WATER LEVEL STATION 

SPECIFICATIONS AND DELIVERABLES 

FOR 

 SHORELINE MAPPING PROJECTS 

May 2009 

Center for Operational Oceanographic Products and Services 

National Ocean Service 

National Oceanic and Atmospheric Administration
 

Table of Contents 

1. Tides and Water Levels Requirements ................................................................................ 1

1.1 General Project Requirements and Scope ........................................................................ 1 

1.1.1 Scope ......................................................................................................................... 1 

1.1.2 Objectives ................................................................................................................. 1 

1.1.3 Planning and Tidal Zoning........................................................................................ 2 

1.1.4 NOS Control Stations and Data Quality Monitoring ................................................ 2 

1.1.4.1 National Water Level Observation Network (NWLON) .................................. 2 

1.1.4.2 Data Quality Monitoring ................................................................................... 2 

1.1.5 General Data and Reference Datum Requirements .................................................. 3 

1.1.6 Error Budget Considerations ..................................................................................... 3 

1.2 Data Collection and Field Work ....................................................................................... 5 

1.2.1 Water Level Station Requirements ........................................................................... 5 

1.2.2 Water Level Measurement Systems and Data Transmissions .................................. 5 

1.2.2.1 Water Level Sensor and Data Collection Platform ........................................... 5 

1.2.2.2 Data Transmissions............................................................................................ 7 

1.2.3 Station Installation, Operation and Removal ............................................................ 8 

1.2.3.1 Station Installation ............................................................................................. 8 

1.2.3.2 Operation and Maintenance ............................................................................... 8 

1.2.3.3 Removal ............................................................................................................. 9

1.2.4 Tide Staffs, Staff Observations, and Bubbler/Pressure Sensor Orifice .................... 9 

1.2.4.1 Staff ................................................................................................................... 9 

1.2.4.2 Staff Observations ........................................................................................... 10 

1.2.5 Bench Marks and Leveling ..................................................................................... 14 

1.2.5.1 Bench Marks .................................................................................................... 14 

1.2.5.2 Number and Type of Bench Marks ................................................................. 14 

1.2.5.3 Leveling ........................................................................................................... 14

1.2.5.4 Leveling Frequency ......................................................................................... 15 

1.2.5.5 Stability ............................................................................................................ 15 

1.2.6 Water Level Station Documentation ....................................................................... 15 

1.2.7 Additional Field Requirements ............................................................................... 16 

1.3 Data Processing and Reduction ...................................................................................... 16 

1.3.1 Data Quality Control ............................................................................................... 16 

1.3.2 Data Processing and Tabulation of the Tide ........................................................... 17 

1.3.3 Computation of Monthly Means ............................................................................. 17 

1.3.4 Data Editing and Gap Filling Specifications .......................................................... 18 

1.4 Computation of Tidal Datums and Water Level Datums ............................................... 22 

1.4.1 National Tidal Datum Epoch .................................................................................. 22 

1.4.2 Computational Procedures ...................................................................................... 22 

1.4.3 Tidal Datum Recovery ............................................................................................ 22 

1.4.4 Datum Quality Control ........................................................................................... 23 
 

1.5 Data Submission Requirements ..................................................................................... 38 

1.5.1 Station Documentation............................................................................................ 38 

1.5.2 Water Level Data .................................................................................................... 42 

1.5.2.1 Acoustic Sensor Data (XXX.ACO format) ..................................................... 43 

1.5.2.2 Pressure Sensor or Generic Data (XXX.BWL format) ................................... 43 

1.5.2.3 Tabulations and Tidal Datums ......................................................................... 44 

1.5.2.4 Hourly Height data Format .............................................................................. 44 

1.5.2.5 High/Low Data Format .................................................................................... 44 

1.5.2.6 Monthly Mean Data Format ............................................................................ 45 

1.5.2.7 Station Datum Data Format ............................................................................. 46 

1.5.3 Submission and Deliverables – Documentation and Time lines ............................ 48 

1.6 Guidelines and References ............................................................................................. 50 
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1. Tides and Water Levels Requirements 

1.1 General Project Requirements and Scope 

1.1.1 Scope 

The requirements and specifications contained in this section cover the water level and tidal 

datum requirements for the operational support of the remote sensing surveys conducted as part 

of the NOAA National Geodetic Survey (NGS) Coastal Mapping Program (CMP). The scope of 

this support is comprised of the following functional areas: 

1. Tide and water level requirements planning 

2. Tidal zoning development 

3. National Water Level Observation Network (NWLON) control water level station 

operation, monitoring, and maintenance 

4. Subordinate water level station installation, operation, monitoring, maintenance, and 

removal 

5. Data quality control, processing, and tabulation 

6. Tidal datum computation and tidal datum recovery 

7. Quality control check and data validation of contractor submitted data to CO-OPS 

For NGS in-house CMP surveys, personnel from the NOAA’s National Ocean Service (NOS) 

Center for Operational Oceanographic Products and Services (CO-OPS) are responsible for 

functional areas 1, 2, 3, 5, and 6. CO-OPS, NGS, or CO-OPS or NGS selected contractors may 

install, maintain, and remove the gauges, but CO-OPS will be responsible for monitoring and 

operation of the water level gauges. 

For NGS contract CMP surveys, CO-OPS personnel are responsible for functional areas 1, 2, 3 

and 7. NGS contract personnel shall be responsible for functional areas 4 through 6 above. COOPS will be responsible for operating, maintaining, and processing data from the National Water 

Level Observation Network (NWLON) control stations. 

1.1.2 Objectives 

The work performed according to the requirements and specifications of this document is 

required for shoreline mapping and aerial photogrammetry products and services. The first 

objective is to provide the tidal predictions and tidal zoning so that flight windows can be 

determined. The second objective is to ensure remotely sensed data can be collected at the 

proper stages of the tide (Mean High Water (MHW) plus or minus tolerances, and Mean Lower 

Low Water (MLLW) plus or minus tolerances) as per the NGS CMP Statement of Work (SOW) 

specifications based upon the tidal zoning. A third objective is to establish and/or recover tidal 

datums, connect to geodetic datums where possible, and connect to NSRS and ellipsoid via GPS 

observations on a tidal or geodetic bench mark. A fourth objective is to provide new information 

or updated information that can be used to update tide prediction tables, produce or update 

shoreline mapping products, support coastal resource management, and support marine 

engineering applications. A fifth objective is to verify the tidal data so that the imagery can be 
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checked to ensure the tolerances were met. The products derived support the NOAA strategic 

goals of Commerce and Transportation, Weather and Water, and Ecosystem and Climate. 

1.1.3 Planning and Tidal Zoning 

CO-OPS is responsible for all planning of tide and water level requirements for NOS Coastal Mapping 

Program surveys. CO-OPS will analyze historical data and tidal characteristics for each project area, 

specify control water level stations, specify subordinate water level station locations to be installed, and 

provide the tidal zoning to be used during shoreline mapping surveys. CO-OPS will provide 6-minute 

interval tide predictions relative to MHW and MLLW for appropriate NOS control stations prior to each 

survey and will also provide historical published bench mark information available for all historical tide 

stations specified for reoccupation. The definitions of MLLW and MHW are located at 

http://tidesandcurrents.noaa.gov/publications/glossary2.pdf

1.1.4 NOS Control Stations and Data Quality Monitoring 

1.1.4.1 National Water Level Observation Network (NWLON) 

CO-OPS manages the NWLON of approximately 205 (as of October 2008) continuously 

operating water level observation stations in the U.S. coastal zone, including the Great Lakes. 

As most of these stations are equipped with satellite radios, near real-time (within about 30 

minutes of collection) preliminary data are made available to all users through the CO-OPS Web 

page at http://tidesandcurrents.noaa.gov. Verified products, such as edited 6-minute data, hourly 

heights, high and low waters, and monthly means are made available over the Web within one to 

four weeks after data collection for NWLON stations. Accepted tidal datums relative to the 

National Tidal Datum Epoch (NTDE) are also available on the web. NWLON data and accepted 

tidal datums are used to provide tide reducers, control for tidal zoning, and for control for datum 

determination at subordinate (short-term) stations. Preliminary and verified data are made 

available over the Web relative to MLLW, or MHW datum, station datum, or special water level 

datum (such as Columbia River datum) as a user option in the interface. 

1.1.4.2 Data Quality Monitoring 

CO-OPS has an in-place Continuous Operational Real-Time Monitoring System (CORMS) that 

provides quality control and system monitoring functions on a 24 hour/day, 7 days/week, all year 

around basis for CO-OPS monitored gauges. CORMS will monitor the status and performance 

of all in-house water level gauges equipped with satellite radios using the NOS satellite message 

format and that are installed by either CO-OPS, or CO-OPS contractors for NOS in-house l 

shoreline mapping projects only, and once these gauges are listed on the Hydro Hot List (HHL) 

by CO-OPS. CORMS monitors all NOS water level systems, including all NWLON 

stations. HHL is a web based list where real time preliminary water level data for selected 

stations is made available to users. HHL lists water level gauges that are configured in CO-OPS 

Database Management System (DMS). 

For shoreline mapping contract surveys, the contractor is responsible for all data monitoring, 

repairs, and ensuring the proper gauge operation of the subordinate stations. 
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1.1.5 General Data and Reference Datum Requirements 

The present NOAA Nautical Chart Reference Datum for soundings for tidal waters is MLLW 

(see: Tide and Current Glossary, at http://tidesandcurrents.noaa.gov/publications/glossary2.pdf) 

based on the latest NOAA National Tidal Datum Epoch (NTDE) of 1983-2001. The present 

NOAA shoreline reference datum is MHW. All tidal datum computations and water level 

reductions for shoreline surveys shall be referenced to these datums. In non-tidal areas, 

including the Great Lakes, special low water datums have been defined for specific areas and are 

used as chart datum in these locations. In some cases where historical sites are re-occupied, site 

datum shall be zeroed to a pre-established MLLW datum held on a bench mark. In that case, data 

can be acquired relative to MLLW for immediate application during the survey. 

For non-tidal areas such as the Great Lakes areas, a unique Low Water Datum (LWD) for each 

lake relative to International Great Lakes Datum of 1985 (IGLD 85) is the reference datum. In 

other non-tidal coastal areas, LWD is determined by subtracting 0.5 ft from Mean Water Level 

(MWL) (equivalent to Mean Sea Level (MSL)) observed at the water level stations. 

1.1.6 Error Budget Considerations 

The accuracy of measuring shoreline can vary significantly depending upon the slope the 

coastline. The error for estimating the shoreline (horizontal location of MHW or MLLW 

intersects the shore) is reduced for steep slope of coastline, whereas for areas of flat coastline the 

error for estimating the shoreline is increased. 

The following table provides potential horizontal displacements of boundary positions resulting 

from errors in vertical datum determinations 

Error in datum (in 

meters and feet) 

Horizontal Displacement of Boundary for Beach Slope of Angle 

with Horizontal as listed below (in meters & feet) 

 30 degrees 10 degrees 1 degree 

0.61 m ( 2.0 ft) 1.05 m (3.46 ft) 3.46 m (11.34 ft) 34.92 m (114.58 ft) 

0.91 m (1.5 ft) 0.79 m (2.60 ft) 2.59 m (8.51 ft) 16.19 m (85.94 ft) 

0.30 m (1.0 ft) 0.52 m(1.73 ft) 1.73 m (5.67 ft) 17.46 m (57.29 ft) 

0.15 m (0.5 ft) 0.26 m (0.87 ft) 0.86 m (2.84 ft) 8.72 m (28.64 ft) 

0.03 m (0.1 ft) 0.05 m (0.17 ft) 0.17 m (0.57 ft) 1.74 m (5.73 ft) 

What the table shows is that the horizontal displacement is the largest for a flat beach slope. The 

errors demonstrated in this table in turn drive the operational error budgets described in the next 

paragraph. 

According to NGS Scope of Work (Attachment J – Tide Coordination Requirements), the 

imagery shall be obtained within a tolerance as specified of MHW and MLLW to determine the 

shoreline. When the mean range of the tide station is 5 feet (1.5 m) or less the tolerance is +/- 

0.3 feet (0.1 m), and when the mean range of the tide station is greater than 5 feet (1.5 m), the 

tolerance is +/- 10% of the mean range. So the MHW +/- tolerance creates time windows during 
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which the imagery needs to be obtained for high water shoreline, and MLLW +/- tolerance 

creates time windows during which the imagery needs to be obtained for the low water shoreline. 

In order to meet these error and tolerance targets, the allowable contribution of the error for tides 

and water levels is estimated between 0.20 m and 0.45 m (at the 95% confidence level) 

depending on the complexity of the tides. These numbers were developed from NOS internal 

study for hydrographic surveys and are applicable whenever tidal zoning is used for shoreline 

mapping projects. 

The total error of the tides and water levels can be considered to have component errors of: 

1. The measurement error of the gauge/sensor and processing error to refer the 

measurements to station datum. Gauges/sensors need to be calibrated, and sensor design 

and data sampling need to include strategies to reduce measurement errors due to waves, 

currents, temperature, and density effects. The measurements need to be properly 

referenced to the bench marks and tide staffs, as appropriate and monitored for vertical 

stability. The measurement error, including the dynamic effects, should not exceed 0.10 

m at the 95% confidence level. The processing error also includes interpolation error of 

the water level at the exact time of the imagery. An estimate for a typical processing error 

is 0.10 m at the 95% confidence level. 

2. The error in computation of tidal datums for the adjustment to an equivalent 19-year 

National Tidal Datum Epoch (NTDE) periods for short term stations. The shorter the time 

series, the less accurate the datum, i.e. bigger the error. An inappropriate control station 

also decreases accuracy. The NTDE does not apply in the Great Lakes, however the 

accuracy of datum based on shorter time series is analogous. The estimated error of an 

adjusted tidal datum based on one month of data is 0.08 m for the east and west coasts 

and 0.11 m for the Gulf coast (at the 95% confidence level). 

3. The error in application of tidal zoning. Tidal zoning is the extrapolation and/or 

interpolation of tidal characteristics from a known shore point(s) to a desired survey area 

using time differences and range ratios. The greater the extrapolation/interpolation, the 

greater the uncertainty and error. Estimates for typical errors associated with tidal zoning 

are 0.20 m at the 95% confidence level. However, errors for this component can easily 

exceed 0.20 m if tidal characteristics are very complex, or not well-defined, and if there 

are pronounced differential effects of meteorology on the water levels across the survey 

area. 

Project planning by NOS attempts to minimize and balance these potential sources of errors 

through the use and specification of accurate and reliable water level gauges, optimization of the 

mix of zoning required, the number and locations of water level gauges required, and the length 

of observations required within practical limits of the survey area and survey duration. The 

practical limits depend upon the tidal characteristics of the area and suitability of the coastline 

for the installation and operation of appropriate water level stations. 
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1.2 Data Collection and Field Work 

Continuous and valid water level data series are required. Accurate datums cannot be computed 

for a month of data with a break in the water level measurement series in excess of three days. 

Even breaks of significantly less than three days duration will not allow for interpolation during 

times when strong meteorological conditions are present and in areas with little periodic tidal 

influence. Any break in the water level measurement series affects the accuracy of datum 

computations. At each measurement site where the water level measurement data cannot be 

transmitted or monitored during the survey operations, an independent backup sensor or a 

complete redundant water level collection system shall be installed and operated during the 

project. 

1.2.1 Water Level Station Requirements 

Data from NWLON stations will be provided to support the both in-house and contract shoreline 

mapping survey operations. Tidal Predictions are also made available for NWLON stations on 

CO-OPS web page. Tidal predictions for historic subordinate stations can also be made 

available if CO-OPS has the historical tide station information. 

The acquisition of water level data from subordinate locations may be required for shoreline 

mapping surveys and if so shall be specified by NOS in each individual set of Project 

Instructions. These stations shall be used to provide 6-minute time series data, tidal datum 

references and tidal zoning which all factor into the production of final tide reducers for specific 

survey areas. Station locations and requirements may be modified after station reconnaissance or 

as survey operations progress. Any changes shall be made only after consultation between the 

CO-OPS and Chief, Remote Sensing Division (RSD) (and COTR if contract survey) as 

relocating the required stations to new locations may require assignment of new seven-digit 

station identifier numbers, and new/historical station and bench mark information.. CO-OPS 

may not have adequate information to correctly determine the tides at new tide gauge location 

and that may affect the availability of tide predictions. 

The duration of continuous water level data acquisition shall be a 30-day minimum. Water level 

data acquisition shall be from at least 4 hours before the beginning of the shoreline mapping 

survey operations to 4 hours after the ending of shoreline mapping survey operations, and/or 

shoreline verification in the applicable areas. 

1.2.2 Water Level Measurement Systems and Data Transmissions 

1.2.2.1 Water Level Sensor and Data Collection Platform 

The water level sensor shall be a self-calibrating air acoustic, pressure (vented), or other suitable 

type that is approved by CO-OPS. The sensor measurement range shall be greater than the 

expected range of water level. Gauge/sensor systems shall be calibrated prior to deployment, 

and the calibration shall be checked after removal from operations. The calibration standard’s 

accuracy must be traceable to National Institute of Standards and Technology (NIST). The 

required water level sensor resolution is a function of the tidal range of the area in which 
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shoreline mapping surveys are planned. For tidal range less than or equal to 5 m, the required 

water level sensor resolution shall be 1 mm or less; for tidal range between 5 m and 10 m, the 

required water level sensor resolution shall be 3 mm or less; and for tidal range greater than 10 

m, the required water level sensor resolution shall be 5 mm or less. 

