Though in the spring it could be covered with sand and in the winter with snow, this Benchmark is easy to find if one can find a 650 foot long bridge. The benchmark is in the east curb at the north end of the bridge, about 2 feet from the north end and about a foot in from the curb edge.
STATION DESCRIPTION
DESIGNATION - L 513
PID - TP0878
STATE/COUNTY- WA/OKANOGAN
COUNTRY - US
USGS QUAD - TONASKET (1981)
MARKER: DB = BENCH MARK DISK
SETTING: 31 = SET IN A PAVEMENT SUCH AS A CURB
SP_SET: BRIDGE CURB
STAMPING: L 513 1981
MARK LOGO: NGS
DESCRIBED BY NATIONAL GEODETIC SURVEY 1981
19.1 KM (11.85 MI) NORT FROM RIVERSIDE.
ALONG US HIGHWAY 97, IN TOP OF THE NORTHEAST END OF THE SOUTHEAST CURB OF A CONCRETE BRIDGE OVER
THE OKANOGAN RIVER AND THE BURLINGTON NORTHERN RAILROAD, 7.0 KM (4.35 MI) SOUTH OF TONASKET, 0.25 METER (0.8 FT) SOUTHEAST OF THE NORTHWEST EDGE OF THE CURB, 0.5 METER (1.5 FT) SOUTHWEST OF THE NORTHEAST EDGE OF THE CURB.
THE MARK IS 0.15 M ABOVE THE HIGHWAY.
From the NGS Datasheet