U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 PUBLICATION DATE: 10/29/1985 Station ID: 8453742 SUPERCEDED DATE: 04/21/2003 Name: WEST JAMESTOWN, CONANICUT ISLAND, DUTCHISLAND HARB RHODE ISLAND NOAA Chart: 13223 Latitude: 41° 29.8' N USGS Quad: NARRAGANSETT PIER Longitude: 71° 23.2' W To reach the tidal bench marks from Newport, Rhode Island proceed west across the Newport Bridge on State Road 138 onto Conanicut Island. Turn left (south) and travel 1 mile (1.6 km) to Narragansett Avenue. Turn right (west) onto Narragansett Avenue and travel 2 miles (3 km) until the road terminates at the wharf at Dutch Harbor. The bench marks are located in the vicinity of the parking area at the wharf. The tide gage and staff were located on the south side of the pier. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 3742 A 1977 MONUMENTATION: Survey Disk VM#: 2189 AGENCY: PID: SETTING CLASSIFICATION: Concrete Foundation The bench mark is set flush in the concrete slab at the entrance to the Dutch Harbor Marine Inc. Office, 42 feet (13 m) north of the centerline of Narragansett Avenue, 3.5 feet (1.1 m) north of the south end of the concrete slab, and 0.7 foot (0.2 m) west of the front wall of the Office. BENCH MARK STAMPING: 3742 B 1977 MONUMENTATION: Survey Disk VM#: 2190 AGENCY: PID: SETTING CLASSIFICATION: Concrete Seawall The bench mark is set flush in top of a small curb-like seawall on the north side of the parking area and west of the Dutch Harbor Marine Inc. Office, 75 feet (23 m) north of the centerline of Narragansett Avenue (extended) 37 feet (11 m) SE of the shoreline at the east end of the seawall (parking lot curb).
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 PUBLICATION DATE: 10/29/1985 Station ID: 8453742 SUPERCEDED DATE: 04/21/2003 Name: WEST JAMESTOWN, CONANICUT ISLAND, DUTCHISLAND HARB RHODE ISLAND NOAA Chart: 13223 Latitude: 41° 29.8' N USGS Quad: NARRAGANSETT PIER Longitude: 71° 23.2' W T I D A L B E N C H M A R K S BENCH MARK STAMPING: 3742 C 1977 MONUMENTATION: Survey Disk VM#: 2191 AGENCY: PID: SETTING CLASSIFICATION: Concrete Seawall The bench mark is set flush in top of a small curb-like seawall on the north side of the parking area, and west of the Dutch Harbor Marine Inc. Office, 61 feet (19 m) north of the centerline of Narragansett Avenue (extended), 33 feet (10 m) west of Bench Mark 3742 B 1977, and 24 feet (7 m) SE of the shoreline. BENCH MARK STAMPING: 3742 D 1977 MONUMENTATION: Survey Disk VM#: 2192 AGENCY: PID: SETTING CLASSIFICATION: Concrete Seawall The bench mark is set flush in top of a small curb-like seawall that is north of the parking area and west of the Dutch Harbor Marine Inc. Office, 44 feet (13 m) north of the centerline of Narragansett Avenue (extended) 41 feet (12 m) west of Bench Mark 3742 C 1977, in the vicinity where the shoreline meets the seawall. BENCH MARK STAMPING: 3742 E 1977 MONUMENTATION: Survey Disk VM#: 2193 AGENCY: PID: SETTING CLASSIFICATION: Concrete Seawall The bench mark is set flush in top of a small curb-like seawall north of the parking area and west of the Dutch Harbor Marine Inc. Office, 48 feet (15 m) west of Bench Mark 3742 D 1977, 24 feet (7 m) north of the centerline of Narragansett Avenue (extended), 7.5 feet (2 m) east of the end of the wooden pier, at the western end of the seawall.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 PUBLICATION DATE: 10/29/1985 Station ID: 8453742 SUPERCEDED DATE: 04/21/2003 Name: WEST JAMESTOWN, CONANICUT ISLAND, DUTCHISLAND HARB RHODE ISLAND NOAA Chart: 13223 Latitude: 41° 29.8' N USGS Quad: NARRAGANSETT PIER Longitude: 71° 23.2' W T I D A L B E N C H M A R K S BENCH MARK STAMPING: NO 10 1930 MONUMENTATION: Survey Disk VM#: 2194 AGENCY: PID#: LW0631 SETTING CLASSIFICATION: Stone Seawall The bench mark is set flush in top of a stone seawall south of Narragansett Avenue, 16.6 feet (5.1 m) south of the north end of the seawall, west of the shoreline.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 PUBLICATION DATE: 10/29/1985 Station ID: 8453742 SUPERCEDED DATE: 04/21/2003 Name: WEST JAMESTOWN, CONANICUT ISLAND, DUTCHISLAND HARB RHODE ISLAND NOAA Chart: 13223 Latitude: 41° 29.8' N USGS Quad: NARRAGANSETT PIER Longitude: 71° 23.2' W T I D A L D A T U M S Tidal datums at WEST JAMESTOWN, CONANICUT ISLAND, DUTCHISLAND HARB based on: LENGTH OF SERIES: 1 MONTH TIME PERIOD: SEPTEMBER 1977 TIDAL EPOCH: 1960-1978 CONTROL TIDE STATION: 8452660 NEWPORT Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET: HIGHEST OBSERVED WATER LEVEL (09/25/1977) = 5.19 MEAN HIGHER HIGH WATER MHHW = 3.90 MEAN HIGH WATER MHW = 3.66 MEAN TIDE LEVEL MTL = 1.90 MEAN LOW WATER MLW = 0.14 MEAN LOWER LOW WATER MLLW = 0.00 LOWEST OBSERVED WATER LEVEL (09/15/1977) = -0.81 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In FEET above: Stamping or Designation MLLW MHW 3742 A 1977 9.96 6.30 3742 B 1977 7.95 4.29 3742 C 1977 7.94 4.28 3742 D 1977 7.97 4.31 3742 E 1977 7.91 4.25 NO 10 1930 9.37 5.71
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 PUBLICATION DATE: 10/29/1985 Station ID: 8453742 SUPERCEDED DATE: 04/21/2003 Name: WEST JAMESTOWN, CONANICUT ISLAND, DUTCHISLAND HARB RHODE ISLAND NOAA Chart: 13223 Latitude: 41° 29.8' N USGS Quad: NARRAGANSETT PIER Longitude: 71° 23.2' W 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 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.