The Data Collection Platform (DCP) shall acquire and store water level measurements every 6- 

minutes. The water level measurements shall consist of an average of at least three minutes of 

discrete water level samples with the period of the average centered about the six minute mark 

(i.e. :00, :06, :12, etc.). In addition to the average measurement, the standard deviation of the 

discrete water level samples which comprise the 6-minute measurements shall be computed and 

stored. The 6-minute centered average water level data is required for compatibility with the 

NWLON stations, and the standard deviation provides valuable data quality information 

regarding each measurement. The clock accuracy of a satellite radio system shall be within 1 

second per month so that channel “stepping” does not occur. Non-satellite radio systems shall 

have a clock accuracy of within one minute per month. Known error sources for each sensor 

shall be handled appropriately through ancillary measurements and/or correction algorithms. 

Examples of such errors are water density variations for pressure gauges, sound path air 

temperature differences for acoustic systems, and high frequency wave action and high velocity 

currents for all sensor types. 

The NOS is currently using the Aquatrak® self-calibrating air acoustic sensors at the majority of 

the NWLON stations. (For further information refer to Next Generation Water level 

Measurement System (NGWLMS) Site Design, Preparation, and Installation Manual, 

NOAA/NOS, January 1991, which is available at CO-OPS web page at the following url: 

(http://tidesandcurrents.noaa.gov/publications/NextGenerationWaterLevelMeasurementSystemM

ANUAL.pdf) and User’s Guide for 8200 Acoustic Gauges, NOAA/NOS, Updated August 1998 

which is available at http://tidesandcurrents.noaa.gov/publications/hy8200aco_manual.pdf). 

At stations where the acoustic sensor can not be used due to freezing or the lack of a suitable 

structure, either a ParoScientific intelligent pressure (vented) sensor incorporated into a gas 

purge system, or a well/float with absolute shaft angle encoder (Great Lakes Stations) are used 

by NOS for water level measurements. (For further information refer to User’s Guide for 8200 

Bubbler Gauges, NOAA/NOS, Updated February 1998 which is available at CO-OPS web page 

at the following url: http://tidesandcurrents.noaa.gov/publications/hy8200bub_manual.pdf ). 

Also refer to User’s Guide for 8210 Bubbler Water Level Gauge for Hydrographic Surveying 

Applications (Installation and Operation) February 2001 which is available at CO-OPS web page 

at the following URL: http://tidesandcurrents.noaa.gov/publications/8210_guide.pdf 

When using the vented pressure sensor, a series of gauge/staff comparisons through a significant 

portion of a tidal cycle (minimum 3 hours) is required, see Section 1.2.4.2 Staff Observations for 

further details. Along with the averaging procedure described above which works as a digital 

filter, NOS uses a combination protective well/parallel plate assembly on the acoustic sensor and 

a parallel plate assembly (with 2" orifice chamber) on the bubbler orifice sensor to minimize 

systematic measurement errors due to wave effects and current effects, as shown in Figure 1.1. 

When pressure sensors are used to collect the water level data, orifice should be mounted on 

vertical surface such as piling of a wharf so that precise elevation of orifice below a staff stop 
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can be measured with a steel tape, and the elevation of the staff stop can be measured via 

differential leveling to the nearest benchmark and with the primary bench mark. If the orifice is 

mounted vertically and its elevation can be determined precisely with reference to the primary 

bench mark, then staff to gauge readings may not be necessary, and the requirement for staff to 

gauge readings may be waived. If the orifice can not be mounted to a vertical surface i.e. if the 

elevation of the orifice can not be determined precisely with the primary bench mark, then staffs 

to gauge readings are required to relate the water level datums to the bench marks. Refer to 

Section 1.2.4.1 for further discussion. 

1.2.2.2 Data Transmissions 

The data transmissions requirements are applicable where CO-OPS is monitoring the gauges as 

described in Section 1.1.4.2 Data Quality Monitoring above. The ability to monitor water level 

measurement system performance for near real-time quality assurance is essential to properly 

support shoreline mapping operations. Therefore, it is required that, where access to the satellite 

is available, the measurement system shall be equipped with a GOES transmitter to telemeter the 

data to NOS every three hours, hourly, or every 6 minutes. The data transmissions must use a 

message format identical to the format as currently implemented in NOS’ Next Generation 

Water Level Measurement Systems (NGWLMS). This is required to assure direct compatibility 

with the NOS Data Management System (DMS). This data format is detailed in the reference 

document “NGWLMS GOES MESSAGE FORMATTING” (refer to Section 1.6 for Guidelines 

and References) and is available at CO-OPS web page at the following URL: 

http://tidesandcurrents.noaa.gov/publications/newgoes_format.pdf. Once the station and gauge 

information is configured in DMS and station listed on the Hydro Hot List (HHL), (which is 

available at CO-OPS web page at the following url: 

http://tidesandcurrents.noaa.gov/hydro.shtml) the NOS Continuous Operational Real-Time 

System (CORMS) will monitor all water level measurement system GOES transmissions to 

assure they are operating properly, provided that the GOES data transmitted is compatible with 

NOS format and CO-OPS is responsible for the operation of the gauge. Data that is not 

transmitted by GOES, or data transmitted but not in NOS compatible GOES format, or is 

submitted to CO-OPS on electronic formats currently used such as, CD-ROM, DVD-ROM or 

such other digital media, must also conform to the format specified in the above document so 

that data can be loaded properly into DMS software. Refer to Section 1.5.2 for further details 

about the water level data format specifications. 

Close coordination is required between NGS personnel, installer, and the Operational 

Engineering Team (OET) of the Engineering Division (ED) of CO-OPS for all NOAA in-house 

shoreline mapping survey projects that have satellite transmission capability for water level 

installations. NOS will assist in acquiring assigned platform ID’s, time slots, etc. for NGS inhouse shoreline mapping projects. At least three business days prior to the installation of the tide 

gauge in the field, information about the station number, station name, latitude, longitude, 

platform-ID, transmit time, channel, and serial numbers of sensors, and DCP shall be faxed 

(telephone 301-713-4465), phoned (telephone 301-713-2897), or e-mailed 

(nos.coops.oetteam@noaa.gov) or mailed to ED. Test transmissions conducted on site are 

outside this requirement. This station and DCP information must be configured in DMS before 

data transmissions begin so that the all data will be accepted in DMS. The documentation 

required prior to transmission in field is defined in the NGWLMS Site Report, or Tide Station 
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Report, or Xpert Site Report, as appropriate. (Refer to Section 1.5 Data Submission 

Requirements). 

1.2.3 Station Installation, Operation and Removal 

Installer shall obtain all required permits and permissions for installation of the water level 

sensor(s), Data Collection Platforms (DCP), bench marks, and utilities, as required. The installer 

shall be responsible for security and/or protective measures, as required. The installer shall 

install all components in the manner prescribed by manufacturer, or installation manuals. The 

installer shall provide CO-OPS the position of all tide gauges installed, before the shoreline 

mapping survey begins, or during the survey, including those that were not specified in the 

Project Instructions, as appropriate. The positions of bench marks, sensors, and DCP installed or 

recovered shall be obtained and reported as latitudes and longitudes (degrees, minutes, seconds 

and tenth of seconds). 

The water level station and its various components (tide house, DCP, all sensors, bench marks, 

and pertinent access facilities such as railings, steps, etc., as appropriate), when designed or 

installed by contractors, shall be installed and maintained as prescribed by manufacturers, 

installation manuals, appropriate local building codes, or as specified by the Contracting 

Officer’s Technical Representative (COTR), if applicable. Water level station and all installed 

components shall be structurally sound for its intended application, secure, and safe to use for 

NOS, local partners, contractors, and general public, as appropriate. 

The following paragraphs provide general information regarding requirements for station 

installation, operations and maintenance, and station removal. 

1.2.3.1 Station Installation 

A complete water level measurement gauge installation shall consist of the following: 

A. The installation of the water level measurement system (water level sensor(s), DCP, and 

satellite transmitter, as appropriate) and its supporting structure and a tide staff, if 

required. 

B. The recovery and/or installation of a minimum number of bench marks and a level 

connection between the bench marks and the water level sensor(s), and tide staff as 

appropriate. The required minimum number of bench marks are specified in the “User’s 

Guide for the Installation of Bench marks and Leveling Requirements for Water Level 

Stations, NOAA/NOS, dated October 1987. 

C. The preparation of all documentation and forms. (See Section 1.5.3) 

1.2.3.2 Operation and Maintenance 

When GOES telemetry and NOS satellite message format is used for NOS in-house shoreline 

mapping surveys, the installer shall monitor the near-real time water level gauge data daily for 

indications of sensor malfunction or failure, and for other causes of degraded or invalid data, 
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such as marine fouling. This monitoring can be performed by accessing the COOPS web page 

(http://TidesandCurrents.noaa.gov). The data over this system are typically available for review 

within one to four hours after collection. 

All repairs, adjustments, replacements, cleaning, or other actions potentially affecting sensor 

output or collection of data shall be documented in writing using appropriate maintenance forms 

(see Section 1.5.1 on water level station documentation below) and retained as part of the water 

level data record. This documentation shall include, but not be limited to, the following 

information: date and time of start and completion of the maintenance activity; date and time of 

adjustments in sensor/DCP, datum offset, or time; personnel conducting the work; parts or 

components replaced; component serial numbers; tests performed; etc. 

For water level stations that are collecting data for more than six months duration, a check level 

is required at every six month duration from the installation of the gauge till the water level 

gauge is removed. See Section 1.2.5.4 Leveling Frequency for further details. 

1.2.3.3 Removal 

A complete removal of the water level measurement gauge shall consist of the following: 

A. Closing levels - a level connection between the minimum number of required bench 

marks and the water level sensor(s) and tide staff as appropriate. 

B. Removal of the water level measurement system and restoration of the premises, 

reasonable wear and tear accepted. 

C. The preparation of all documentation, forms, data, and reports. (See Section 1.5.3) 

1.2.4 Tide Staffs, Staff Observations, and Bubbler/Pressure Sensor Orifice 

1.2.4.1 Staff 

The installer shall install a tide staff at a station if the reference measurement point of a sensor 

(zero of a gauge) cannot be directly leveled to the local bench marks (e.g. orifice/pressure sensor 

has to be installed offshore on the sea floor). The tide staff is generally not required for acoustic 

gauges because the sensor elevation (the sensor zero reference point) can be measured during 

leveling. Even if a pressure gauge sensor elevation (the sensor zero reference point) can be 

leveled directly, staff readings shall still be required for assessment of variations in gauge 

performance due to density variations in the water column over time. The tide staff shall be 

mounted independent of the water level sensor so that stability of the staff or sensor is 

maintained. Staff shall not be mounted to the same pile on which the water level sensor is 

located. The staff shall be plumb. When two or more staff scales are joined to form a long staff, 

the installer shall take extra care to ensure the accuracy of the staff throughout its length. The 

distance between staff zero and the rod stop shall be measured before the staff is installed and 

after it is removed and the rod stop above staff zero height shall be reported on the 

documentation forms including leveling abstracts. 
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In areas of large tidal range and long sloping beaches (i.e. Cook Inlet, AK, and the Gulf of 

Maine), the installation and maintenance of tide staffs can be extremely difficult and costly. In 

these cases, the physical installation of a tide staff(s) may be substituted by systematic leveling to 

the water’s edge from the closest bench mark. The bench mark becomes the “staff stop” and the 

elevation difference to the water’s edge becomes the “staff reading”. 

1.2.4.2 Staff Observations 

When using the vented pressure sensor, a series of gauge/staff comparisons through a significant 

portion of a tidal cycle (minimum 3 hours) shall be required (1) at the start of water level data 

collection, (2) at frequent intervals during deployment, and (3) at the end of a deployment before 

gauge has been removed. Frequent gauge/staff comparisons during deployment shall be required 

to assist in assuring measurement stability and minimizing processing type errors. The staff to 

gauge observations at the start and end of deployment shall be at least each three hours long and 

the periodic observations during the deployment shall be at least 1 hour long. The staff to gauge 

observations shall be performed three times per week, during each week of the project, with at 

least one hour long observations of 6 minute intervals for each time. Where staff to gauge 

observations can not be performed three times a week as required then an explanation is required 

for the deficiency of number of observations and staff to gauge observations shall be performed 

at least (a) minimum eight times spread out over each month (e.g. two times per week) and at 

each time at least 1 hour of observations at 6 minute interval, or (b) minimum of four times 

spread out over each month (e.g. one time per week) and at each time at least 2 hours of 

observations at 6 minute interval, whichever is convenient. 

The staff to gauge differences should remain constant throughout the set of observations and 

show no increasing or decreasing trends. If the staff to gauge differences do not remain constant, 

then collected water level data may not be valid for deriving datums. After the water level data 

has been collected, the averaged staff-to-gauge shall be applied to water level measurements to 

relate the data to staff zero. A higher number of independent staff readings decrease the 

uncertainty in transferring the measurements to station datum and the bench marks. Refer to 

Figure 1.2 for an example pressure tide gauge record. 

If a tide staff is found destroyed by elements during the deployment, then a new staff shall be 

installed for the remainder period of the deployment and a new staff to gauge constant needs to 

be derived by new sets of staff to gauge observations. Also when a staff or an orifice is replaced 

or re-established, check levels shall be run to minimum of three bench marks including the 

Primary Bench Mark (PBM). Refer to Section 1.2.5 for leveling frequency and other leveling 

requirements. 

For water level historic stations that are reoccupied, CO-OPS will provide the station datum (SD) 

information for the station. This information is generally given for the PBM above the historic 

SD. In that case, for pressure sensors that require staff-to-gauge observations, all the water level 

data shall be placed on the station datum using the following equation: 

Water level data on the SD = (Preliminary pressure water level data on an arbitrary datum as 

collected by the gauge) + (PBM above SD) - (Staff zero below PBM) - (+/- weighted staff-togauge constant) 
Water Level Station Specifications and Deliverables

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Staff zero below PBM = (Staff stop below PBM) + (Staff zero below Staff stop) 

The staff to gauge constant shall be derived as a weighted average of all the staff to gauge 

readings done for the project, and staff to gauge constant shall be applied algebraically (with 

proper sign). The staff zero below PBM is obtained generally by (a) leveling from PBM to staff 

stop and (b) then measuring the staff stop to staff zero elevation with a steel tape and (c) then 

combining the two (a and b) elevation values. The staff zero below PBM is obtained by 

averaging the elevations differences during the opening (installation) and closing (removal) 

leveling runs for short term occupations. 

The orifice elevation above station datum is also defined as an accepted orifice offset in CO-OPS 

Data Management System (DMS). 
Water Level Station Specifications and Deliverables

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1.2.4.3 Bubbler Orifice and Parallel Plate Assembly 

This bottom assembly is made of red brass; its chemical properties prevent the growth of marine 

life by the slowly releasing copper oxide on its metal surface. A Swagelok® hose fitting is 

screwed into the top end cap and is used to discharge the Nitrogen gas. The Nitrogen gas flows 

through the bottom of the orifice at a rate sufficient to overcome the rate of tidal change and 

wave height. This opening establishes the reference point for tidal measurements. The parallel 

plates produce a laminar flow across the orifice to prevent the venturi effect. A two inch by eight 

inch pipe (as shown here) provides the correct volume gas for widest range of surf conditions 

encountered by most coastal surveys. 

Figure 1.1. Bubbler Orifice Bottom Assembly 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 13

 

PRESSURE TIDE GAUGE RECORD 

Station Name:_______________________ Station No. (7 digit #) _______________________ 

Date Time Staff Reading Gauge/Staff 

Difference 

Gas Pressure Wind 

(Dir/Spd) 

Air 

Temp. (M,D,Y) Gauge Correct High Low Cyln Feed Remarks 

 

Figure 1.2. Example – Pressure Tide Gauge Record 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 14

 

1.2.5 Bench Marks and Leveling 

1.2.5.1 Bench Marks 

According to NGS Geodetic Glossary a bench mark is a relatively permanent, natural or 

artificial, material object bearing a marked point whose elevation above or below an adopted 

surface (datum) is known. A bench mark is set for stability and used as a reference to the 

vertical and/or horizontal datums. 

Bench marks in the vicinity of a water level measurement station are used as the reference for the 

local tidal datums derived from the water level data. The relationship between these tidal bench 

marks and the water level sensor or tide staff shall be established by differential leveling. 

1.2.5.2 Number and Type of Bench Marks 

The number and type of bench marks required depends on the duration of the water level 

measurements. The User's Guide for the Installation of Bench Marks and Leveling Requirements 

for Water Level Stations, dated October 1987, which is available at the following URL: 

http://tidesandcurrents.noaa.gov/publications/users_guide_for_installation_of_Bench_Mark.pdf 

specifies the installation and documentation requirements for the bench marks. Each water level 

station will have one bench mark designated as the PBM, which shall be leveled to on every run. 

