This historic truss bridge is listed in the US National Register of Historic Places, and the NGS database. BM BL0378 is located on the southeast wingwall abutment on the old highway bridge (yes, you WILL have to squeeeeeeze through a fence to get to it), about 6-8 inches above the road.
From the NGS datasheet: (
visit link)
"BL0378 DESIGNATION - K 896
BL0378 PID - BL0378
BL0378 STATE/COUNTY- TX/LIBERTY
BL0378 USGS QUAD - LIBERTY
BL0378
BL0378 *CURRENT SURVEY CONTROL
BL0378 ___________________________________________________________________
BL0378* NAD 83(1986)- 30 03 26. (N) 094 49 00. (W) SCALED
BL0378* NAVD 88 - 10.314 (meters) 33.84 (feet) ADJUSTED
BL0378
BL0378
BL0378_MARKER: DB = BENCH MARK DISK
BL0378_SETTING: 31 = WINGWALL CURB
BL0378_STAMPING: K 896 1943
BL0378_STABILITY: D = MARK OF QUESTIONABLE OR UNKNOWN STABILITY
BL0378
BL0378 HISTORY - Date Condition Recov. By
BL0378 HISTORY - 1943 MONUMENTED CGS
BL0378 HISTORY - 1972 GOOD NGS
BL0378 HISTORY - 1987 GOOD NGS
BL0378 HISTORY - 1988 GOOD USPSQD
BL0378 HISTORY - 1989 GOOD USPSQD
BL0378 HISTORY - 1990 GOOD USPSQD
BL0378 HISTORY - 19960801 GOOD USPSQD
BL0378
BL0378 STATION DESCRIPTION
BL0378
BL0378''DESCRIBED BY NATIONAL GEODETIC SURVEY 1972
BL0378''1.3 MI W FROM LIBERTY.
BL0378''ABOUT 1.3 MILES WEST ALONG U.S. HIGHWAY 90 FROM THE EAST JUNCTION OF
BL0378''STATE HIGHWAY 146 AT LIBERTY, 13 1/2 FEET SOUTH OF THE CENTER LINE OF
BL0378''THE EASTBOUND LANE OF THE HIGHWAY, SET IN THE CONCRETE CURBING OF THE
BL0378''SOUTHEAST WING WALL FOR THE EASTBOUND TRAFFIC OF HIGHWAY BRIDGE OVER
BL0378''TRINITY RIVER, 3 1/2 FEET EAST OF THE EAST END OF THE BRIDGE AND ABOUT
BL0378''1 FOOT ABOVE THE LEVEL OF THE HIGHWAY.
BL0378
BL0378 STATION RECOVERY (1987)
BL0378
BL0378''RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1987
BL0378''RECOVERED IN GOOD CONDITION.
BL0378
BL0378 STATION RECOVERY (1988)
BL0378
BL0378''RECOVERY NOTE BY US POWER SQUADRON 1988 (CTA)
BL0378''RECOVERED IN GOOD CONDITION.
BL0378
BL0378 STATION RECOVERY (1989)
BL0378
BL0378''RECOVERY NOTE BY US POWER SQUADRON 1989 (MA)
BL0378''RECOVERED IN GOOD CONDITION.
BL0378
BL0378 STATION RECOVERY (1990)
BL0378
BL0378''RECOVERY NOTE BY US POWER SQUADRON 1990 (CTA)
BL0378''RECOVERED IN GOOD CONDITION.
BL0378
BL0378 STATION RECOVERY (1996)
BL0378
BL0378''RECOVERY NOTE BY US POWER SQUADRON 1996
BL0378''RECOVERED IN GOOD CONDITION."