| Distance from LB BM (ft) | Elevation, in feet | ||
|---|---|---|---|
| July 1962 | June 1963 | July 1968 | |
| 0 - BM 2 | 93.03 | 93.03 | 93.03 |
| 0 | 92.58 | 92.63 | 92.62 |
| 5 | 92.33 | 92.38 | 92.30 |
| 10 | 91.98 | 92.02 | 92.00 |
| 15 | 91.65 | 91.71 | 91.67 |
| 20 | 91.44 | 91.44 | 91.43 |
| 25 | 91.16 | 91.26 | 91.21 |
| 30 | 90.84 | 90.83 | 90.90 |
| 33.5 | 90.63 | ||
| 35 | 90.50 | 90.49 | 90.43 |
| 37.5 | 89.76 | 89.72 | |
| 39.4 | 89.32 | 89.20 | |
| 40 | 89.03 | 89.07 | 89.11 |
| 40.7 | 89.02 | ||
| 41.4 | 89.16 | ||
| 42.5 | 89.28 | ||
| 43.6 | 89.53 | ||
| 44 | 89.62 | ||
| 45 | 89.78 | 89.82 | 89.78 |
| 50 | 89.52 | 89.59 | 89.54 |
| 55 | 89.21 | 89.32 | 89.22 |
| 60 | 89.01 | 89.12 | 89.05 |
| 65 | 88.73 | 88.76 | 88.80 |
| 70 | 88.54 | 88.59 | 88.70 |
| 75 | 88.23 | 88.25 | 88.23 |
| 80 | 88.01 | 88.04 | 88.04 |
| 85 | 87.80 | 87.88 | 87.78 |
| 90 | 87.42 | ||
| 90.6 | 87.36 | 87.44 | 87.43 |
| 90.6 - BM 3 | 87.84 | 87.84 | 87.85 |
Explanation of Terms
LB BM description: LB means left bank, facing downstream. LB BM is the left-bank bench mark, or reference point. The term "bench mark (BM)" refers to a 4-foot steel rod, 1/2 inch diameter, driven into the ground and protruding about 6 inches. All bench marks have a brass identification tag attached which is imprinted with the bench-mark description and elevation.
LB BM and RB BM elevation: Elevations, in feet, are referenced to an arbitrary elevation of 100.00 feet at the top of BM-1. The adding of 3700 feet gives the approximate elevation above sea level.
Distance from LB BM: Distance, in feet, from left-bank bench mark toward right-bank bench mark.
Elevation: Bench mark elevations refer to the tops of the bench marks, and other elevations refer to the ground surface. Yearly variations in elevation for a given position on a sloping surface may not necessarily imply erosion or deposition of that amount because slight leeway in lateral placing of level rod gives variation in elevation. However, for flat or nearly flat surfaces, such as the channel bed, variations probably record actual changes. See also LB BM and RB BM elevation.