Surrounded by no less than three witness posts and a power pole, no one could miss this once they're in the vicinity. It's about 70 feet west of the centerline of the highway and a bit south of the power pole. Below ground, it's a stainless steel rod in an aluminum valve box with a hinged cover. The designation is stamped on the edge of the cover, not the rod.
STATION DESCRIPTION
FBN - This is a Federal Base
Network Control Station.
DESIGNATION - P 513
PID - TP0881
STATE/COUNTY - WA/OKANOGAN
COUNTRY - US
USGS QUAD - TONASKET (1981)
MARKER: I = METAL ROD
SETTING: 49 = STAINLESS STEEL ROD W/O SLEEVE (10 FT.+)
STAMPING: P 513 1981
MARK LOGO: NGS
PROJECTION: FLUSH
DESCRIBED BY NATIONAL GEODETIC SURVEY 1981
THE MARK IS ABOVE LEVEL WITH THE HIGHWAY.
THE MARK IS A STAINLESS STEEL ROD SET UNDER A STANDARD NGS LOGO COVER THAT IS FLUSH WITH THE GROUND SURFACE. IT IS 20.3 M (66.6 FT) NORTHWEST OF THE CENTER OF US HIGHWAY 97, 2.4 M (7.9 FT) SOUTH OF A POWER LINE POLE NUMBERED L487 AND 0.3 M (1.0 FT) NORTHEAST OF A WITNESS POST.
From the NGS Datasheet