The PBM is typically the most stable mark in close proximity to the water level measurement 

station. The contractor shall select a PBM at sites where the PBM has not already been 

designated. For historic water level station reoccupations, CO-OPS will furnish the 

designation/stamping of the PBM and PBM elevation above station datum, if available. 

The most desirable bench mark for GPS observations will have 360 degrees of horizontal 

clearance around the mark at 10 degrees and greater above the horizon and stability code of A or 

B. Refer to User’s Guide for GPS Observations At Tide and Water Level Station Bench Marks, 

Updated November 2008 which is available at the following URL: 

http://tidesandcurrents.noaa.gov/pub.html for further information. 

If the PBM is determined to be unstable, another mark shall be designated as PBM. The date of 

change and the elevation difference between the old and new PBM shall be documented. NOAA 

will furnish the individual NOS standard bench mark disks to be installed. Bench mark 

descriptions shall be written according to User’s Guide for Writing Bench Mark Descriptions, 

updated January 2003 (http://tidesandcurrents.noaa.gov/publications/bmguide5.pdf). 

1.2.5.3 Leveling 

At least, geodetic third-order levels (refer to Reference 19, but 2nd order class I levels are 

preferred) shall be run at short-term subordinate stations operated for less than one-year. 

Requirements for higher order levels will be specified in individual project instructions, or 

statements of work, as appropriate. Standards and specifications for leveling are found in 

Standards and Specifications for Geodetic Control Networks and Geodetic Leveling (NOAA 

Manual NOS NGS 3) (http://www.ngs.noaa.gov/PUBS_LIB/Geodeticleveling_nos_3.pdf). 

Additional field requirements and procedures used for leveling at tide stations can be found in 
Water Level Station Specifications and Deliverables

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the User’s Guide for the Installation of Bench Marks and Leveling Requirements for Water Level 

Stations. Electronic digital/barcode level systems are preferable. 

Specifications and standards for digital levels can be found in Standards and Specifications for 

Geodetic Control Networks (http://www.ngs.noaa.gov/FGCS/tech_pub/1984-stds-specsgeodetic-control-networks.htm#3.5) and additional field requirements and procedures used by 

NOS for electronic leveling at water level stations can be found in the User’s Guide for 

Electronic Levels, updated January 2003, which is available at the following url: 

http://tidesandcurrents.noaa.gov/publications/laserlevelsguide.pdf . 

1.2.5.4 Leveling Frequency 

Levels shall be run between the water level sensor(s) or tide staff (depending on the type of 

gauge) and the required number of bench marks when the water level measurement station is 

installed, modified (e.g., water level sensor serviced, staff, or orifice replaced), for time series 

bracketing purposes, or prior to removal. In any case, levels are required at a maximum interval 

of six (6) months during the station's operation, and are required after severe storms, hurricanes, 

or earthquakes to document stability (see stability discussed below). 

1.2.5.5 Stability 

If there is an unresolved movement of the water level sensor or tide staff zero relative to the 

PBM, from one leveling to the next, of greater than 0.006 m, the leveling party shall verify the 

apparent movement by re-running the levels between the sensor zero or tide staff to the PBM and 

all the marks. The confirmation levels provide verification that sensor/bench mark indeed 

moved, or did not move. Since short term water level gauges generally do not have long term 

leveling history as do the NWLON permanent water level gauges, hence, the confirmation levels 

provide information that can be used to verify sensor/bench mark stability during the data 

processing. This threshold of 0.006 m should not be confused with the closure tolerances used 

for the order and class of leveling. 

1.2.6 Water Level Station Documentation 

The field team shall maintain a documentation package for each water level measurement station 

installed for shoreline mapping projects. The documentation package shall be forwarded after a) 

installation of a station, b) performance of bracketing levels, c) gauge maintenance and repair, or 

d) removal of the station. Refer to time frames for submission of documentation in Section 

1.5.3. 

Generally, all documentation (see Section 1.5 for Data Submission Requirements) shall be 

forwarded when a station is installed. For other situations, only information that has changed 

shall be submitted (e.g., levels and abstract for bracketing or removal levels, NGWLMS Site 

Report, or Tide Station Report, or Xpert Site Report, as appropriate, for maintenance and repair 

or station removal, etc.) Refer to Section 1.5.3 for documentation requirements. 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 16

 

1.2.7 Additional Field Requirements 

A. Complete data set must be sent as a batch for short term station (less than 6 months 

duration) installed. For long term stations submit water level data every 6 months till the 

gauge is removed unless the data are transmitted via satellite. The 6 month submission 

shall also include updated hourly heights, high/ low, monthly means, and datums. 

B. All water level data from a gauge shall be downloaded and backed up on electronic 

formats currently used such as CD-ROM or DVD-ROM, whether the gauge data are sent 

via satellite or not. 

C. For new water level stations that do not have station numbers assigned, once the location 

of the gauge has been finalized, then contact CO-OPS or COTR and provide latitude and 

longitude of the gauge site at least three business days prior to actual installation of the 

gauge in field. CO-OPS will assign a new station number within three business days and 

inform the installer. 

D. At each water level station, GPS observations at one bench mark shall be performed 

according to the most recent version of CO-OPS’ “User’s Guide for GPS Observations 

At Tide and Water level Station Bench Marks” 

(http://tidesandcurrents.noaa.gov/publications/Users_Guide_for_GPS_Observations_upd

ated_November_2008.pdf). 

1.3 Data Processing and Reduction 

1.3.1 Data Quality Control 

The required output product used in generation of tide control for the stage of tide and for tidal 

datum determination is a continuous time series of 6-minute interval water level data for the 

desired time period of survey and for a specified minimum time period from which to derive 

tidal datums. The 6-minute interval water level data from the water level gauges shall be quality 

controlled to NOS standards by the contractor for invalid and suspect data as a final review prior 

to product generation and submission to CO-OPS for data validation. This includes checking for 

data gaps, data discontinuities, datum shifts, anomalous data points, data points outside of 

expected tolerances such as expected maximum and minimum values and for anomalous trends 

in the elevations due to sensor drift or vertical movement of the tide station components and 

bench marks. 

Quality control shall include comparisons with simultaneous data from backup gauges, predicted 

tides or data from nearby stations, as appropriate. Data editing and gap filling shall use 

documented mathematically sound algorithms and procedures, and an audit trail shall be used to 

track all changes and edits to observed data. All inferred data shall be appropriately flagged. 

Water level measurements from each station shall be related to a single, common datum, referred 

to as Station Datum. Station Datum is an arbitrary datum and should not be confused with a tidal 

datum such as MLLW or a geodetic datum such as NAVD 88. All discontinuities, jumps, or 

other changes in the gauge record (refer to the specific gauge user’s guide) shall be fully 

documented. All data shall be recorded on Greenwich Mean Time (GMT) or Universal Time 
Water Level Station Specifications and Deliverables

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Coordinated (UTC) and the metric units of measurement shall be properly denoted on all hardcopy output and digital files. Refer to Section 1.5 Data Submission Requirements for details. 

Refer to Tidal Datums and Their Applications at 

http://tidesandcurrents.noaa.gov/publications/tidal_datums_and_their_applications.pdf and 

Computational Techniques for Tidal Datums Handbook at 

http://tidesandcurrents.noaa.gov/publications/Computational_Techniques_for_Tidal_Datums_ha

ndbook.pdf for additional information. 

1.3.2 Data Processing and Tabulation of the Tide 

The continuous 6-minute interval water level data are used to generate the standard tabulation 

output products. These products include the times and heights of the high and low waters, hourly 

heights, maximum and minimum monthly water levels, and monthly mean values for the desired 

parameters. Examples of these tabulation products are found in Figure 1.3 and 1.4 for tide 

stations and Figure 1.5 for Great Lakes stations. The times and heights of the high and low 

waters shall be derived from appropriate curve-fitting of the 6-minute interval data. For 

purposes of tabulation of the high and low tides and not non-tidal high frequency noise, 

successive high and low tides shall not be tabulated unless they are greater than 2.0 hours apart 

in time and 0.030 meters different in elevation. Hourly heights shall be derived from every 6-

minute value observed on the hour. Monthly mean sea level and monthly mean water level shall 

be computed from the average of the hourly heights over each calendar month of data. Data 

shall be tabulated relative to a documented consistent station datum such as tide staff zero, 

arbitrary station datum, MLLW, etc., over the duration of the data observations. Descriptions of 

general procedures used in tabulation are also found in the Tide and Current Glossary, Manual 

of Tide Observations, Tidal Datum Planes, and Computational Techniques for Tidal Datums 

Handbook. 

Refer to Tidal Datums and Their Applications at 

http://tidesandcurrents.noaa.gov/publications/tidal_datums_and_their_applications.pdf and 

Computational Techniques for Tidal Datums Handbook at 

http://tidesandcurrents.noaa.gov/publications/Computational_Techniques_for_Tidal_Datums_ha

ndbook.pdf for additional information. 

1.3.3 Computation of Monthly Means 

Monthly means are derived on a calendar month basis in accordance with the definitions for the 

monthly mean parameters as found in the Tide and Current Glossary. Examples of the desired 

monthly means are found in Figure 1.7. For purposes of monthly mean computation, monthly 

means shall not be computed if gaps in data are greater than three consecutive days. For partial 

month (any data less than full month) water level data, perform tide by tide comparison with the 

control station data. 
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1.3.4 Data Editing and Gap Filling Specifications 

When backup sensor data are not available, data gaps in 6-minute data shall not be filled if the 

gaps are greater than three consecutive days in length. Data gap filling shall use documented 

mathematically and scientifically sound algorithms and procedures and an audit trail shall be 

used to track all gap-fills in observed data. Data gaps of less than 3-hours can be inferred using 

interpolation, curve-fitting techniques, and predictions. Data gaps of longer than three hours but 

less than 3 days may use external data sources such as data from a nearby station, provided the 

data matches and there are no meteorological events during that gap. All data derived through 

gap-filling procedures shall be marked as inferred. Individual hourly heights, high and low 

waters, and daily means derived from inferred data shall also be designated as inferred. 
Water Level Station Specifications and Deliverables

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Jan 31 2007 14:09 HIGH/LOW WATER LEVEL DATA July, 1998 

 National Ocean Service (NOAA) 

 Station: 9414290 T.M.: 0 W 

 Name: SAN FRANCISCO, SAN FRANCISCO BAY, CA Units: Meters 

 Type: Mixed Datum: STND 

 Note: > Higher-High/Lower-Low [] Inferred Tide Quality: Verified 

 

 High Low High Low 

 Day Time Height Time Height Day Time Height Time Height 

 --- ---- ------ ---- ------ --- ---- ------ ---- ------ 

 1 > 1.4 3.337 6.8 2.521 16 > 0.6 3.550 6.2 2.343 

 12.6 2.996 > 18.5 2.253 12.6 3.187 > 18.1 2.195 

 2 > 2.0 3.393 7.8 2.434 17 > 1.4 3.654 7.4 2.205 

 13.9 2.950 > 19.4 2.406 14.1 3.096 19.0 2.335 

 3 > 2.6 3.458 > 9.1 2.367 18 > 2.2 3.725 > 8.6 2.054 

 15.2 2.941 20.1 2.498 15.6 3.132 20.2 2.504 

 4 > 3.2 3.524 > 9.7 2.210 19 > 3.1 3.819 > 9.7 1.891 

 16.5 2.988 21.1 2.612 16.9 3.188 21.5 2.586 

 5 > 4.0 3.584 > 10.3 2.018 20 > 4.1 3.899 > 10.7 1.763 

 17.6 3.054 22.0 2.644 18.0 3.267 22.5 2.597 

 6 > 4.6 3.656 > 11.1 1.913 21 > 4.9 3.903 > 11.6 1.654 

 18.3 3.124 22.7 2.682 18.8 3.309 23.4 2.583 

 7 > 5.1 3.711 > 11.8 1.812 22 > 6.0 3.884 

 19.1 3.194 23.4 2.697 19.6 3.347 > 12.4 1.587 

 8 > 5.8 3.754 23 > 6.4 3.880 0.2 2.587 

 19.7 3.223 > 12.4 1.730 20.3 3.390 > 13.1 1.611 

 9 > 6.3 3.789 0.1 2.703 24 > 7.4 3.833 1.1 2.586 

 20.4 3.285 > 13.1 1.669 20.9 3.409 > 13.9 1.659 

 10 > 7.3 3.795 0.9 2.709 25 > 8.1 3.780 1.7 2.562 

 21.1 3.306 > 13.7 1.627 21.6 3.445 > 14.5 1.719 

 11 > 8.0 3.712 1.6 2.614 26 > 8.7 3.668 2.6 2.564 

 21.7 3.302 > 14.4 1.579 22.2 3.437 > 14.9 1.826 

 12 > 8.8 3.639 2.5 2.584 27 > 9.3 3.510 3.2 2.549 

 22.3 3.356 > 15.1 1.609 > 22.8 3.416 > 15.6 1.932 

 13 > 9.3 3.547 3.1 2.530 28 10.1 3.356 4.1 2.538 

 23.1 3.419 > 15.6 1.692 > 23.5 3.430 > 16.1 2.042 

 14 10.1 3.443 4.1 2.522 29 10.9 3.202 5.0 2.495 

 > 23.9 3.484 > 16.5 1.800 > 16.6 2.199 

 15 11.3 3.282 5.1 2.422 30 > 0.1 3.432 5.9 2.492 

 > 17.0 1.967 12.0 3.099 > 17.3 2.402 

 31 > 0.8 3.472 > 6.9 2.431 

 13.1 3.018 18.5 2.513 

 

 Highest Tide: 3.903 4.9 Hrs Jul 21 1998 

 Lowest Tide: 1.579 14.4 Hrs Jul 11 1998 

 Monthly Means: MHHW 3.641 

 MHW 3.433 DHQ 0.208 

 MTL 2.832 GT 1.720 HWI 7.57 Hrs 

 DTL 2.781 MN 1.203 LWI 0.76 Hrs 

 MSL 2.816 

 MLW 2.230 DLQ 0.309 

 MLLW 1.921 

 

Figure 1.3. High and Low Water Level Data 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 20

 

HOURLY WATER LEVELS 

 National Ocean Service (NOAA) July 1998 

Water Level Heights in meters on Station Datum 

 

 Station: 9414290 SAN FRANCISCO, SAN FRANCISCO BAY , CA Time Meridian 0 W Tide Type: Mixed

_____________________________________________________________________________________________________________ 

HOUR Jul 1 Jul 2 Jul 3 Jul 4 Jul 5 Jul 6 Jul 7 Jul 8 Jul 9 Jul 10 Jul 11 Jul 12 Jul 13 Jul 14 Jul 15 Jul 16 

 00 3.247 3.183 3.119 3.052 2.936 2.837 2.770 2.724 2.717 2.763 2.814 2.960 3.152 3.354 3.481 3.529 

 01 3.329 3.333 3.319 3.274 3.157 3.066 2.972 2.851 2.762 2.694 2.637 2.723 2.901 3.162 3.365 3.517 

 02 3.311 3.391 3.449 3.437 3.378 3.293 3.173 3.060 2.913 2.799 2.627 2.602 2.653 2.868 3.123 3.395 

 03 3.164 3.312 3.463 3.526 3.526 3.504 3.423 3.298 3.171 2.988 2.750 2.618 2.529 2.621 2.792 3.103 

 04 2.948 3.158 3.338 3.469 3.595 3.629 3.617 3.555 3.420 3.261 2.985 2.755 2.606 2.523 2.523 2.741 

 05 2.725 2.914 3.091 3.304 3.474 3.628 3.714 3.707 3.652 3.519 3.247 3.012 2.757 2.576 2.423 2.459 

 06 2.558 2.651 2.811 3.012 3.209 3.430 3.640 3.740 3.782 3.711 3.508 3.252 2.986 2.745 2.472 2.302 

 07 2.528 2.451 2.531 2.651 2.833 3.112 3.342 3.580 3.746 3.785 3.668 3.485 3.217 2.954 2.619 2.399 

 08 2.581 2.453 2.387 2.366 2.448 2.653 2.915 3.225 3.496 3.677 3.715 3.628 3.433 3.155 2.804 2.480 

 09 2.648 2.510 2.375 2.228 2.133 2.243 2.435 2.701 3.060 3.348 3.540 3.626 3.535 3.354 2.997 2.651 

 10 2.778 2.568 2.400 2.229 2.017 1.994 2.057 2.236 2.477 2.819 3.159 3.410 3.510 3.444 3.185 2.870 

 11 2.890 2.696 2.494 2.280 2.057 1.909 1.859 1.919 2.081 2.327 2.576 2.970 3.257 3.389 3.283 3.040 

 12 2.976 2.813 2.643 2.431 2.159 1.972 1.826 1.719 1.774 1.922 2.101 2.422 2.818 3.165 3.248 3.162 

 13 2.995 2.917 2.750 2.581 2.327 2.124 1.913 1.756 1.674 1.667 1.781 2.000 2.350 2.735 3.051 3.175 

 14 2.904 2.945 2.897 2.760 2.559 2.338 2.117 1.908 1.744 1.633 1.588 1.706 1.946 2.305 2.737 3.069 

