Determining Ordinary High Water
Corps of Engineers and Dept. of State Lands Jurisdictional Determinations on non-Tidal
Waterways ACEC
Frannie Brindle 503 986-3370Natural Resource Unit Manager, ODOT Technical Services
Dept. of State Lands and Corps of Engineers
DSL and CORPS of ENGINEERS’ REGULATORY JURISDICTION
Section 404 and State R/F LawSection 404 and State R/F Law
OHW is Defined by Field Characteristics
Drift material (or wrack) in fence?
Clear line impressed along shore?
Antelope Creek, Jackson Co. March 2006
Field Characteristics
Culvert staining–not appropriate for determining fish passage design criteria
Relation to Other ‘Lines’• 2-year flood elevation
– Calculated based on modeling – OHW is usually lower on the bank than the 2-year
• Bank full stage– Often used interchangeably with OHW in literature– Channel forming flows – Defined by DSL as the two-year recurrence interval flood
elevation
• Edge of Water• Top of bank
– Easily identifiable on some streams– OHW is usually below the top of the bank
Context
In-water work timing
Resource Impacts
Fish Passage Design
Procedures• Flag OHW in field (flag only one side of stream if
access is limited and project line to the other side in CAD)
• Use painted stakes or flags where possible
• Take photos up- and down-stream showing flag placement
Procedures (cont)• Complete form:
– OHW field characteristics observed– If 2-year used instead, should be stated
• Develop site sketch showing flag locations, photo-points
• Final Documentation includes OHW Determination Form, Photos, Site Sketch
Completing the Form
2
Sample Site Sketch
Low hanging vegetation- willows, other riparian
Steep bank- visible indicators
N
1
3
4Elevation point
flow
P1
P2, 3