Levee setbacks at the 24th East Pointbar Site will produce low levels of floodplain inundation at high
frequency events. The total probable area of inundation of the Site is estimated to be 94,900 square feet
(2.2 acres). Areas of inundation for 2-year and 5-year events are estimated to be 70,390 square feet
(1.6 acres) and 298,527 square feet (6.9 acres) respectively. Levee setbacks at Site 28 would contribute
moderately to flood storage (Table E-28).
Sixty-six percent of the Site is located within the 'severe' channel migration zone (GeoEngineers 2003).
The total area of the Site is 400,070 square feet (9.2 acres), of which 262,307 square feet (6 acres and 66% of
the site) occupy lands delineated as having severe (high) channel migration potential and 96,178 square feet
(2.2 acres, and 24% of the Site) occupy lands delineated as having moderate channel migration potential.
The proposed levee setback project at Site 28 has low potential to promote increased channel complexity and
multi-channel reaches. (Table E-28).
Current land cover of the Site consists of mature deciduous and coniferous trees, invasive weeds such as
Himalayan blackberry (Rubus discolor), grasses and forbs. Reconnection of the White River to the Site
would be expected to moderately promote large woody debris recruitment, pool formation, and connectivity
to side channels (Table E-28).
The sediment transport capacity and storage capacity would not be expected to change during high or low
frequency events (5-year and 25-year steady state flows respectively) with minimal downstream impacts.