 15 2.742 2.903 2.922 2.898 2.778 2.611 2.387 2.154 1.944 1.759 1.625 1.612 1.732 1.965 2.365 2.831 

 16 2.505 2.783 2.909 2.986 2.937 2.862 2.683 2.455 2.260 2.014 1.791 1.690 1.697 1.794 2.053 2.492 

 17 2.359 2.594 2.814 2.976 3.040 3.034 2.954 2.786 2.585 2.366 2.084 1.911 1.852 1.854 1.971 2.258 

 18 2.250 2.473 2.649 2.915 3.028 3.137 3.124 3.015 2.936 2.739 2.449 2.242 2.074 1.986 2.020 2.177 

 19 2.272 2.401 2.550 2.773 2.960 3.099 3.190 3.187 3.141 3.021 2.814 2.618 2.419 2.256 2.193 2.269 

 20 2.336 2.413 2.484 2.647 2.812 2.990 3.149 3.215 3.271 3.239 3.094 2.975 2.797 2.595 2.462 2.415 

 21 2.508 2.514 2.527 2.637 2.690 2.843 2.999 3.128 3.251 3.310 3.275 3.220 3.131 2.954 2.781 2.677 

 22 2.736 2.685 2.631 2.636 2.634 2.709 2.835 2.982 3.130 3.233 3.280 3.369 3.339 3.242 3.104 2.961 

 23 2.965 2.912 2.814 2.752 2.703 2.700 2.688 2.779 2.916 3.063 3.177 3.322 3.422 3.417 3.336 3.284 

Mean 2.761 2.791 2.807 2.826 2.808 2.822 2.824 2.820 2.829 2.819 2.762 2.755 2.755 2.767 2.766 2.802 

HOUR Jul 17 Jul 18 Jul 19 Jul 20 Jul 21 Jul 22 Jul 23 Jul 24 Jul 25 Jul 26 Jul 27 Jul 28 Jul 29 Jul 30 Jul 31 

 00 3.514 3.373 3.180 2.993 2.778 2.625 2.586 2.678 2.821 3.048 3.228 3.317 3.411 3.444 3.438 

 01 3.654 3.617 3.485 3.264 3.035 2.810 2.649 2.586 2.613 2.749 2.951 3.122 3.270 3.357 3.466 

 02 3.620 3.720 3.720 3.573 3.322 3.071 2.848 2.682 2.573 2.590 2.680 2.834 3.030 3.195 3.394 Monthly 

 03 3.427 3.686 3.818 3.785 3.641 3.379 3.133 2.884 2.694 2.576 2.550 2.625 2.735 2.937 3.148 Max HWL 

 04 3.111 3.433 3.737 3.907 3.840 3.659 3.444 3.201 2.926 2.761 2.591 2.538 2.547 2.704 2.888 04:54/21 

 05 2.704 3.048 3.487 3.775 3.898 3.849 3.697 3.460 3.206 2.978 2.759 2.586 2.487 2.523 2.660 3.903 

 06 2.398 2.607 3.017 3.452 3.745 3.887 3.866 3.717 3.505 3.247 2.976 2.757 2.553 2.486 2.467 

 07 2.215 2.254 2.539 2.948 3.376 3.678 3.851 3.828 3.704 3.501 3.210 2.928 2.697 2.545 2.448 

 08 2.255 2.073 2.167 2.436 2.810 3.269 3.593 3.770 3.778 3.652 3.390 3.150 2.860 2.659 2.477 Monthly 

 09 2.319 2.064 1.953 2.018 2.299 2.662 3.083 3.430 3.637 3.659 3.504 3.302 3.031 2.809 2.571 Min LWL 

 10 2.483 2.155 1.884 1.806 1.896 2.146 2.526 2.942 3.284 3.486 3.479 3.358 3.144 2.948 2.725 14:24/11 

 11 2.691 2.304 1.993 1.757 1.696 1.794 2.071 2.397 2.758 3.107 3.252 3.294 3.203 3.055 2.856 1.579 

 12 2.876 2.544 2.195 1.877 1.664 1.603 1.743 1.981 2.282 2.618 2.907 3.090 3.119 3.107 2.975 

 13 3.037 2.784 2.453 2.094 1.808 1.637 1.621 1.723 1.924 2.215 2.471 2.741 2.953 3.037 3.031 

 14 3.088 2.995 2.738 2.387 2.076 1.816 1.662 1.644 1.740 1.919 2.149 2.402 2.658 2.905 2.975 Monthly 

 15 3.038 3.104 2.978 2.738 2.434 2.122 1.918 1.797 1.762 1.827 1.956 2.144 2.396 2.676 2.908 Mean 

 16 2.880 3.119 3.134 3.028 2.790 2.510 2.249 2.056 1.942 1.882 1.950 2.016 2.231 2.493 2.725 MSL 

 17 2.621 3.011 3.191 3.220 3.078 2.887 2.646 2.422 2.219 2.117 2.061 2.118 2.218 2.398 2.595 2.816 

 18 2.400 2.812 3.107 3.284 3.266 3.162 3.018 2.791 2.604 2.412 2.302 2.244 2.299 2.432 2.508 

 19 2.323 2.600 2.938 3.179 3.300 3.316 3.273 3.162 2.978 2.775 2.615 2.496 2.465 2.490 2.527 

 20 2.402 2.513 2.731 3.013 3.210 3.336 3.394 3.345 3.271 3.109 2.939 2.795 2.688 2.663 2.620 

 21 2.554 2.550 2.605 2.755 3.012 3.214 3.345 3.401 3.415 3.335 3.215 3.075 2.963 2.884 2.766 

 22 2.789 2.698 2.619 2.612 2.735 2.975 3.189 3.316 3.427 3.428 3.369 3.310 3.184 3.109 2.984 

 23 3.073 2.920 2.760 2.631 2.613 2.707 2.912 3.118 3.300 3.400 3.407 3.429 3.373 3.308 3.178 

Mean 2.811 2.833 2.851 2.855 2.847 2.838 2.847 2.847 2.848 2.850 2.830 2.820 2.813 2.840 2.847 

 [ ] denotes inferred water level values Data Status: Verified 

Figure 1.4. Hourly Height Water Level Data for a Tide Station 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 21

 

HOURLY WATER LEVELS 

 National Ocean Service (NOAA) July 1998 

Water Level Heights in meters IGLD (1985) 

 

 Station: 9052030 Oswego, Lake Ontario , NY Time Meridian: 75 W Data Type: Great Lakes 

_______________________________________________________________________________________________________________ 

HOUR Jul 1 Jul 2 Jul 3 Jul 4 Jul 5 Jul 6 Jul 7 Jul 8 Jul 9 Jul 10 Jul 11 Jul 12 Jul 13 Jul 14 Jul 15 Jul 16 

 01 75.21 75.21 75.19 75.18 75.19 75.17 75.15 75.17 75.17 75.20 75.21 75.21 75.20 75.17 75.17 75.17 

 02 75.25 75.21 75.19 75.19 75.22 75.14 75.17 75.16 75.19 75.19 75.20 75.22 75.18 75.17 75.18 75.16 

 03 75.26 75.21 75.19 75.17 75.19 75.18 75.18 75.16 75.16 75.19 75.21 75.19 75.18 75.18 75.15 75.17 

 04 75.25 75.20 75.19 75.20 75.21 75.18 75.17 75.16 75.17 75.20 75.21 75.18 75.17 75.18 75.16 75.16 

 05 75.25 75.21 75.20 75.19 75.21 75.18 75.17 75.20 75.20 75.18 75.21 75.20 75.19 75.17 75.19 75.16 

 06 75.25 75.21 75.19 75.20 75.20 75.19 75.17 75.16 75.19 75.20 75.20 75.20 75.17 75.17 75.14 75.15 

 07 75.25 75.20 75.19 75.19 75.19 75.17 75.18 75.20 75.20 75.19 75.21 75.20 75.18 75.17 75.14 75.17 

 08 75.24 75.21 75.19 75.21 75.20 75.17 75.17 75.14 75.19 75.20 75.22 75.20 75.19 75.15 75.18 75.15 

 09 75.24 75.21 75.19 75.20 75.19 75.19 75.16 75.17 75.18 75.18 75.22 75.20 75.19 75.18 75.16 75.14 

 10 75.24 75.20 75.19 75.18 75.19 75.18 75.16 75.20 75.17 75.20 75.22 75.22 75.18 75.18 75.17 75.16 

 11 75.23 75.19 75.17 75.18 75.20 75.18 75.15 75.15 75.19 75.20 75.22 75.20 75.19 75.18 75.16 75.15 

 12 75.22 75.21 75.18 75.18 75.17 75.17 75.17 75.16 75.17 75.19 75.22 75.20 75.18 75.18 75.17 75.16 

 13 75.22 75.20 75.18 75.19 75.18 75.16 75.16 75.15 75.17 75.18 75.21 75.19 75.19 75.17 75.16 75.16 

 14 75.23 75.20 75.19 75.21 75.18 75.19 75.14 75.15 75.16 75.18 75.20 75.22 75.17 75.17 75.18 75.17 

 15 75.22 75.21 75.17 75.19 75.17 75.15 75.14 75.18 75.17 75.19 75.20 75.18 75.18 75.17 75.17 75.17 

 16 75.21 75.20 75.19 75.18 75.19 75.16 75.18 75.18 75.17 75.19 75.19 75.19 75.17 75.16 75.16 75.16 

 17 75.21 75.20 75.20 75.21 75.20 75.17 75.17 75.18 75.17 75.19 75.20 75.18 75.17 75.17 75.17 75.15 

 18 75.22 75.20 75.20 75.21 75.21 75.20 75.18 75.18 75.15 75.17 75.20 75.18 75.16 75.15 75.16 75.16 

 19 75.21 75.20 75.19 75.21 75.19 75.19 75.18 75.20 75.18 75.22 75.19 75.19 75.17 75.16 75.16 75.17 

 20 75.20 75.22 75.19 75.25 75.19 75.17 75.18 75.18 75.20 75.22 75.20 75.20 75.16 75.16 75.16 75.13 

 21 75.20 75.18 75.18 75.15 75.19 75.19 75.15 75.19 75.22 75.18 75.21 75.19 75.18 75.16 75.15 75.17 

 22 75.21 75.20 75.17 75.17 75.19 75.18 75.19 75.17 75.23 75.20 75.21 75.19 75.18 75.18 75.15 75.13 

 23 75.20 75.19 75.17 75.24 75.19 75.16 75.18 75.19 75.22 75.22 75.21 75.17 75.18 75.16 75.17 75.13 

 24 75.21 75.20 75.17 75.20 75.18 75.17 75.17 75.19 75.18 75.21 75.21 75.18 75.18 75.15 75.16 75.15 

Mean 75.23 75.20 75.19 75.19 75.19 75.18 75.17 75.17 75.18 75.20 75.21 75.19 75.18 75.17 75.16 75.16 

HOUR Jul 17 Jul 18 Jul 19 Jul 20 Jul 21 Jul 22 Jul 23 Jul 24 Jul 25 Jul 26 Jul 27 Jul 28 Jul 29 Jul 30 Jul 31 

 01 75.17 75.17 75.14 75.12 75.13 75.14 75.11 75.16 75.14 75.11 75.09 75.07 75.07 75.10 75.09 

 02 75.17 75.18 75.14 75.16 75.12 75.16 75.12 75.16 75.14 75.10 75.08 75.09 75.06 75.11 75.08 

 03 75.16 75.19 75.15 75.15 75.11 75.16 75.12 75.15 75.13 75.10 75.08 75.06 75.06 75.10 75.08 Monthly 

 04 75.17 75.18 75.14 75.14 75.13 75.15 75.10 75.14 75.14 75.10 75.07 75.09 75.02 75.09 75.08 Max HWL 

 05 75.16 75.18 75.16 75.13 75.14 75.13 75.14 75.16 75.13 75.10 75.06 75.11 75.07 75.08 75.08 03:00/01 

 06 75.17 75.16 75.15 75.16 75.10 75.17 75.12 75.16 75.12 75.10 75.06 75.07 75.16 75.07 75.08 75.259 

 07 75.16 75.16 75.17 75.14 75.12 75.13 75.14 75.14 75.13 75.10 75.07 75.06 75.14 75.07 75.07 

 08 75.16 75.16 75.14 75.15 75.15 75.12 75.14 75.16 75.13 75.10 75.06 75.08 75.11 75.05 75.07 

 09 75.15 75.15 75.11 75.14 75.12 75.20 75.15 75.17 75.13 75.11 75.06 75.06 75.10 75.08 75.07 Monthly 

 10 75.16 75.15 75.11 75.14 75.11 75.18 75.10 75.15 75.13 75.12 75.08 75.07 75.11 75.07 75.06 Min LWL 

 11 75.16 75.16 75.13 75.14 75.11 75.16 75.11 75.16 75.12 75.11 75.08 75.06 75.11 75.06 75.07 04:00/29 

 12 75.16 75.17 75.16 75.14 75.12 75.12 75.13 75.14 75.11 75.11 75.09 75.07 75.12 75.10 75.07 75.021 

 13 75.16 75.15 75.14 75.14 75.12 75.14 75.13 75.14 75.11 75.10 75.07 75.05 75.08 75.08 75.07 

 14 75.16 75.17 75.13 75.15 75.10 75.11 75.14 75.14 75.10 75.11 75.06 75.08 75.08 75.08 75.06 

 15 75.17 75.16 75.13 75.13 75.12 75.12 75.12 75.13 75.11 75.09 75.07 75.06 75.07 75.08 75.05 Monthly 

 16 75.16 75.16 75.13 75.13 75.13 75.14 75.14 75.13 75.12 75.09 75.08 75.05 75.09 75.05 75.06 Mean 

 17 75.18 75.16 75.13 75.13 75.08 75.11 75.16 75.13 75.10 75.07 75.08 75.07 75.08 75.09 75.06 MSL 

 18 75.17 75.15 75.14 75.16 75.12 75.13 75.13 75.13 75.10 75.07 75.08 75.06 75.08 75.09 75.06 75.152 

 19 75.16 75.16 75.13 75.14 75.11 75.11 75.10 75.14 75.10 75.08 75.06 75.05 75.07 75.09 75.06 

 20 75.17 75.16 75.16 75.15 75.12 75.13 75.16 75.14 75.11 75.09 75.06 75.07 75.09 75.07 75.06 

 21 75.18 75.14 75.11 75.13 75.16 75.12 75.17 75.14 75.11 75.08 75.07 75.05 75.09 75.07 75.04 

 22 75.18 75.15 75.14 75.13 75.10 75.15 75.17 75.14 75.11 75.08 75.07 75.06 75.09 75.08 75.06 

 23 75.18 75.14 75.14 75.12 75.09 75.14 75.18 75.14 75.11 75.08 75.09 75.05 75.10 75.08 75.05 

 24 75.19 75.14 75.11 75.11 75.09 75.12 75.17 75.15 75.11 75.09 75.10 75.08 75.09 75.09 75.06 

Mean 75.17 75.16 75.14 75.14 75.12 75.14 75.14 75.15 75.12 75.10 75.07 75.07 75.09 75.08 75.07 

 [ ] denotes inferred water level values Data Status: Verified 

Figure 1.5. Hourly Height Water Level Data for a Great Lakes Station
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 22

 

1.4 Computation of Tidal Datums and Water Level Datums 

1.4.1 National Tidal Datum Epoch 

Tidal datums shall be computed relative to a specific 19 year tidal cycle adopted by the NOS 

called the National Tidal Datum Epoch (NTDE). The present NTDE is the period 1983 through 

2001. A primary datum determination is based directly on the average of tide observations over 

the 19 year Epoch period at NOS permanent long term primary control stations in the National 

Water Level Observation Network (NWLON). The data from NOS primary stations are used to 

compute datums at short term subordinate stations by reducing the data from those subordinate 

stations to equivalent 19 year mean values through the method of comparison of simultaneous 

observation. 

1.4.2 Computational Procedures 

The equivalent 19 year tidal datums for subordinate stations are computed for certain phases of 

the tide using tide-by-tide comparisons or monthly mean comparisons with an appropriate NOS 

long term control station. Accepted 19 year mean values of mean tide level (MTL), mean range 

(MN), diurnal high water inequality (DHQ), diurnal low water inequality (DLQ), diurnal tide 

level (DTL), and great diurnal range (GT) are required in the reduction process in which a “short 

series” of tide observations at any location are compared with simultaneous observations from an 

NOS control station. Datums are computed by the “standard” method of range ratio comparison 

generally on the West coast and Pacific Islands where there exists a large diurnal inequality in 

the low and high waters. The “modified” method of range ratio comparison is generally used on 

the East coast and Caribbean where small differences exist in the low and high water diurnal 

inequalities. For stations requiring a datum determination, at least 30 continuous days of tide 

observations are required for stations where adequate primary datum control exists. For error 

budget purposes, one month of data results in a datum accuracy of 0.11 m (95% confidence 

level) for Stations in the Gulf of Mexico and 0.08 m (95% confidence level) for east and West 

Coast stations. Examples of a tide by tide and a monthly mean simultaneous comparison for 

datum determination are found in Figures 1.6 and 1.7. 

