North Albany Floodplain Study Overview
- Updated on Tuesday, October 2, 2012, 7:33 pm
In early 2010 the City retained Pacific Water Resources (now AMEC Earth and Environmental) to model the floodplain of the Willamette River in North Albany. The study was initiated because the current Federal Emergency Management Agency (FEMA) floodplain maps for North Albany appeared to be inaccurate. The most significant inaccuracy was an unmapped floodway, which was identified through review of past development proposals that were either ultimately denied or have since expired. In order to adequately review future development proposals the City believed it was important to have a more accurate understanding of floodplain characteristics throughout North Albany. In addition, by having this study completed in advance of development proposals the development community will know what challenges might exist on an existing parcel prior to investing in predevelopment activities.
AMEC concluded their study in July 2011. The study verified that there was a significant unmapped floodway through North Albany. This floodway is essentially an overflow channel from the Willamette River. It is estimated that during a 100-year flood event approximately 5,600 cubic feet per second (cfs) of water flows through this floodway at a maximum speed in excess of five feet per second. To put that amount of water in perspective, it is typically what flows in the Willamette River itself in September. At five feet per second, water with very little depth can apply enough force to push a car off of the road.
The study also unexpectedly identified significant differences in the amount of flooding throughout the study area. These differences were seen in both the extents and depths of flooding. When compared to FEMA’s most recent DFIRM floodplain maps, the study identified approximately 190 acres of property mapped as being in the floodplain that should not be and approximately 125 acres of property that should be shown in the floodplain, that is not. Differences in the depths of flooding ranged from as much as five feet less than what FEMA predicts to as much as three feet more than FEMA predicts.
It is important to note that these study results have not yet been reviewed and approved by FEMA. The City Council has asked staff to inform North Albany residents about the study results in order to make sure residents are aware of the potential flooding risks on their property.
Following the open house scheduled for 7:00 p.m. on November 8, 2011, at North Albany Middle School, the City will submit the study to FEMA for review and potential map amendments. FEMA can agree, request that the City provide additional information and request modification, or completely disagree with the City’s study results. Because the FEMA review has not yet occurred, the results presented in this website are not final. Additional public outreach activities will occur in the future as required during the FEMA review process.
FEMA recommends using both the adopted FEMA maps and the study results (regulate to the worst case) for reviewing new development applications until FEMA has completed their review and updated the maps. Council will be considering Albany Development Code amendments to adopt FEMA’s recommended approach and is very interested in hearing from North Albany residents prior to making any decisions. Future public hearings will be held for further consideration of FEMA’s recommendation.
In addition to this general overview, this website contains:
- Definitions of floodplain terminology,
- Aerial photos of past flood events,
- Maps of the study results, compared to the currently adopted FEMA maps
- A question and answer section,
- Technical information on the floodplain modeling approach, and
- A description of potential flood insurance rate implications
Albany’s current floodplain development regulations are found in Article 6 of the Albany Development Code.
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