U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 Station ID: 9418799 PUBLICATION DATE: 04/01/2004 Name: FRESHWATER SLOUGH, HUMBOLDT BAY CA NOAA Chart: 18622 Latitude: 40° 47.9' N ( 40.79830) USGS Quad: EUREKA Longitude: 124° 7.2' W (-124.12000) To reach the tidal bench marks from Eureka, proceed east along US Highway 101 to the Myrtle Avenue exit, then proceed SE along Myrtle Avenue for 2.01 km (1.25 mi), then turn left and proceed east on Park Street until it dead ends. The bench marks are located along Park Street. The tide gage and staff were on the wooden bridge over the slough. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 8799 A 1978 DESIGNATION: 941 8799 A TIDAL MONUMENTATION: Tidal Station disk VM#: 8728 AGENCY: National Ocean Survey (NOS) IDB PID#: LV0643 SETTING CLASSIFICATION: Galvanized steel rod OPUS PID: LATITUDE: 40° 47.7' N ( 40.79500) LONGITUDE: 124° 7.3' W (-124.12200) The primary bench mark is a disk located 62 m (203 ft) SW of SW corner of a wooden bridge, 4 m (13 ft) north of centerline of Park Street, and 1 m (2 ft) SW of corner of wooden fence. The bench mark is crimped to the the top of a galvanized steel rod driven 17.1 m (56 ft), and encased in concrete and a PVC pipe extending 15 cm (0.5 ft) above grade.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 Station ID: 9418799 PUBLICATION DATE: 04/01/2004 Name: FRESHWATER SLOUGH, HUMBOLDT BAY CA NOAA Chart: 18622 Latitude: 40° 47.9' N ( 40.79830) USGS Quad: EUREKA Longitude: 124° 7.2' W (-124.12000) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 8799 B 1978 DESIGNATION: 941 8799 B TIDAL MONUMENTATION: Tidal Station disk VM#: 8729 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Galvanized steel rod OPUS PID: LATITUDE: 40° 47.8' N ( 40.79670) LONGITUDE: 124° 7.1' W (-124.11800) The bench mark is a disk located 114 m (375 ft) west of east end of Park Street, 9 m (31 ft) SSW of SW corner of large garage, 2 m (8 ft) south of centerline of Park Street, and 1 m (3 ft) east of a witness post. The bench mark is crimped to the top of a galvanized steel rod driven 13.7 m (45 ft) and encased in concrete and a PVC pipe extending 0.21 m (0.7 ft) above grade. BENCH MARK STAMPING: 8799 C 1978 DESIGNATION: 941 8799 C TIDAL MONUMENTATION: Tidal Station disk VM#: 8730 AGENCY: National Ocean Survey (NOS) IDB PID#: SETTING CLASSIFICATION: Galvanized steel rod OPUS PID: LATITUDE: 40° 47.8' N ( 40.79670) LONGITUDE: 124° 7.1' W (-124.11800) The bench mark is a disk located 198 m (650 ft) east along Park Street from center of intersection of Park and Quakes Streets, 11 m (36 ft) east of centerline of dirt driveway, 3.81 m (12.5 ft) SSW of centerline of Park Street, and 1 m (2 ft) ESE of witness post. The bench mark is crimped to the top of a galvanized steel rod driven 9.5 m (31 ft) and encased in concrete and a PVC pipe extending 12 cm (0.4 ft) above grade.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 Station ID: 9418799 PUBLICATION DATE: 04/01/2004 Name: FRESHWATER SLOUGH, HUMBOLDT BAY CA NOAA Chart: 18622 Latitude: 40° 47.9' N ( 40.79830) USGS Quad: EUREKA Longitude: 124° 7.2' W (-124.12000) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 8799 E 1978 DESIGNATION: 941 8799 E TIDAL MONUMENTATION: Tidal Station disk VM#: 8731 AGENCY: National Ocean Survey (NOS) IDB PID#: LV0642 SETTING CLASSIFICATION: Sidewalk OPUS PID#: LV0642 LATITUDE: 40° 47.7' N ( 40.79500) LONGITUDE: 124° 7.6' W (-124.12700) The bench mark is a disk set flush in the NE corner of sidewalk at the SW corner of the T intersection of Park and Quaker Streets, 11 m (37 ft) SW of center of intersection, and 3 m (11 ft) east of the fire hydrant.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 Station ID: 9418799 PUBLICATION DATE: 04/01/2004 Name: FRESHWATER SLOUGH, HUMBOLDT BAY CA NOAA Chart: 18622 Latitude: 40° 47.9' N ( 40.79830) USGS Quad: EUREKA Longitude: 124° 7.2' W (-124.12000) T I D A L D A T U M S Tidal datums at FRESHWATER SLOUGH, HUMBOLDT BAY based on: LENGTH OF SERIES: 8 MONTHS TIME PERIOD: May 1978 - December 1978 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 = 2.162 MEAN HIGH WATER MHW = 1.943 MEAN TIDE LEVEL MTL = 1.137 MEAN SEA LEVEL MSL = 1.111 MEAN LOW WATER MLW = 0.332 North American Vertical Datum NAVD88 = 0.138 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW 8799 A 1978 2.913 0.970 8799 B 1978 2.371 0.428 8799 C 1978 5.365 3.422 8799 E 1978 20.639 18.696
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 Station ID: 9418799 PUBLICATION DATE: 04/01/2004 Name: FRESHWATER SLOUGH, HUMBOLDT BAY CA NOAA Chart: 18622 Latitude: 40° 47.9' N ( 40.79830) USGS Quad: EUREKA Longitude: 124° 7.2' W (-124.12000) 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.