Descriptions of the tidal datum computational procedures are found in the Tide and Current 

Glossary (http://tidesandcurrents.noaa.gov/publications/glossary2.pdf), Tidal Datum Planes, 

Manual of Tide Observations, NOAA Special Publication NOS CO-OPS 1 Tidal Datums and 

Their Applications 

(http://tidesandcurrents.noaa.gov/publications/tidal_datums_and_their_applications.pdf) and 

Computational Techniques for Tidal Datums Handbook 

(http://tidesandcurrents.noaa.gov/publications/Computational_Techniques_for_Tidal_Datums_h

andbook.pdf). 

1.4.3 Tidal Datum Recovery 

Whenever tide stations are installed at historical sites, measures shall be taken to “recover” the 

established tidal datums through leveling which shall be accomplished by referencing the gauge 

or tide staff zero (“0") to more than one existing bench mark (three bench marks are required) 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 23

 

with a published tidal elevation. Through this process, the published MLLW elevation is 

transferred by level differences to the “new” gauge or tide staff and compared to the MLLW 

elevation computed from the new data on the same zero (“0"). Factors affecting the datum 

recovery (i.e. differences between old and newly computed datums) include the length of each 

data series used to compute the datums, the geographical location, the tidal characteristics in the 

region, the length of time between reoccupations, the sea level trends in the region, land level 

trends, and the control station used. Based on all of these factors, the datum recovery can be 

expected to vary from +/- 0.03 m to +/- 0.08 m. Thus successful datum recovery is defined as 

the difference of 8 cm or less between the old and newly computed datums. After a successful 

datum recovery is performed and benchmark stability is established, the historical value of Mean 

Lower Low Water (MLLW) and Mean High Water (MHW) shall be used as the operational 

datum reference for data from the gauge during shoreline mapping survey operations. Hence, this 

process also serves as a very useful quality control procedure. In case of unsuccessful datum 

recovery, CO-OPS will evaluate all the factors and determine whether the data is acceptable or 

not. An example of a published tidal datum sheet for a station for which a datum recovery could 

be made is found in Figure 1.8. 

1.4.4 Datum Quality Control 

It is essential for tidal datum quality control to have data processing and leveling procedures 

carried out as specified. Caution must also be used in computing tidal datums in rivers, 

tributaries, or in regions of unknown tidal regimes. Tide-by-tide comparisons between 

subordinate and control station data will often detect anomalous differences which should be 

investigated for possible gauge malfunction or sensor movement. Differences in elevations 

between bench marks based on new leveling must agree with previously established differences 

from the published bench mark sheets unless marks are destroyed or marks are disturbed by 

earthquakes, hurricanes, etc. Any changes in the elevation differences must be reconciled before 

using in any datum recovery procedure. Datum accuracy at a subordinate station depends on 

various factors, but availability and choice of an adequate control station of similar tidal 

characteristics, similar daily mean sea level and seasonal mean sea level variations, and similar 

sea level trends are the most important. The length of series will also determine accuracy. The 

longer the series, the more accurate the datum and the greater quality control and confidence 

gained from analyzing numerous monthly mean differences between the subordinate and control 

station. At reoccupied historical stations for which datum recoveries are made, updated datums 

shall be computed from the new time series and compared with the historical datums as the 

survey progresses. 

 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 24

Begin: Jun 15 2005 00:00 COMPARISON OF SIMULTANEOUS OBSERVATIONS Tidal Epoch: End: Jul 14 2005 23:54 Expected DiffRun: Jan 31 2007 16:30 * Exceeds 2 S (A) Subordinate Station: 9414863 RICHMOND, CHEVRON OIL PIER Verified T.M.: 0W Tide Type: (B) Standard Station: 9414290 SAN FRANCISCO, SAN FRANCISCO BAY Verified T.M.: 0W Tide Type:    (A) STATION (B) STATION (A) - (B) (A) STATION (B) STATION (A Time of Time of Time Difference Height of Height of Height  HW LW HW LW HW LW HW LW HW LW HW 2005 Hour Date Hour Date Hour Date Hour Hours Hours Meters Meters Meters Meters Meter------ ---- ------ ---- ------ ---- ------ ---- ------ ------ ------- ------- ------- ------- ------Jun 15 2.3 HH Jun 15 8.4 L Jun 15 2.0 HH Jun 15 7.5 L 0.3 0.9 5.091 4.266 3.304 2.546 1.78Jun 15 13.6 H Jun 15 19.7 LL Jun 15 13.2 H Jun 15 19.0 LL 0.4 0.7 4.745 3.890 2.970 2.222 1.77Jun 16 3.0 HH Jun 16 9.3 L Jun 16 2.5 HH Jun 16 8.4 L 0.5 0.9 5.193 4.065 3.412 2.362 1.78Jun 16 15.0 H Jun 16 20.5 L Jun 16 14.6 H Jun 16 19.7 L 0.4 0.8 4.731 4.070 2.953 2.350 1.77Jun 17 3.4 HH Jun 17 10.0 LL Jun 17 3.0 HH Jun 17 9.1 LL 0.4 0.9 5.347 3.861 3.566 2.144 1.78Jun 17 16.1 H Jun 17 21.4 L Jun 17 15.7 H Jun 17 20.6 L 0.4 0.8 4.736 4.140 2.960 2.418 1.77Jun 18 4.0 HH Jun 18 10.8 LL Jun 18 3.5 HH Jun 18 10.1 LL 0.5 0.7 5.400 3.657 3.612 1.919 1.78Jun 18 17.4 H Jun 18 22.2 L Jun 18 17.0 H Jun 18 21.6 L 0.4 0.6 4.793 4.265 3.015 2.539 1.77Jun 19 4.5 HH Jun 19 11.8 LL Jun 19 4.1 HH Jun 19 11.1 LL 0.4 0.7 5.528 3.440 3.728 1.714 1.80Jun 19 18.6 H Jun 19 23.0 L Jun 19 18.1 H Jun 19 22.4 L 0.5 0.6 4.833 4.365 3.057 2.626 1.77Jun 20 5.2 HH Jun 20 12.6 LL Jun 20 5.0 HH Jun 20 11.9 LL 0.2* 0.7 5.603 3.249 3.806 1.503 1.79Jun 20 19.5 H Jun 20 23.8 L Jun 20 19.1 H Jun 20 23.2 L 0.4 0.6 4.893 4.452 3.107 2.722 1.78Jun 21 5.8 HH Jun 21 13.4 LL Jun 21 5.5 HH Jun 21 12.9 LL 0.3 0.5 5.681 3.127 3.887 1.368 1.79Jun 21 20.4 H Jun 22 0.6 L Jun 21 20.1 H Jun 22 0.1 L 0.3 0.5 4.961 4.482 3.167 2.753 1.79Jun 22 6.5 HH Jun 22 14.2 LL Jun 22 6.2 HH Jun 22 13.6 LL 0.3 0.6 5.727 3.026 3.933 1.248 1.79Jun 22 21.3 H Jun 23 1.6 L Jun 22 20.9 H Jun 23 1.0 L 0.4 0.6 4.984 4.498 3.192 2.766 1.79Jun 23 7.6 HH Jun 23 15.0 LL Jun 23 7.2 HH Jun 23 14.4 LL 0.4 0.6 5.736 2.999 3.936 1.230 1.80Jun 23 22.1 H Jun 24 2.5 L Jun 23 21.7 H Jun 24 1.9 L 0.4 0.6 5.024 4.476 3.230 2.755 1.79Jun 24 8.2 HH Jun 24 15.9 LL Jun 24 7.8 HH Jun 24 15.1 LL 0.4 0.8 5.711 3.054 3.935 1.307 1.77Jun 24 22.9 H Jun 25 3.5 L Jun 24 22.3 H Jun 25 2.9 L 0.6 0.6 5.084 4.436 3.309 2.714 1.77Jun 25 9.2 HH Jun 25 16.6 LL Jun 25 8.8 HH Jun 25 15.7 LL 0.4 0.9 5.615 3.164 3.839 1.415 1.77Jun 25 23.7 H Jun 26 4.5 L Jun 25 23.1 H Jun 26 4.0 L 0.6 0.5 5.165 4.387 3.394 2.678 1.77Jun 26 10.3 HH Jun 26 17.5 LL Jun 26 9.9 HH Jun 26 16.6 LL 0.4 0.9 5.453 3.316 3.674 1.577 1.77Jun 27 0.4 H Jun 27 5.7 L Jun 26 23.7 HH Jun 27 5.1 L 0.7* 0.6 5.243 4.299 3.477 2.579 1.76Jun 27 11.4 HH Jun 27 18.1 LL Jun 27 10.8 H Jun 27 17.3 LL 0.6 0.8 5.257 3.478 3.467 1.744 1.79Jun 28 1.2 HH Jun 28 6.9 L Jun 28 0.6 HH Jun 28 6.4 L 0.6 0.5 5.313 4.167 3.538 2.451 1.77Jun 28 12.6 H Jun 28 18.7 LL Jun 28 12.1 H Jun 28 18.1 LL 0.5 0.6 5.007 3.639 3.217 1.921 1.79Jun 29 1.9 HH Jun 29 8.2 L Jun 29 1.4 HH Jun 29 7.5 L 0.5 0.7 5.381 3.997 3.591 2.274 1.79Jun 29 14.0 H Jun 29 19.5 LL Jun 29 13.6 H Jun 29 18.9 LL 0.4 0.6 4.883 3.908 3.094 2.210 1.78Jun 30 2.6 HH Jun 30 9.3 LL Jun 30 2.1 HH Jun 30 8.7 LL 0.5 0.6 5.486 3.850 3.711 2.119 1.77Jun 30 15.6 H Jun 30 20.6 L Jun 30 15.2 H Jun 30 20.1 L 0.4 0.5 4.824 4.151 3.047 2.445 1.77Jul 1 3.3 HH Jul 1 10.3 LL Jul 1 2.9 HH Jul 1 9.8 LL 0.4 0.5 5.521 3.694 3.741 1.957 1.78Jul 1 17.1 H Jul 1 21.8 L Jul 1 16.7 H Jul 1 21.2 L 0.4 0.6 4.867 4.347 3.083 2.625 1.78Jul 2 4.2 HH Jul 2 11.3 LL Jul 2 3.7 HH Jul 2 10.7 LL 0.5 0.6 5.554 3.565 3.768 1.816 1.78Jul 2 18.4 H Jul 2 22.7 L Jul 2 17.9 H Jul 2 22.2 L 0.5 0.5 4.943 4.500 3.152 2.770 1.79Jul 3 4.7 HH Jul 3 12.2 LL Jul 3 4.3 HH Jul 3 11.5 LL 0.4 0.7 5.590 3.464 3.809 1.712 1.78Jul 3 19.4 H Jul 3 23.5 L Jul 3 18.9 H Jul 3 23.1 L 0.5 0.4 4.963 4.519 3.180 2.797 1.78Jul 4 5.6 HH Jul 4 12.9 LL Jul 4 5.1 HH Jul 4 12.2 LL 0.5 0.7 5.571 3.379 3.782 1.637 1.78

Jul 4 20.1 H Jul 5 0.4 L Jul 4 19.6 H Jul 4 23.9 L 0.5 0.5 5.016 4.579 3.230 2.853 1.78Jul 5 6.0 HH Jul 5 13.5 LL Jul 5 5.5 HH Jul 5 12.7 LL 0.5 0.8 5.540 3.354 3.751 1.598 1.78Jul 5 20.9 H Jul 6 1.2 L Jul 5 20.3 H Jul 6 0.6 L 0.6 0.6 5.029 4.598 3.244 2.861 1.78Jul 6 6.9 HH Jul 6 14.1 LL Jul 6 6.3 HH Jul 6 13.5 LL 0.6 0.6 5.521 3.354 3.734 1.601 1.78Jul 6 21.5 H Jul 7 1.9 L Jul 6 20.9 H Jul 7 1.3 L 0.6 0.6 5.056 4.584 3.272 2.860 1.78

Figure 1.6. Tide-By-Tide Comparison 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 25

 Begin: Jun 15 2005 00:00 COMPARISON OF SIMULTANEOUS OBSERVATIONS Tidal Epoch:  End: Jul 14 2005 00:00 Expected Dif Run: Jan 31 2007 16:30 * Exceeds 2   (A) Subordinate Station: 9414863 RICHMOND, CHEVRON OIL PIER Verified T.M.: 0W Tide Type: 

(B) Standard Station: 9414290 SAN FRANCISCO, SAN FRANCISCO BAY Verified T.M.: 0W Tide Type: 

   (A) STATION (B) STATION (A) - (B) (A) STATION (B) STATION ( Time of Time of Time Difference Height of Height of Heigh HW LW HW LW HW LW HW LW HW LW HW  2005 Hour Date Hour Date Hour Date Hour Hours Hours Meters Meters Meters Meters Mete ------ ---- ------ ---- ------ ---- ------ ---- ------ ------ ------- ------- ------- ------- ----- Jul 7 7.4 HH Jul 7 14.8 LL Jul 7 7.2 HH Jul 7 13.9 LL 0.2* 0.9 5.510 3.380 3.715 1.622 1.7 Jul 7 22.0 H Jul 8 2.4 L Jul 7 21.4 H Jul 8 1.9 L 0.6 0.5 5.037 4.533 3.248 2.822 1.7 Jul 8 8.0 HH Jul 8 15.3 LL Jul 8 7.6 HH Jul 8 14.5 LL 0.4 0.8 5.444 3.397 3.660 1.654 1.7 Jul 8 22.5 H Jul 9 3.0 L Jul 8 21.9 H Jul 9 2.4 L 0.6 0.6 5.016 4.478 3.225 2.775 1.7 Jul 9 8.7 HH Jul 9 15.8 LL Jul 9 8.2 HH Jul 9 15.1 LL 0.5 0.7 5.375 3.453 3.587 1.719 1.7 Jul 9 23.1 H Jul 10 3.7 L Jul 9 22.5 H Jul 10 3.2 L 0.6 0.5 5.036 4.462 3.245 2.760 1.7 Jul 10 9.5 HH Jul 10 16.2 LL Jul 10 8.9 HH Jul 10 15.5 LL 0.6 0.7 5.267 3.541 3.476 1.802 1.7 Jul 10 23.6 H Jul 11 4.5 L Jul 10 23.1 H Jul 11 4.0 L 0.5 0.5 5.059 4.432 3.260 2.728 1.7 Jul 11 9.9 HH Jul 11 16.8 LL Jul 11 9.5 HH Jul 11 16.0 LL 0.4 0.8 5.153 3.622 3.365 1.900 1.7 Jul 12 0.1 H Jul 12 5.5 L Jul 11 23.7 H Jul 12 4.9 L 0.4 0.6 5.110 4.359 3.325 2.651 1.7 Jul 12 10.8 H Jul 12 17.2 LL Jul 12 10.4 H Jul 12 16.5 LL 0.4 0.7 4.992 3.705 3.211 1.998 1.7 Jul 13 0.6 HH Jul 13 6.3 L Jul 13 0.1 HH Jul 13 5.8 L 0.5 0.5 5.155 4.294 3.362 2.565 1.7 Jul 13 11.7 H Jul 13 17.8 LL Jul 13 11.3 H Jul 13 17.1 LL 0.4 0.7 4.875 3.899 3.090 2.204 1.7  HHW HLW HHW HLW H SUMS 152.709 122.201 102.699 74.045 50.0 ITEMS 28 28 28 28 28  MEANS 5.454 4.364 3.668 2.644 1.7 STD DEV 0.0  LHW LLW LHW LLW L SUMS 25.60 36.50 138.919 97.465 88.944 48.861 49.9 ITEMS 56 56 28 28 28 28 28  MEANS 0.46 0.65 4.961 3.481 3.177 1.745 1.7 STD DEV 0.11 0.13 0.0  Figure 1.6. Tide-By-Tide Comparison (continued)                
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 26

Begin: Jun 15 2005 00:00 COMPARISON OF SIMULTANEOUS OBSERVATIONS Tidal Epoch: 

 End: Jul 14 2005 00:00 Expected Dif Run: Jan 31 2007 16:30 * Exceeds 2   (A) Subordinate Station: 9414863 RICHMOND, CHEVRON OIL PIER Verified T.M.: 0W Tide Type: 

(B) Standard Station: 9414290 SAN FRANCISCO, SAN FRANCISCO BAY Verified T.M.: 0W Tide Type: 

