the variance, the Planning Official shall provide notice of the decision to all property owners within 300 feet; to Metro; to any affected neighborhood or community planning organization recognized by the City and whose boundaries include the property; to any watershed council recognized by the Oregon Watershed Enhancement Board and whose boundaries include the property; and to any other person required to receive notice of such a decision under State law.
D. 
Hardship Variance. Variances to avoid unreasonable hardship caused by the strict application of Chapter 16.35 are permitted subject to the criteria set forth in this section. To vary from the requirements of Chapter 16.35, the applicant must demonstrate the following:
1. 
The variance is the minimum necessary to allow the proposed use or activity;
2. 
The variance does not increase danger to life and property due to flooding or erosion;
3. 
The impact of the increase in flood hazard, which will result from the variance, will not prevent the City from meeting the requirements of Chapter 16.35. In support of this criteria the applicant shall have a qualified professional engineer document the expected height, velocity and duration of floodwaters, and estimate the rate of increase in sediment transport of the floodwaters expected both downstream and upstream as a result of the variance;
4. 
The variance will not increase the cost of providing and maintaining public services during and after flood conditions so as to unduly burden public agencies and taxpayers;
5. 
Unless the proposed variance is from mitigation under Section 16.34.075(D)(1) (mitigation plan), the proposed use will comply with those standards, as applicable; and
6. 
The proposed use complies with the standards of the base zone.
E. 
Variance Conditions. The Planning Official may impose such conditions as are deemed necessary to limit any adverse impacts that may result from granting relief.
(Ord. 389 § 1(Exh. A), 2009; Ord. 539 § 1, 2018)
A. 
The purpose of this section is to provide a process for amending the flood management areas map to correct the location flood management area overlay zones.
B. 
Map Corrections.
1. 
Within 90 days of receiving information establishing a possible error in the existence or location of a protected flood management area overlay zone, the City shall provide notice to interested parties of a public hearing at which the City will review the information;
2. 
The City shall amend the flood management areas map if the information demonstrates:
a. 
That the water feature no longer exists because the area has been legally filled, culverted or developed prior to the adoption of this chapter, or
b. 
The boundaries of the flood management area overlay zone have changed since adoption of the flood management areas map.
(Ord. 389 § 1(Exh. A), 2009)
The degree of flood protection required by Chapter 16.35 is considered reasonable for regulatory purposes and is based on scientific and engineering considerations. Larger floods can and will occur on rare occasions. Flood heights may be increased by manmade or natural causes. Chapter 16.35 does not imply that land outside the areas of special flood hazards or uses permitted within such areas will be free from flooding or flood damage. Chapter 16.35 shall not create liability on the part of the City or County, any officer or employee of the City or County, or the Federal Insurance Administration, for any damages that result from reliance on flood management sections of this chapter or any administrative decision lawfully made hereunder.
(Ord. 389 § 1(Exh. A), 2009)
Development proposals that are subject to the provisions of Chapter 16.35 will require an environmental review permit application. Environmental Review Permits will be reviewed through a Type II procedure, pursuant to Section 16.61.030.
(Ord. 389 § 1(Exh. A), 2009)