U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 8 Station ID: 9448558 PUBLICATION DATE: 07/15/2004 Name: LA CONNER, SWINOMISH SLOUGH WA NOAA Chart: 18427 Latitude: 48° 23.5' N ( 48.39170) USGS Quad: LA CONNER Longitude: 122° 29.8' W (-122.49700) To reach the tidal bench marks from Mount Vernon, proceed west on State Highway 536 for 10 km (6 mi) to Best Road, then turn left and proceed south on Best Road for 6 km (4 mi), then turn right and proceed west on Chillberg Road (which becomes Morris Street) for 3 km (2 mi) to the end of the street in the town of La Conner. The bench marks are located at the library, post office, and Conner Park. The tide gage and staff were located at the wharf beside Channel Boat House. 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 8 Station ID: 9448558 PUBLICATION DATE: 07/15/2004 Name: LA CONNER, SWINOMISH SLOUGH WA NOAA Chart: 18427 Latitude: 48° 23.5' N ( 48.39170) USGS Quad: LA CONNER Longitude: 122° 29.8' W (-122.49700) T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 3 1935 DESIGNATION: TIDAL 3 MONUMENTATION: Bench Mark disk VM#: 9253 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: TR0236 SETTING CLASSIFICATION: Rock outcrop OPUS PID: LATITUDE: 48° 23.6' N ( 48.39330) LONGITUDE: 122° 29.8' W (-122.49700) The primary bench mark is a disk set in the top of the lower of two natural steps in a large rock outcrop on the south side of Washington Street between First and Second Streets, 41 m (135 ft) east of the intersection of First and Washington Streets, 29 m (94 ft) east of the SE curb of First Street, 1.37 m (4.5 ft) south of a path leading uphill from First Street, and 5 m (15 ft) above the level of First Street.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 8 Station ID: 9448558 PUBLICATION DATE: 07/15/2004 Name: LA CONNER, SWINOMISH SLOUGH WA NOAA Chart: 18427 Latitude: 48° 23.5' N ( 48.39170) USGS Quad: LA CONNER Longitude: 122° 29.8' W (-122.49700) T I D A L B E N C H M A R K S BENCH MARK STAMPING: TIDAL 4 RESET 1967 DESIGNATION: TIDAL 4 RESET MONUMENTATION: Tidal Station disk VM#: 9255 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: SETTING CLASSIFICATION: Concrete foundation OPUS PID: LATITUDE: 48° 23.5' N ( 48.39170) LONGITUDE: 122° 29.8' W (-122.49700) The bench mark is a disk set in the SE corner of a concrete foundation for four storage tanks of the Chevron Oil Company, 61 m (200 ft) NE of the centerline of the intersection of Third and Morris Streets, 27 m (90 ft) south of the centerline of Crater Street, 16.61 m (54.5 ft) NW of the NW corner of Chevron Service Station, 5.64 m (18.5 ft) north of the SE corner of a low concrete wall surrounding a group of oil storage tanks, and 0.46 m (1.5 ft) east of the east concrete wall.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 8 Station ID: 9448558 PUBLICATION DATE: 07/15/2004 Name: LA CONNER, SWINOMISH SLOUGH WA NOAA Chart: 18427 Latitude: 48° 23.5' N ( 48.39170) USGS Quad: LA CONNER Longitude: 122° 29.8' W (-122.49700) T I D A L B E N C H M A R K S BENCH MARK STAMPING: TIDAL 6 1972 DESIGNATION: TIDAL 6 MONUMENTATION: Tidal Station disk VM#: 9256 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: SETTING CLASSIFICATION: Rock outcrop OPUS PID: LATITUDE: 48° 23.5' N ( 48.39170) LONGITUDE: 122° 29.8' W (-122.49700) The bench mark is a disk set in a rock outcrop near the library between First and Second Streets, 2.10 m (6.9 ft) SE of the NE corner of the library, and 1.07 m (3.5 ft) above the ground.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 8 Station ID: 9448558 PUBLICATION DATE: 07/15/2004 Name: LA CONNER, SWINOMISH SLOUGH WA NOAA Chart: 18427 Latitude: 48° 23.5' N ( 48.39170) USGS Quad: LA CONNER Longitude: 122° 29.8' W (-122.49700) T I D A L B E N C H M A R K S BENCH MARK STAMPING: TIDAL 7 1972 DESIGNATION: TIDAL 7 MONUMENTATION: Tidal Station disk VM#: 9257 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: SETTING CLASSIFICATION: Concrete loading ramp OPUS PID: LATITUDE: 48° 23.5' N ( 48.39170) LONGITUDE: 122° 29.8' W (-122.49700) The bench mark is a disk set in the NE corner of the concrete loading ramp of the U.S. Post Office on First Street, 34 m (113 ft) NNW of the intersection of Washington and Second Streets, 0.40 m (1.3 ft) west of the NE corner of the building, and 0.76 m (2.5 ft) above the parking lot.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 6 of 8 Station ID: 9448558 PUBLICATION DATE: 07/15/2004 Name: LA CONNER, SWINOMISH SLOUGH WA NOAA Chart: 18427 Latitude: 48° 23.5' N ( 48.39170) USGS Quad: LA CONNER Longitude: 122° 29.8' W (-122.49700) T I D A L B E N C H M A R K S BENCH MARK STAMPING: TIDAL 8 1972 DESIGNATION: TIDAL 8 MONUMENTATION: Tidal Station disk VM#: 9258 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: SETTING CLASSIFICATION: Bedrock OPUS PID: LATITUDE: 48° 23.5' N ( 48.39170) LONGITUDE: 122° 29.8' W (-122.49700) The bench mark is a disk set in bedrock on the north edge of Conner Park, 29 m (95 ft) WSW of the intersection of Washington and Second Streets, 10 m (34 ft) SE of the centerline of Washington Street, 5 m (18 ft) north of a trail through the park, and 1 m (3 ft) below the trail.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 7 of 8 Station ID: 9448558 PUBLICATION DATE: 07/15/2004 Name: LA CONNER, SWINOMISH SLOUGH WA NOAA Chart: 18427 Latitude: 48° 23.5' N ( 48.39170) USGS Quad: LA CONNER Longitude: 122° 29.8' W (-122.49700) T I D A L D A T U M S Tidal datums at LA CONNER, SWINOMISH SLOUGH based on: LENGTH OF SERIES: 2 MONTHS TIME PERIOD: December 1972 - January 1973 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 9447130 SEATTLE, PUGET SOUND Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: MEAN HIGHER HIGH WATER MHHW = 3.154 MEAN HIGH WATER MHW = 2.874 MEAN TIDE LEVEL MTL = 1.848 MEAN SEA LEVEL MSL = 1.817 MEAN LOW WATER MLW = 0.822 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW 3 1935 7.638 4.764 TIDAL 4 RESET 1967 3.171 0.297 TIDAL 6 1972 5.250 2.376 TIDAL 7 1972 4.030 1.156 TIDAL 8 1972 7.146 4.272
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 8 of 8 Station ID: 9448558 PUBLICATION DATE: 07/15/2004 Name: LA CONNER, SWINOMISH SLOUGH WA NOAA Chart: 18427 Latitude: 48° 23.5' N ( 48.39170) USGS Quad: LA CONNER Longitude: 122° 29.8' W (-122.49700) 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.