   Mean Difference in HWI: 0.46 Mean Difference in LWI: 0.65  Mean HHW Height at (A): 5.454 Mean HLW Height at (A): 4.364 Mean LHW Height at (A): 4.961 Mean LLW Height at (A): 3.481 DHQ at (A): 0.246 DLQ at (A): 0.442  Mean HW Height at (A): 5.208 Mean LW Height at (A): 3.923 MN at (A): 1.285 MTL at (A): 4.565  GT at (A): 1.973 DTL at (A): 4.467   Mean HHW Difference: 1.786 Mean HLW Difference: 1.720  Mean LHW Difference: 1.785 Mean LLW Difference: 1.736  DHQ Difference: 0.001 DLQ Difference: -0.008  Mean HW Difference: 1.785 Mean LW Difference: 1.728  MN Difference: 0.058 MTL Difference: 1.757  GT Difference: 0.050 DTL Difference: 1.761  MN Ratio: 1.047 DHQ Ratio: 1.003  GT Ratio: 1.026 DLQ Ratio: 0.982  MSL (100.00%) at (A): 4.548  MSL (100.00%) at (B): 2.782  MSL Difference: 1.766   HWI LWI MTL MN MSL DHQ DLQ  Hours Hours Meters Meters Meters Meters Meters  Accepted for B: 7.53 0.85 2.792 1.248 2.773 0.186 0.346  Differences and Ratios: 0.46 0.65 1.757 1.047 1.766 1.003 0.982  Corrected for A: 7.99 1.50 4.549 1.307 4.539 0.186 0.340    FINAL/PRELIMINARY DATUMS Standard Method   MHHW ---|--- 5.388 | DHQ 0.186 MHW -|- 5.202 | DTL -|- 4.472 | GT 1.833 MTL -|- 4.549 | MN 1.307 MSL -|- 4.539 | MLW -|- 3.895 Date 

| DLQ 0.340 MLLW ---|--- 3.555 HWI: 7.99 Comparison _____

 

 On Staff Of: LWI: 1.50 Verified _____

Figure 1.6. Tide-By-Tide Comparison (concluded) 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 27

 COMPARISON OF MONTHLY MEANS (Jan 2005 - Dec 2005) Feb 01, 2007  1983-2001 TIDAL EPOCH  (A) SUBORDINATE STATION 9414863 RICHMOND, CHEVRON OIL PIER Product TM (0W) TIDE TYPE (M) (B) STANDARD STATION 9414290 SAN FRANCISCO, SAN FRANCISCO BAY Product TM (0W) TIDE TYPE (M)   Mon Year M T L M S L H W I L W I M N  A B A - B A B A - B A B A - B A B A - B A B A / B  METER METER METER METER METER METER HRS HRS HRS HRS HRS HRS METER METER RATIO Jan 2005 4.665 2.900 1.765 4.650 2.876 1.774 7.890 7.450 0.440 1.380 0.750 0.630 1.293 1.212 1.067 Feb 2005 4.639 2.875 1.764 4.626 2.853 1.773 7.970 7.520 0.450 1.430 0.800 0.630 1.315 1.239 1.061 Mar 2005 4.593 2.813 1.780 4.575 2.791 1.784 7.890 7.450 0.440 1.320 0.690 0.630 1.288 1.207 1.067 Apr 2005 4.503 2.740 1.763 4.485 2.713 1.772 7.890 7.500 0.390 1.380 0.720 0.660 1.276 1.199 1.064 May 2005 4.563 2.805 1.758 4.542 2.773 1.769 7.890 7.480 0.410 1.430 0.720 0.710 1.281 1.209 1.060 Jun 2005 4.535 2.780 1.755 4.517 2.750 1.767 7.870 7.450 0.420 1.430 0.710 0.720 1.274 1.210 1.053 Jul 2005 4.607 2.856 1.751 4.590 2.826 1.764 7.950 7.490 0.460 1.460 0.840 0.620 1.284 1.231 1.043 Aug 2005 4.604 2.864 1.740 4.593 2.838 1.755 7.970 7.520 0.450 1.490 0.880 0.610 1.279 1.230 1.040 Sep 2005 4.571 2.838 1.733 4.565 2.819 1.746 7.880 7.460 0.420 1.420 0.830 0.590 1.273 1.225 1.039 Oct 2005 2.809 2.787 7.420 0.810 1.235 Nov 2005 2.781 2.751 7.440 0.830 1.229 Dec 2005 2.840 2.805 7.460 0.800 1.245   Mon Year D H Q D L Q M H W M L W  A B A / B A B A / B A B A - B A B A - B  METER METER RATIO METER METER RATIO METER METER METER METER METER METER Jan 2005 0.227 0.224 1.013 0.401 0.406 0.988 5.312 3.506 1.806 4.019 2.294 1.725 Feb 2005 0.207 0.204 1.015 0.350 0.354 0.989 5.296 3.494 1.802 3.981 2.255 1.726 Mar 2005 0.154 0.152 1.013 0.329 0.324 1.015 5.237 3.417 1.820 3.949 2.210 1.739 Apr 2005 0.156 0.156 1.000 0.388 0.380 1.021 5.141 3.339 1.802 3.865 2.140 1.725 May 2005 0.179 0.179 1.000 0.431 0.427 1.009 5.204 3.409 1.795 3.923 2.200 1.723 Jun 2005 0.246 0.245 1.004 0.439 0.439 1.000 5.172 3.385 1.787 3.898 2.175 1.723 Jul 2005 0.258 0.257 1.004 0.429 0.441 0.973 5.249 3.471 1.778 3.965 2.240 1.725 Aug 2005 0.218 0.216 1.009 0.376 0.393 0.957 5.244 3.479 1.765 3.965 2.249 1.716 Sep 2005 0.161 0.156 1.032 0.305 0.324 0.941 5.207 3.451 1.756 3.934 2.226 1.708 Oct 2005 0.140 0.324 3.427 2.192 Nov 2005 0.204 0.417 3.395 2.166 Dec 2005 0.256 0.487 3.462 2.217  Mon Year D R L(TL) G T M H H W M L L W  A B A - B A B A / B A B A - B A B A - B  METER METER RATIO METER METER RATIO METER METER METER METER METER METER Jan 2005 4.579 2.809 1.770 1.921 1.842 1.043 5.539 3.730 1.809 3.618 1.888 1.730 Feb 2005 4.567 2.800 1.767 1.872 1.797 1.042 5.503 3.698 1.805 3.631 1.901 1.730 Mar 2005 4.505 2.728 1.777 1.771 1.683 1.052 5.391 3.569 1.822 3.620 1.886 1.734 Apr 2005 4.387 2.628 1.759 1.820 1.735 1.049 5.297 3.495 1.802 3.477 1.760 1.717 May 2005 4.438 2.680 1.758 1.891 1.815 1.042 5.383 3.588 1.795 3.492 1.773 1.719 Jun 2005 4.439 2.683 1.756 1.959 1.894 1.034 5.418 3.630 1.788 3.459 1.736 1.723 Jul 2005 4.521 2.764 1.757 1.971 1.929 1.022 5.507 3.728 1.779 3.536 1.799 1.737 Aug 2005 4.526 2.776 1.750 1.873 1.839 1.018 5.462 3.695 1.767 3.589 1.856 1.733 Sep 2005 4.498 2.755 1.743 1.739 1.705 1.020 5.368 3.607 1.761 3.629 1.902 1.727 Oct 2005 2.718 1.699 3.567 1.868 Nov 2005 2.674 1.850 3.599 1.749 Dec 2005 2.724 1.988 3.718 1.730 Figure 1.7. Monthly Mean Simultaneous Comparison Example 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 28

COMPARISON OF MONTHLY MEANS (Jan 2005 - Dec 2005) Fe

1983-2001 TIDAL EPOCH 

 (A) SUBORDINATE STATION 9414863 RICHMOND, CHEVRON OIL PIER Product TM (0W) TIDE TYPE (M) (B) STANDARD STATION 9414290 SAN FRANCISCO, SAN FRANCISCO BAY Product TM (0W) TIDE TYPE (M)    M T L M S L H W I L W I M N  A - B A - B A - B A - B A / B  METER METER HRS HRS RATIO TOTAL MONTHS 9.000 9.000 9.000 9.000 9.000 SUMS 15.809 15.904 3.880 5.800 9.494 MEANS 1.757 1.767 0.431 0.644 1.055 ACCEPTED FOR B 2.792 2.773 7.535 0.848 1.248 CORRECTED FOR A 4.549 4.540 7.966 1.492 1.317    D H Q D L Q M H W M L W  A / B A / B A - B A - B  RATIO RATIO METER METER TOTAL MONTHS 9.000 9.000 9.000 9.000 SUMS 9.090 8.893 16.111 15.510 MEANS 1.010 0.988 1.790 1.723 ACCEPTED FOR B 0.186 0.346 3.416 2.168 CORRECTED FOR A 0.188 0.342 5.206 3.891    D R L(TL) G T M H H W M L L W  A - B A / B A - B A - B  METER RATIO METER METER TOTAL MONTHS 9.000 9.000 9.000 9.000 SUMS 15.837 9.322 16.128 15.550 MEANS 1.760 1.036 1.792 1.728 ACCEPTED FOR B 2.712 1.780 3.602 1.822 CORRECTED FOR A 4.472 1.844 5.394 3.550    METHOD DATUM VALUE FINAL/PRELIMINARY DATUMS  MODIFIED RANGE RATIO MHHW = 5.394 MHHW ---|--- 5.395 MODIFIED RANGE RATIO MLLW = 3.550 | DHQ 1.88 MODIFIED RANGE RATIO DHQ = 0.187 MHW -|- 5.207 MODIFIED RANGE RATIO DLQ = 0.340 | MTL -|- 4.549 STANDARD MHW = 5.207 | GT 1.846 STANDARD MLW = 3.890 DTL -|- 4.472 STANDARD MHHW = 5.395 | MN 1.317 STANDARD MLLW = 3.548 MSL -|- 4.540 | DIRECT MN = 1.315 MLW -|- 3.890 DIRECT GT = 1.844 | DLQ 0.342 DIRECT DHQ = 0.188 MLLW ---|--- 3.548 DIRECT DLQ = 0.342  ON STAFF OF:  TABULATED __________________________  VERIFIED __________________________ 

Figure 1.7. Monthly Mean Simultaneous Comparison (continued) 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 29

COMPARISON OF MONTHLY MEANS (Jan 2005 - Dec 2005) Feb 01, 200

 1983-2001 TIDAL EPOCH  (A) SUBORDINATE STATION 9414863 RICHMOND, CHEVRON OIL PIER Product TM (0W) TIDE TYPE (M) (B) STANDARD STATION 9414290 SAN FRANCISCO, SAN FRANCISCO BAY Product TM (0W) TIDE TYPE (M)    O U T L I E R R E P O R T   (MEAN DIFFERENCE EXCEEDS 2 STD. DEV. (MAX/MIN))   M T L M S L H W I L W I M N D H Q D L Q M H W M L W D T L G T M H H W M L L W Std.Dev. 0.009 0.007 0.014 0.034 0.007 0.008 0.016 0.013 0.005 0.007 0.008 0.013 0.004 Std.Dev. 

MAX 1.774 1.780 0.459 0.712 1.069 1.025 1.021 1.816 1.734 1.774 1.052 1.818 1.736 MAX MIN 1.739 1.754 0.404 0.577 1.041 0.995 0.956 1.765 1.713 1.745 1.020 1.766 1.719 MIN MON YEAR Jan 2005 Jan 2005 Feb 2005 Feb 2005 Mar 2005 1.780 1.784 1.820 1.739 1.777 1.052 1.822 Mar 2005 Apr 2005 0.390 1.021 1.717 Apr 2005 May 2005 1.719 May 2005 Jun 2005 0.720 Jun 2005 Jul 2005 0.460 1.737 Jul 2005 Aug 2005 1.040 1.018 Aug 2005 Sep 2005 1.733 1.746 1.039 1.032 0.941 1.756 1.708 1.743 1.761 Sep 2005 Oct 2005 Oct 2005 Nov 2005 Nov 2005 Dec 2005 Dec 2005

Figure 1.7. Monthly Mean Simultaneous Comparison (concluded) 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 30

 

U.S. DEPARTMENT OF COMMERCE 

 National Oceanic and Atmospheric Administration 

 National Ocean Service 

 Page 1 of 8 

 

Station ID: 9414290 PUBLICATION DATE: 04/21/2003 

Name: SAN FRANCISCO 

 CALIFORNIA 

NOAA Chart: 18649 Latitude: 37° 48.4' N 

USGS Quad: SAN FRANCISCO NORTH Longitude: 122° 27.9' W 

To reach the tidal bench marks, proceed west along U.S. Highway 101 in the 

direction of the Golden Gate Bridge, then NW along Crissey Field Avenue (before 

the bridge) to the Golden Gate National Park (Presidio). The bench marks are 

located mostly along the coast in the vicinity. The tide gauge is located on 

the NE side of the National Parks Service wharf. 

 T I D A L B E N C H M A R K S 

 PRIMARY BENCH MARK STAMPING: 180 1936 

 DESIGNATION: 941 4290 TIDAL 180 

MONUMENTATION: Tidal Station disk VM#: 967 

AGENCY: US Coast and Geodetic Survey (USC&GS) PID: HT0702 

SETTING CLASSIFICATION: Concrete sea wall 

The primary bench mark is a disk set in the top of a 1 m (3 ft) high concrete 

seawall in Golden Gate National Park at the Gulf of Farallons National Marine 

Sanctuary headquarters, 15 m (50 ft) east of the NE corner of the Sanctuaries 

building, 6.10 m (20.0 ft) south of the south side of the garage building, and 

1.07 m (3.5 ft) north of an angle in wall. 

 BENCH MARK STAMPING: BM 174 1925 

 DESIGNATION: 941 4290 TIDAL 174 

 ALIAS: TIDAL 174 

MONUMENTATION: Tidal Station disk VM#: 971 

AGENCY: US Coast and Geodetic Survey (USC&GS) PID: HT0697 

SETTING CLASSIFICATION: Concrete monument 

The bench mark is a disk set in a concrete post flush with the ground inside a 

circle of bricks in the pavement, 38.10 m (125.0 ft) west of the extended west 

edge of Engineer's Dock where it crosses Marine Drive, at the center of "Y" 

between Marine Drive and the road leading SE to Fort Winfield Scott, 12.95 m 

(42.5 ft) SW of the fire hydrant, and 8.69 m (28.5 ft) south of the south edge 

of an iron manhole cover. 

Figure 1.8. Published Bench Mark Sheet
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 31

 

U.S. DEPARTMENT OF COMMERCE 

 National Oceanic and Atmospheric Administration 

 National Ocean Service 

 Page 2 of 8 

 

Station ID: 9414290 PUBLICATION DATE: 04/21/2003 

Name: SAN FRANCISCO 

 CALIFORNIA 

NOAA Chart: 18649 Latitude: 37° 48.4' N 

USGS Quad: SAN FRANCISCO NORTH Longitude: 122° 27.9' W 

 T I D A L B E N C H M A R K S 

 BENCH MARK STAMPING: BM 176 1925 

 DESIGNATION: 941 4290 TIDAL 176 

 ALIAS: TIDAL 176 

MONUMENTATION: Tidal Station disk VM#: 972 

AGENCY: US Coast and Geodetic Survey (USC&GS) PID: HT0705 

SETTING CLASSIFICATION: Concrete step 

The bench mark is a disk set in the west end of the lowest concrete step at the 

main entrance to the porch of the building at No. 651 Mason Street, 29.87 m 

(98.0 ft) SE of the intersection of Crissey Field Avenue and Mason Street, 15.24 

m (50.0 ft) south of the centerline of Mason Street, and 0.21 m (0.7 ft) above 

sidewalk. 

 BENCH MARK STAMPING: 181 1945 

 DESIGNATION: 941 4290 TIDAL 181 

 ALIAS: TIDAL 181 

MONUMENTATION: Tidal Station disk VM#: 973 

AGENCY: US Coast and Geodetic Survey (USC&GS) PID: HT0701 

SETTING CLASSIFICATION: Sea wall 

The bench mark is a disk set in NW corner of a sea wall at the Golden Gate 

National Park at the Gulf of Farallons National Marine Sanctuary headquarters, 

62 m (204 ft) west of the inshore end of the pier, 45.87 m (150.5 ft) NW of a 

flag pole, 21.64 m (71.0 ft) NE of the north corner of Building S.F. 19.4 (paint 

shop and storage building), and 1.22 m (4.0 ft) above ground. 

Figure 1.8 Published Bench Mark Sheet (continued) 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 32

 

 U.S. DEPARTMENT OF COMMERCE 

 National Oceanic and Atmospheric Administration 

 National Ocean Service 

 Page 3 of 8 

 

Station ID: 9414290 PUBLICATION DATE: 04/21/2003 

Name: SAN FRANCISCO 

 CALIFORNIA 

NOAA Chart: 18649 Latitude: 37° 48.4' N 

USGS Quad: SAN FRANCISCO NORTH Longitude: 122° 27.9' W 

 T I D A L B E N C H M A R K S 

 BENCH MARK STAMPING: NO 2 1948 

 DESIGNATION: CLARK RM 2 

 ALIAS: 941 4290 TIDAL 183 

MONUMENTATION: Triangulation Station disk VM#: 975 

AGENCY: US Coast and Geodetic Survey (USC&GS) PID: HT0700 

SETTING CLASSIFICATION: Sea wall 

The bench mark is a disk set flush in the top of a sea wall west of the public 

fishing pier, 11.43 m (37.5 ft) west of the west edge of the pier, 8.08 m (26.5 

ft) NE of the NE corner of corrugated iron building No. 985, and about 0.91 m 

(3.0 ft) above ground. 

