U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 6 Station ID: 9418686 PUBLICATION DATE: 06/23/2003 Name: HOOKTON SLOUGH,HUMBOLDT BAY CA NOAA Chart: 18622 Latitude: 40° 41.2' N ( 40.68670) USGS Quad: FIELDS LANDING Longitude: 124° 13.3' W (-124.22200) To reach the tidal bench marks from US Highway 101 take Loleta-Hookton Exit (about 16 km (10 mi) south of Eureka), along Salmon Creek Ranch access road north (on west side of US Highway 101) until it curves sharply left, continue straight through two ranch gates, left at third gate, right turn after 46 m (150 ft), follow levee SW until too narrow to be driven on, and then walk on north side of small slough until you reach another slough (Hookton Slough). The gage is located 91 m (300 ft) west SW of the point where you reach Hookton Slough. The tide gage and staff were located on a free standing pile in the slough. T I D A L B E N C H M A R K S
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 6 Station ID: 9418686 PUBLICATION DATE: 06/23/2003 Name: HOOKTON SLOUGH,HUMBOLDT BAY CA NOAA Chart: 18622 Latitude: 40° 41.2' N ( 40.68670) USGS Quad: FIELDS LANDING Longitude: 124° 13.3' W (-124.22200) T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: K 1087 1967 DESIGNATION: K 1087 MONUMENTATION: Bench Mark disk VM#: 8708 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: LV0255 SETTING CLASSIFICATION: Concrete headwall of culvert OPUS PID: LATITUDE: 40° 40.8' N ( 40.68000) LONGITUDE: 124° 12.1' W (-124.20200) The primary bench mark is a disk set in top at south end of west concrete headwall of culvert 68.80, 11.5 km (7.2 mi) north along US Highway 101 from Fortuna overpass at Fortuna, 0.97 km (0.6 mi) north of Hookton Road overpass, 9.14 m (30.0 ft) west of centerline of west lanes of highway, and 0.76 m (2.5 ft) below the highway. BENCH MARK STAMPING: 8686 A 1977 DESIGNATION: 941 8686 A MONUMENTATION: Tidal Station disk VM#: 8705 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID: LATITUDE: 40° 41.2' N ( 40.68670) LONGITUDE: 124° 13.3' W (-124.22200) The bench mark is a disk located 152 m (500 ft) SE of center of the slough, 12.19 m (40.0 ft) SE of junction of SE levee of slough and north drainage canal, 3.05 m (10.0 ft) NE of redwood witness post, and 1.07 m (3.5 ft) above grade (at the top of north levee drainage canal). The bench mark is crimped to the top of a copper clad rod and set 0.08 m (0.25 ft) below grade, inside a PVC pipe (at base of drainage canal levee).
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 6 Station ID: 9418686 PUBLICATION DATE: 06/23/2003 Name: HOOKTON SLOUGH,HUMBOLDT BAY CA NOAA Chart: 18622 Latitude: 40° 41.2' N ( 40.68670) USGS Quad: FIELDS LANDING Longitude: 124° 13.3' W (-124.22200) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 8686 C 1977 DESIGNATION: 941 8686 C MONUMENTATION: Tidal Station disk VM#: 8706 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID: LATITUDE: 40° 41.2' N ( 40.68670) LONGITUDE: 124° 13.3' W (-124.22200) The bench mark is a disk located 0.72 km (0.45 mi) NW of bench mark K 1078 1967, 46 m (150 ft) west of south bound lanes of US Highway 101, 9.75 m (32.0 ft) NE of center of McBride Ranch Road at turn in road, and 0.91 m (3.0 ft) SW of telephone pole on west side of highway. The bench mark is crimped to the top of a copper-clad rod, and set 0.08 m (0.25 ft) below grade, inside a PVC pipe. BENCH MARK STAMPING: 8686 D 1977 DESIGNATION: 941 8686 D MONUMENTATION: Tidal Station disk VM#: 8707 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID: LATITUDE: 40° 41.2' N ( 40.68670) LONGITUDE: 124° 13.3' W (-124.22200) The bench mark is a disk located 0.24 km (0.15 mi) west of US Highway 101 at the McBride Ranch equipment yard, 3.66 m (12.0 ft) south of center of Ranch Road, and 0.61 m (2.0 ft) west of NW corner of concrete building (dated 1923 above door). The bench mark is crimped to the top of a copper-clad rod, set 0.15 m (0.5 ft) below grade, inside a PVC pipe.