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