 BENCH MARK STAMPING: CLARK 1948 

 DESIGNATION: CLARK 

 ALIAS: 941 4290 TIDAL 185 

MONUMENTATION: Triangulation Station disk VM#: 976 

AGENCY: US Coast and Geodetic Survey (USC&GS) PID: HT0698 

SETTING CLASSIFICATION: Concrete sea wall 

The bench mark is a disk set in the top of a concrete sea wall west of the 

public fishing pier, about 549 m (1800 ft) NW of the Gulf of Farallons National 

Marine Sanctuary headquarters in Golden Gate National Park, 24.23 m (79.5 ft) 

west of the west edge of the pier, 6.86 m (22.5 ft) NE of the NW corner of 

corrugated iron building No. 985, 3.05 m (10.0 ft) west of the NW corner of a 

stucco paint locker building, and 1.07 m (3.5 ft) above ground. 

Figure 1.8: Published Bench Mark Sheet (continued) 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 33

 

 U.S. DEPARTMENT OF COMMERCE 

 National Oceanic and Atmospheric Administration 

 National Ocean Service 

 Page 4 of 8 

 

Station ID: 9414290 PUBLICATION DATE: 04/21/2003 

Name: SAN FRANCISCO 

 CALIFORNIA 

NOAA Chart: 18649 Latitude: 37° 48.4' N 

USGS Quad: SAN FRANCISCO NORTH Longitude: 122° 27.9' W 

 T I D A L B E N C H M A R K S 

 BENCH MARK STAMPING: 4290 K 1976 

 DESIGNATION: 941 4290 K TIDAL 

MONUMENTATION: Tidal Station disk VM#: 978 

AGENCY: National Ocean Service (NOS) PID: HT2255 

SETTING CLASSIFICATION: Bedrock 

The bench mark is a disk set vertically in bedrock on the south side of Marine 

Drive, 24 m (79 ft) SSW of the SE corner of the National Park Service building # 

T989, 14.69 m (48.2 ft) NW of bench mark BM 174 1925, and 2.44 m (8.0 ft) south 

of the road curb. 

 BENCH MARK STAMPING: 4290 L 1976 

 DESIGNATION: 941 4290 L TIDAL 

MONUMENTATION: Tidal Station disk VM#: 979 

AGENCY: National Ocean Survey (NOS) PID: HT2253 

SETTING CLASSIFICATION: Bedrock 

The bench mark is a disk set in bedrock on the south side of Marine Drive, 114 m 

(375 ft) west of the National Park Service building # T989, 15.70 m (51.5 ft) SE 

of the eastern-most concrete and steel safety chain stanchion on the seawall, 

7.77 m (25.5 ft) from the centerline of Marine Drive, and 1.22 m (4 ft) above 

street level. 

Figure 1.8: Published Bench Mark Sheet (continued) 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 34

 

 U.S. DEPARTMENT OF COMMERCE 

 National Oceanic and Atmospheric Administration 

 National Ocean Service 

 Page 5 of 8 

 

Station ID: 9414290 PUBLICATION DATE: 04/21/2003 

Name: SAN FRANCISCO 

 CALIFORNIA 

NOAA Chart: 18649 Latitude: 37° 48.4' N 

USGS Quad: SAN FRANCISCO NORTH Longitude: 122° 27.9' W 

 T I D A L B E N C H M A R K S 

 BENCH MARK STAMPING: 4290 M 1982 

 DESIGNATION: 941 4290 M TIDAL 

MONUMENTATION: Tidal Station disk VM#: 980 

AGENCY: National Ocean Survey (NOS) PID: HT3538 

SETTING CLASSIFICATION: Concrete foundation 

The bench mark is a disk set flush in concrete foundation in front of Stilwell 

Hall (building # 650) on Mason Street, 27.34 m (89.7 ft) south of the centerline 

of Mason street, 10.30 m (33.8 ft) east of the NE corner of the west wing of the 

Stilwell Hall, 6.07 m (19.9 ft) west of the west edge of the sidewalk leading to 

the entrance of Stilwell Hall, 0.30 m (1.0 ft) SE of the NW corner of the 

foundation, and 0.12 m (0.4 ft) above ground level. 

 BENCH MARK STAMPING: BM 175 1925 

 DESIGNATION: 941 4290 TIDAL 175 

 ALIAS: TIDAL 175 

MONUMENTATION: Tidal Station disk VM#: 1829 

AGENCY: US Coast and Geodetic Survey (USC&GS) PID: HT0696 

SETTING CLASSIFICATION: Sea wall 

The bench mark is a disk set in top surface of the sea wall, near the National 

Park Service building at the intersection of the pavement and the seawall, 65.23 

m (214.0 ft) NE of bench mark 4290 L 1976, 58.67 m (192.5 ft) west from the NW 

corner of the National Park Service building, 28.90 m (94.8 ft) WNW of the 

northern-most post of pedestrian gate, 6.86 m (22.5 ft) north of the centerline 

of Marine Drive, and 0.73 m (2.4 ft) south from the north edge of the sea wall. 

Figure 1.8: Published Bench Mark Sheet (continued) 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 35

 

 U.S. DEPARTMENT OF COMMERCE 

 National Oceanic and Atmospheric Administration 

 National Ocean Service 

 Page 6 of 8 

 

Station ID: 9414290 PUBLICATION DATE: 04/21/2003 

Name: SAN FRANCISCO 

 CALIFORNIA 

NOAA Chart: 18649 Latitude: 37° 48.4' N 

USGS Quad: SAN FRANCISCO NORTH Longitude: 122° 27.9' W 

 T I D A L B E N C H M A R K S 

 BENCH MARK STAMPING: 4290 N 1995 

 DESIGNATION: 941 4290 N 

MONUMENTATION: Tidal Station disk VM#: 15436 

AGENCY: National Ocean Service (NOS) PID: AE5209 

SETTING CLASSIFICATION: Concrete sea wall 

The bench mark is a disk set in a concrete seawall in Golden Gate National Park 

at the Gulf of Farallons National Marine Sanctuary headquarters, near an inshore 

end of a walkway leading to a pier, 13.70 m (44.9 ft) north of bottom of stairs 

leading to the Sanctuary building, 3.96 m (13.0 ft) east of a step in seawall, 

and 3.20 m (10.5 ft) west of the center of the walkway. 

Figure 1.8: Published Bench Mark Sheet (continued) 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 36

 

 U.S. DEPARTMENT OF COMMERCE 

 National Oceanic and Atmospheric Administration 

 National Ocean Service 

 Page 7 of 8 

 

Station ID: 9414290 PUBLICATION DATE: 04/21/2003 

Name: SAN FRANCISCO 

 CALIFORNIA 

NOAA Chart: 18649 Latitude: 37° 48.4' N 

USGS Quad: SAN FRANCISCO NORTH Longitude: 122° 27.9' W 

 T I D A L D A T U M S 

Tidal datums at SAN FRANCISCO based on: 

 LENGTH OF SERIES: 19 Years 

 TIME PERIOD: January 1983 - December 2001 

 TIDAL EPOCH: 1983-2001 

 CONTROL TIDE STATION: 

Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: 

 HIGHEST OBSERVED WATER LEVEL (01/27/1983) = 2.640 

 MEAN HIGHER HIGH WATER (MHHW) = 1.780 

 MEAN HIGH WATER (MHW) = 1.595 

 MEAN TIDE LEVEL (MTL) = 0.970 

 MEAN SEA LEVEL (MSL) = 0.951 

 MEAN LOW WATER (MLW) = 0.346 

 MEAN LOWER LOW WATER (MLLW) = 0.000 

 NORTH AMERICAN VERTICAL DATUM-1988 (NAVD) = -0.018 

 LOWEST OBSERVED WATER LEVEL (12/17/1933) = -0.877 

Bench Mark Elevation Information In METERS above: 

 Stamping or Designation MLLW MHW 

 180 1936 3.972 2.378 

 BM 174 1925 5.013 3.418 

 BM 176 1925 4.814 3.219 

 181 1945 3.987 2.392 

 NO 2 1948 4.221 2.626 

 CLARK 1948 4.233 2.639 

 4290 K 1976 5.828 4.234 

 4290 L 1976 6.620 5.025 

 4290 M 1982 3.705 2.111 

 BM 175 1925 4.160 2.566 

 4290 N 1995 3.646 2.051 

Figure 1.8: Published Bench Mark Sheet (continued) 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 37

 

 U.S. DEPARTMENT OF COMMERCE 

 National Oceanic and Atmospheric Administration 

 National Ocean Service 

 Page 8 of 8 

 

Station ID: 9414290 PUBLICATION DATE: 04/21/2003 

Name: SAN FRANCISCO 

 CALIFORNIA 

NOAA Chart: 18649 Latitude: 37° 48.4' N 

USGS Quad: SAN FRANCISCO NORTH Longitude: 122° 27.9' 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 (NAVD 88). 

NGVD 29 is a fixed datum adopted as a national standard geodetic reference for 

heights but is now considered superseded. NGVD 29 is sometimes referred to as 

Sea Level Datum of 1929 or as Mean Sea Level on some early issues of Geological 

Survey Topographic Quads. NGVD 29 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 NGVD 29 are available from the National 

Geodetic Survey (NGS) data base via the World Wide Web at 

http://www.ngs.noaa.gov/cgi-bin/ngs_opsd.prl?PID=HT0702&EPOCH=1983-2001. 

NAVD 88 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. NAVD 88 replaces NGVD 29 as the national 

standard geodetic reference for heights. Bench mark elevations relative to 

NAVD 88 are available from NGS through the World Wide Web at 

http://www.ngs.noaa.gov/cgi-bin/ngs_opsd.prl?PID=HT0702&EPOCH=1983-2001. 

NGVD 29 and NAVD 88 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 NAVD 88 elevation is shown on the Elevations of Tidal Datums Table Referred 

to MLLW only when two or more of the bench marks listed have NAVD 88 elevations. 

The NAVD 88 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, NAVD 88 bench mark elevations computed indirectly from the tidal 

datums elevation table may differ slightly from NAVD 88 elevations listed for 

each bench mark in the NGS database. 

Figure 1.8: Published Bench Mark Sheet (concluded)
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 38

 

1.5 Data Submission Requirements 

Data submission requirements for water level measurement stations are comprised of timely 

submissions of both documentation and data, which involve (a) supporting documents for the 

installation, maintenance, and removal of stations, (b) the formatted digital water level data 

collected by the water level measurement system required for the quality control and ingestion 

into the CO-OPS data base management system, and (c) documentation for processing and 

tabulation of the data, and tidal datum computation are required. 

Data submission requirements for GPS are listed as specified in CO-OPS “User’s Guide for GPS 

Observations At Tide and Water Level Station Bench Marks”. 

(http://tidesandcurrents.noaa.gov/publications/Users_Guide_for_GPS_Observations_updated_No

vember_2008.pdf ) 

1.5.1 Station Documentation 

The documentation package shall be forwarded after (a) installation of a station, (b) performance 

of bracketing levels, (c) gauge maintenance and repair, or (d) removal of the station. Refer to 

Section 1.5.3 for required documentation details and time lines for submission requirements, and 

Figure 1.9, Water Level Station Documentation Check-off List provides additional details. 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 39

 

For Each Water Level Station: 

PROJECT DOCUMENTATION AND DATA CHECK-OFF LIST 

Project Number: Locality: 

Station Number: Station Name: 

A. Transmittal Letter 

 1. Transmittal letter attached with current contractor address, phone number and email. 

B. Site Report (required for both installation and removal)

1. All applicable information complete, especially serial numbers of DCP/sensors and 

dates of installation/removal of DCP/sensors and levels 

 2. Verify latitude and longitude of the station (ensure that this is the same as on the 

field tide note for Hydro/Photo surveys). Provide latitude and longitude in d/m/s.x 

format as determined by handheld GPS for the primary sensor. 

 3. Note UTC time and date the datum offset and sensor offset entered or changed in the 

DCP 

4. Provide metadata for ancillary sensors, if installed and as required 

5. Provide notes on results of diving inspection, and cleaning of underwater 

components. 

6. Provide status of valid tie to NAVD 88 geodetic marks, if applicable, in level section 

remarks area. 

7. Provide notes of excessive movement of water level sensor or bench marks in level 

section remarks area. 

C. NOAA Chart Section 

 1. Ensure that station location is clearly depicted with circle and station number. 

 2. Standard title block includes station number, station name, lat/long as d/m/s.x,, 

NOAA chart number, edition, date, and scale, USGS quad name all in caps. 

 3. Provide a digital copy of the chart section in jpg format 

D. Bench Mark/Station Location Sketch

 1. Ensure gauge, staff and bench marks are shown, and local body of water is labeled. 

 2. Ensure Standard Title block includes: station number and station name, field unit, 

date of revision 

 3. Ensure North arrow depicted. 

 4. Include in digital format. 

 5. Ensure all active (recovered and not recovered) bench marks are identified by 

designations 

 6. Ensure bench marks that are confirmed as destroyed are removed from the sketch. 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 40

 

 7. Provide a digital copy of the sketch saved in jpg format. 

E. Digital Photographs

 1. Provide digital photographs of gauge, staff, surrounding area, wells and brackets, 

DCP. Provide tide gauge photos from two perpendicular directions. 

 2. Station component file name starts with station number followed by the specific 

component view, with jpg extension (e.g. 86610170 well.jpg ) 

 3. Provide several shots of met towers and sensors from different directions (e.g. 

8661070 met tower looking east.jpg) 

 4. Provide digital photos of bench mark – 4 photos required as follows - close up of 

disk without GPS handheld in view, eye-level view looking down, and two photos 

looking horizontally from different directions (90 degrees apart, if possible) 

showing general location for all new marks. Follow bench mark photo file naming 

convention as specified by NGS. 

F. Bench Mark Descriptions/Recovery Notes

 1. Stampings for new and recovered marks verified in all documents. 

 2. Descriptions for new marks provided in CO-OPS format (MS Word). 

 3. Recovery notes provided for all historical marks. Recovered As Described (RAD) 

RAD/xxx noted for all recovered marks, where xxx is party chief, or contractor 

initial. 

 4. Provide handheld GPS position in d/m/s.x format at the end of the text description. 

 5. For electronic levels, make sure HA files codes are completed accurately 

 6. For electronic levels, text description begins with a statement on how to reach the 

mark, followed by the description in CO-OPS format 

 7. For electronic levels, provide handheld GPS position in d/m/s format at the end of 

the text in HA file since HA file does not accept decimal seconds s.x 

G. Levels

 1. Ensure all information written in ink. 

 2. Station name, number, level instrument type model and serial number, rods type 

model and serial numbers, date, personnel. 

 3. Note type of levels - installation, bracketing and closing. 

 4. Staff information complete (if applicable). 

 5. Collimation check shown. 

 6. Note that bench mark descriptions are submitted for all installed and recovered 

marks as a MS Word file. 

 7. Headers on all applicable pages complete. 

 8. For multi year projects, all marks must be connected every two years. 

 9. Levels include marks specially noted in station specific requirements of the project 

instructions. 

 10. Explanation provided for any marks not leveled during this level run. 

 11. Provide sectional and overall closure tolerances and ascertain they are within 

allowable limits. 

 12. Compute level abstract starting with PBM accepted elevation and ending with 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 41

 

primary sensor elevation 

 13. Check for valid leveling tie to NAVD 88 if required and made. 

 14. For electronic levels, provide original IN file in separate folder if modified IN file 

is provided. 

 15. For electronic levels, all file dates must be chronologically consistent, i.e. the HA 

and INX files can not have dates more recent than the ABS file 

 16. For electronic levels, provide Invar rod calibration certificates for the first time 

digital leveling. For optical levels provide rod calibration certificates. 

 17. For electronic levels, error flags are not allowed on sectional distances of the ABS 

file 

H. Datum Offset Computation Worksheet

 1. Submit for stations that have Vitel or Sutron DCP with Aquatrak sensor. 

I. Data Submitted in electronic media (CD-ROM/DVD/FTP site)

 1. Label electronic media with contractor name and list of files on each media. 

 2. 6-minute Data files should be named in the following format: xxxxxxxy.w1.dat, 

where xxxxxxx = seven digit station number and y is the DCP # and w1 is the 

product code. For multiple files from the same station, change the extension, i.e., 

xxxxxxx1.w1.da1, da2, etc. Similarly name hourly heights data file as 

xxxxxxx.w2.dat; high and low data files as xxxxxxx.w3.dat; monthly means data 

file as xxxxxxx.w5.dat; and station datum data file as xxxxxxx.w7.dat 

3. Check the begin and end dates of data submitted with dates of shoreline mapping 

operations, or project duration for special projects. 

 4. Check data continuity. 

J. Transmittal Letter

 1. Transmittal letter attached with current contractor address, phone number and email. 

K. All Documentation Enclosed in Tide Level Envelope (NOAA Form 75-29A)

 1. Leave “sheets” box blank, complete other information in title boxes. 

 2. Verified completed with signature by contractor and include date. 

Figure 1.9. Project Documentation and Data Check-off List 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 42

 

1.5.2 Water Level Data 

The final observed water level measurements shall be reported as heights in meters to three 

decimal places (i.e. 0.001 m). All heights shall be referenced to station datum and shall be 

referenced to UTC or GMT. The contractor shall provide the water level data in the format 

specified below from the water level gauges installed. 