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 6 Station ID: 9418686 PUBLICATION DATE: 06/23/2003 Name: HOOKTON SLOUGH,HUMBOLDT BAY CA NOAA Chart: 18622 Latitude: 40° 41.2' N ( 40.68670) USGS Quad: FIELDS LANDING Longitude: 124° 13.3' W (-124.22200) T I D A L B E N C H M A R K S BENCH MARK STAMPING: DESIGNATION: 941 8686 NO STAMPING 1 MONUMENTATION: Tidal Station disk VM#: 8709 AGENCY: Department of Interior (DOI) IDB PID#: SETTING CLASSIFICATION: Unspecified OPUS PID: LATITUDE: 40° 41.2' N ( 40.68670) LONGITUDE: 124° 13.3' W (-124.22200) The bench mark is a disk located at the gate to west stock yard, west of gate at end of McBride Ranch Road, 0.6 km (0.4 mi) WSW of west side of drainage ditch, 8.23 m (27.0 ft) east of concrete water trough, 4.57 m (15.0 ft) SW of gate past the west side of drainage ditch, 0.08 m (0.25 ft) north of steel witness post, and 0.15 m (0.5 ft) above grade.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 6 Station ID: 9418686 PUBLICATION DATE: 06/23/2003 Name: HOOKTON SLOUGH,HUMBOLDT BAY CA NOAA Chart: 18622 Latitude: 40° 41.2' N ( 40.68670) USGS Quad: FIELDS LANDING Longitude: 124° 13.3' W (-124.22200) T I D A L D A T U M S Tidal datums at HOOKTON SLOUGH,HUMBOLDT BAY based on: LENGTH OF SERIES: 1 Year TIME PERIOD: June 1978 - May 1979 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 9419750 CRESCENT CITY, PACIFIC OCEAN Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: MEAN HIGHER HIGH WATER MHHW = 2.114 MEAN HIGH WATER MHW = 1.893 MEAN SEA LEVEL MSL = 1.147 MEAN TIDE LEVEL MTL = 1.135 MEAN LOW WATER MLW = 0.376 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW K 1087 1967 1.886 -0.007 8686 A 1977 1.001 -0.892 8686 C 1977 1.921 0.028 8686 D 1977 1.665 -0.228 941 8686 NO STAMPING 1 1.172 -0.721
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 6 of 6 Station ID: 9418686 PUBLICATION DATE: 06/23/2003 Name: HOOKTON SLOUGH,HUMBOLDT BAY CA NOAA Chart: 18622 Latitude: 40° 41.2' N ( 40.68670) USGS Quad: FIELDS LANDING Longitude: 124° 13.3' W (-124.22200) D E F I N I T I O N S Mean Sea Level (MSL) is a tidal datum determined over a 19-year National Tidal Datum Epoch. It pertains to local mean sea level and should not be confused with the fixed datums of North American Vertical Datum of 1988 (NAVD88). NAVD88 is a fixed datum derived from a simultaneous, least squares, minimum constraint adjustment of Canadian/Mexican/United States leveling observations. Local mean sea level observed at Father Point/Rimouski, Canada was held fixed as the single initial constraint. NAVD88 replaces NGVD29 as the national standard geodetic reference for heights. Bench mark elevations relative to NAVD88 are available from NGS through the World Wide Web at National Geodetic Survey. NGVD29 is a fixed datum adopted as a national standard geodetic reference for heights but is now considered superseded. NGVD29 is sometimes referred to as Sea Level Datum of 1929 or as Mean Sea Level on some early issues of Geological Survey Topographic Quads. NGVD29 was originally derived from a general adjustment of the first-order leveling networks of the U.S. and Canada after holding mean sea level observed at 26 long term tide stations as fixed. Numerous local and wide-spread adjustments have been made since establishment in 1929. Bench mark elevations relative to NGVD29 are available from the National Geodetic Survey (NGS) data base via the World Wide Web at National Geodetic Survey. NAVD88 and NGVD29 are fixed geodetic datums whose elevation relationships to local MSL and other tidal datums may not be consistent from one location to another. The Vertical Mark Number (VM#) and PID# shown on the bench mark sheet are unique identifiers for bench marks in the tidal and geodetic databases, respectively. Each bench mark in either database has a single, unique VM# and/or PID# assigned. Where both VM# and PID# are indicated, both tidal and geodetic elevations are available for the bench mark listed. The NGS's Integrated Data Base (IDB PID) provides geodetic datum based on traditionally leveled and bluebooked ties to the National Spatial Reference System(NSRS) https://www.ngs.noaa.gov/datasheets/. The NGS Online Positioning User Service (OPUS PID) provides geodetic datum based on GPS position & tie it to the NSRS https://www.ngs.noaa.gov/OPUS/. The NAVD88 elevation is shown on the Elevations of Tidal Datums Table Referred to MLLW only when two or more of the bench marks listed have NAVD88 elevations. The NAVD88 elevation relationship shown in the table is derived from an average of several bench mark elevations relative to tide station datum. As a result of this averaging, NAVD88 bench mark elevations computed indirectly from the tidal datums elevation table may differ slightly from NAVD88 elevations listed for each bench mark in the NGS database.