The original raw water level data and the correctors used to convert the data to chart datum shall 

be retained until notified in writing or at least three years after the survey is completed. All 

algorithms and conversions used to provide correctors shall be fully supported by the 

calibrations, maintenance documentation, leveling records, and sound engineering/oceanographic 

practices. Factors used to convert the measured data (e.g. pressure to water level heights) shall be 

maintained for the entire water level collection period and reported. 

All digital water level and ancillary data shall be transmitted to CO-OPS in a format dependent 

on the DCP configuration. If GOES satellite is used for NOAA in-house surveys, the data shall 

be transmitted and received using the NOS compressed pseudo binary format (see NGWLMS 

GOES Message Formatting, Libraro, January 2003 at the following url: 

http://tidesandcurrents.noaa.gov/publications/newgoes_format.pdf ). These satellite messages are 

then decoded by NOS DMS upon receipt from NESDIS before further processing and review by 

CORMS can be completed. If satellite transmission configurations cannot be installed, the data 

shall be manually downloaded from the DCP and submitted to NGS, as shown in the format 

below, in a digital format, on CD-ROM, or by email as an ASCII data attachment. 

Six-minute water level data download files shall be named in the following format: 

xxxxxxxy.w1.dat, where xxxxxxx is the seven digit station number, y is the DCP number 

(usually 1), w1 is the product code for 6-minute data, and dat is the extension (Use t = 2,3...if 

more than one file is from the same station and DCP). This is the format needed when the data is 

loaded into DMS. 

Multiple DCP may have been used to collect 6-minute water level data for a particular site, and 

backup or redundant DCP data may be used to fill the gap in the primary DCP data, but, water 

level data shall be submitted for a single DCP (numbered as 1). When data from more than one 

DCP is used to fill the gap, care should be taken to apply the proper correctors (such as gain and 

offsets, or appropriate staff constants for each DCP/sensor) so that all the 6-minute water level 

data and the processed products such as hourly heights, high and low data, monthly means data, 

and station shall be placed on the station datum. 

Each input record (including the final record) ends with a carriage return and excludes any 

extraneous characters such as trailing blank spaces for all types of water level data (6-minute 

water level data, hourly height, high/low, monthly means, and station datum). 

The 6-minute interval data (acoustic sensor and pressure sensor examples follow) shall have the 

following format for CO-OPS database to accept. 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 43

 

1.5.2.1 Acoustic Sensor Data (XXX.ACO format) 

Column 1- 7 Station ID (7 digits, assigned in the project instructions) 

Column 8- 8 1 (DCP number, use 2, 3 , etc., for additional DCPs) 

Column 9-19 Date (MMM DD YYYY format, e.g. JAN 01 1998) 

Column 20-20 Blank 

Column 21-22 Hours in 24 hour format (i.e. 00, 01, ...., 23) 

Column 23-23 : (colon) 

Column 24-25 Minutes (00,06,12, ..., 54) 

Column 26-32 Data value in millimeters, right justified, (e.g. 1138) 

Column 33-38 Sigma (standard deviation in millimeters in integer format) 

Column 39-44 Outlier (integer format) 

Column 45-50 Temperature 1 (tenth of degrees C in integer format) 

Column 51-56 Temperature 2 (tenth of degrees C in integer format) 

Column 57-58 Sensor type (A1 for acoustic type) 

Column 59-60 blank 

Column 61-61 Data Source (S for Satellite, D for Diskette) 

Sample data: 

85169901AUG 17 2007 05:00 1138 23 0 308 297A1 D 

85169901AUG 17 2007 05:06 1126 26 0 308 298A1 D 

85169901AUG 17 2007 05:12 1107 26 1 309 298A1 D 

1.5.2.2 Pressure Sensor or Generic Data (XXX.BWL format) 

Column 1- 7 Station ID (7 digits, assigned in the project instructions) 

Column 8- 8 1 (DCP number, use 2, 3 , etc., for additional DCPs) 

Column 9-19 Date (MMM DD YYYY format, e.g. JAN 01 1998) 

Column 20-20 Blank 

Column 21-22 Hours in 24 hour format (i.e. 00, 01, ..., 23) 

Column 23-23 : (colon) 

Column 24-25 Minutes (00-54) 

Column 26-32 Data value in millimeters, right justified, (e.g. 1138) 

Column 33-38 Sigma (standard deviation in millimeters in integer format) 

Column 39-44 Outlier (integer format) 

Column 45-50 Sensor temperature (tenth of degrees C in integer format) 

Column 51-52 Sensor type (Z1 for generic or pressure) 

Column 53-53 blank

Column 54-54 Data Source (S for Satellite, D for Diskette) 

Sample data: 

85169901AUG 17 2007 05:00 1138 23 0 308Z1 D 

85169901AUG 17 2007 05:06 1126 26 0 308Z1 D 

85169901AUG 17 2007 05:12 1107 26 1 309Z1 D 

Note: pressure data must be accompanied by documented staff observations as listed in 

Section 1.2.4.2, if applicable. 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 44

 

1.5.2.3 Tabulations and Tidal Datums 

For contract surveys, the contractor shall provide digital tabulations of staff/gauge differences, 

hourly heights, high and low waters, monthly means, and water level datums for the entire time 

series of observations from each water level station. Along with the final contractor computed 

tidal datums, the contractor shall provide copies of the tide-by-tide and/or monthly mean 

simultaneous comparison sheets from which the final tidal datums were determined. Audit trails 

of data edits and gap-filling shall be summarized and provided also. 

The digital tabulation files for hourly heights, high and low waters, monthly means, and station 

datum shall have the following formats: 

Each input record (including the final record) ends with a carriage return and excludes any 

extraneous characters such as trailing blank spaces for all types of water level data (6-minute 

water level data, hourly height, high/low, monthly means, and station datum). 

1.5.2.4 Hourly Height data Format 

Column 1- 7 Station ID (7 digits, assigned in the project instructions) 

Column 8- 8 Blank 

Column 9-16 Date (YYYYMMDD format, e.g. 20070120) 

Column 17-17 Blank 

Column 18-19 Hours (2 digits 00-23, use leading zeros) 

Column 20-20 : (colon) 

Column 21-22 Minutes (2 digits 00-54, use leading zeros) 

Column 23-23 Blank 

Column 24-30 Water level value in meters (F7.3 format, e.g. 123.456) 

Sample data: 

9414290 20040101 00:00 123.456 

Hourly height data file shall be named in the following format: xxxxxxx.w2.dat, where xxxxxxx 

is the seven digit station number, w2 is the product code for the hourly heights data, and dat is 

the extension. This is the format needed when the data is loaded into CO-OPS DMS database. 

1.5.2.5 High/Low Data Format 

Column 1- 7 Station ID (7 digits, assigned in the project instructions) 

Column 8- 8 Blank 

Column 9-16 Date (YYYYMMDD format, e.g. 20070120) 

Column 17-17 Blank 

Column 18-19 Hours (2 digits 00-23, use leading zeros) 

Column 20-20 : (colon) 

Column 21-22 Minutes (2 digits 00-54, use leading zeros) 

Column 23-23 Blank 

Column 24-30 Water level value in meters (F7.3 format, e.g. 123.456) 

Column 31-31 Blank 

Column 32-33 Water level high/low type (H, L, HH, or LL)

Sample data: 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 45

 

9414290 20040101 00:00 123.456 HH 

Definition of Acronym: 

H: Higher low water level value 

L: Lower high water level value 

HH: Higher high water level value 

LL: Lower low water level value 

High and low data file shall be named in the following format: xxxxxxx.w3.dat, where xxxxxxx 

is the seven digit station number, w3 is the product code for the high/low data, and dat is the 

extension. This is the format needed when the data is loaded into CO-OPS DMS database. 

1.5.2.6 Monthly Mean Data Format 

Column 1- 7 Station ID (7 digits, assigned in the project instructions) 

Column 8- 8 Blank 

Column 9- 12 Year (YYYY format, e.g. 2007) 

Column 13- 13 Blank 

Column 14- 15 Month (in 2 digits 01-12, use leading zeros) 

Column 16- 16 Blank 

Column 17- 23 MHHW in meters (F7.3 format, e.g. 123.456) 

Column 24- 24 Blank 

Column 25- 31 MHW in meters (F7.3 format, e.g. 123.456) 

Column 32- 32 Blank 

Column 33- 39 DTL in meters (F7.3 format, e.g. 123.456) 

Column 40- 40 Blank 

Column 41- 47 MTL in meters (F7.3 format, e.g. 123.456) 

Column 48- 48 Blank 

Column 49- 55 MSL in meters (F7.3 format, e.g. 123.456) 

Column 56- 56 Blank 

Column 57- 63 MLW in meters (F7.3 format, e.g. 123.456) 

Column 64- 64 Blank 

Column 65- 71 MLLW in meters (F7.3 format, e.g. 123.456) 

Column 72- 72 Blank 

Column 73- 79 GT in meters (F7.3 format, e.g. 123.456) 

Column 80- 80 Blank 

Column 81- 87 MN in meters (F7.3 format, e.g. 123.456) 

Column 88- 88 Blank 

Column 89- 95 DHQ in meters (F7.3 format, e.g. 123.456) 

Column 96- 96 Blank 

Column 97-103 DLQ in meters (F7.3 format, e.g. 123.456) 

Column 104-104 Blank 

Column 105-111 Maximum Water Level in meters (F7.3 format, e.g. 123.456) 

Column 112-112 Blank 

Column 113-120 Maximum Water Level Date (in YYYYMMDD format, last occurrence) 

Column 121-121 Blank 

Column 122-123 Maximum Water Level Hour (2 digits 00-23, use leading zeros) 

Column 124-124 : (colon) 

Column 125-126 Maximum Water Level Minute (2 digits 00-54, use leading zeros) 

Column 127-127 Blank 

Column 128-128 Maximum Water Level occurrences (1 digit) 

Column 129-129 Blank 

Column 130-136 Minimum Water Level in meters (F7.3 format, e.g. 123.456) 

Column 137-137 Blank 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 46

 

Column 138-145 Minimum Water Level Date (in YYYYMMDD format, last occurrence) 

Column 146-146 Blank 

Column 147-148 Minimum Water Level Hour (2 digits 00-23, use leading zeros) 

Column 149-149 : (colon) 

Column 150-151 Minimum Water Level Minute (2 digits 00-54, use leading zeros) 

Column 152-152 Blank 

Column 153-153 Minimum Water Level occurrences (1 digit) 

Sample data (with column ruler): 

 0 0 0 0 0 0 0 0 

 1 2 3 4 5 6 7 8 

12345678901234567890123456789012345678901234567890123456789012345678901234567890 

9414290 2004 01 123.456 123.456 123.456 123.456 123.456 123.456 123.456 123.456 

 0 1 1 1 1 1 1 

 9 0 1 2 3 4 5 

1234567890123456789012345678901234567890123456789012345678901234567890123 

123.456 123.456 123.456 123.456 20040101 00:00 1 123.456 20040101 00:00 1 

Definition of Acronym: 

MHHW Mean Higher High Water 

MHW Mean High Water 

DTL Diurnal Tide Level 

MTL Mean Tide Level 

MSL Mean Sea Level 

MLW Mean Lower Water 

MLLW Mean Lower Low Water 

GT Great Diurnal Tide Range 

MN Mean Range of Tide 

DHQ Diurnal High Water Inequality 

DLQ Diurnal Low Water Inequality 

MAX_WL Maximum Water Level during the Month measurement period 

MAX_DATE Date of Maximum Water Level 

MAX_HOUR Hour of Maximum Water Level 

MAX_MIN Minute of Maximum Water Level 

MAX_OCCUR Number of occurrences during the month the Water Level meets the 

MAX_WL 

MIN_WL Minimum Water Level during the Month measurement period 

MIN_DATE Date of Minimum Water Level 

MIN_HOUR Hour of Minimum Water Level 

MIN_MIN Minute of Minimum Water Level 

MIN_OCCUR Number of occurrences during the month the Water Level meets the 

MIN_WL 

Monthly Means data file shall be named in the following format: xxxxxxx.w5.dat, where 

xxxxxxx is the seven digit station number, w5 is the product code for the monthly means data, 

and dat is the extension. This is the format needed when the data is loaded into CO-OPS DMS 

database. 

1.5.2.7 Station Datum Data Format

Column 1- 7 Station ID (7 digits, assigned in the project instructions) 

Column 8- 16 Blank 

Column 17- 23 MHHW in meters (F7.3 format, e.g. 123.456) 
Water Level Station Specifications and Deliverables

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Column 24- 24 Blank 

Column 25- 31 MHW in meters (F7.3 format, e.g. 123.456) 

Column 32- 32 Blank 

Column 33- 39 DTL in meters (F7.3 format, e.g. 123.456) 

Column 40- 40 Blank 

Column 41- 47 MTL in meters (F7.3 format, e.g. 123.456) 

Column 48- 48 Blank 

Column 49- 55 MSL in meters (F7.3 format, e.g. 123.456) 

Column 56- 56 Blank 

Column 57- 63 MLW in meters (F7.3 format, e.g. 123.456) 

Column 64- 64 Blank 

Column 65- 71 MLLW in meters (F7.3 format, e.g. 123.456) 

Column 72- 72 Blank 

Column 73- 79 GT in meters (F7.3 format, e.g. 123.456) 

Column 80- 80 Blank 

Column 81- 87 MN in meters (F7.3 format, e.g. 123.456) 

Column 88- 88 Blank 

Column 89- 95 DHQ in meters (F7.3 format, e.g. 123.456) 

Column 96- 96 Blank 

Column 97-103 DLQ in meters (F7.3 format, e.g. 123.456) 

Column 104-104 Blank 

Column 105-111 Maximum Water Level in meters (F7.3 format, e.g. 123.456) 

Column 112-112 Blank 

Column 113-120 Maximum Water Level Date (in YYYYMMDD format, last occurrence) 

Column 121-121 Blank 

Column 122-123 Maximum Water Level Hour (2 digits 00-23, use leading zeros) 

Column 124-124 : (colon) 

Column 125-126 Maximum Water Level Minute (2 digits 00-54, use leading zeros) 

Column 127-127 Blank 

Column 128-128 Maximum Water Level occurrences (1 digit) 

Column 129-129 Blank 

Column 130-136 Minimum Water Level in meters (F7.3 format, e.g. 123.456) 

Column 137-137 Blank 

Column 138-145 Minimum Water Level Date (in YYYYMMDD format, last occurrence) 

Column 146-146 Blank 

Column 147-148 Minimum Water Level Hour (2 digits 00-23, use leading zeros) 

Column 149-149 : (colon) 

Column 150-151 Minimum Water Level Minute (2 digits 00-54, use leading zeros) 

Column 152-152 Blank 

Column 153-153 Minimum Water Level occurrences (1 digit)

Sample data (with column ruler): 

 0 0 0 0 0 0 0 0 

 1 2 3 4 5 6 7 8 

12345678901234567890123456789012345678901234567890123456789012345678901234567890 

9414290 123.456 123.456 123.456 123.456 123.456 123.456 123.456 123.456 

 0 1 1 1 1 1 1 

 9 0 1 2 3 4 5 

1234567890123456789012345678901234567890123456789012345678901234567890123 

123.456 123.456 123.456 123.456 20040101 00:00 1 123.456 20040101 00:00 1 

Definition of Acronyms for Station Datum data are same as that for the Monthly Mean data. 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 48

 

Station datum data file shall be named in the following format: xxxxxxx.w7.dat, where xxxxxxx 

is the seven digit station number, w7 is the product code for the station datum data, and dat is the 

extension. This is the format needed when the data is loaded into CO-OPS DMS database. 

If the Greenwich high water interval (HWI) and Greenwich low water interval (LWI) are 

available, then contractor shall provide that information in F5.2 format (e.g. xx.xx) and that file 

shall be named as station#.GWI.txt. Generally the interval values should be between 0.0 and 

12.41. 

1.5.3 Submission and Deliverables – Documentation and Time lines 

The check-off list in Figure 1.9 (in Section 1.5.1) shall be used to check and verify the 

documentation that is required for submission. All documentation, water level data, processed 

data including hourly height, high/low data, monthly means data, and station datums data, GPS 

OPUS results, other reports as required, shall be forwarded within 15 business days of the 

removal of the water level stations/gauges, or as specified in the contract. 

All data and documentation shall be submitted to NGS. All data and documentation that is 

submitted shall be retained by the contractor for a period of not less than three years or as 

stipulated in the contract, whichever is longer. 

All data and documentation shall be submitted in digital format. Please refer to Section 1.5.1, 

1.5.2, and below for details about various data and documentation. 

The station documentation generally includes, but is not limited to the following: 

(1) Transmittal letter (PDF format) 

(2) E-Site Report, or Water Level Station Xpert Site Report, or Tide Station Report (E-Site 

report in web based electronic format, Water Level Station Xpert Site Report or Tide Station 

report in Microsoft Excel format) 

(3) Google Chartlet, or NOAA Chartlet with chart number or map name and scale shown. (JPEG 

format) 

(4) Name of the U.S. Geological Survey quadrangle map (7.5 seconds interval) indicating the 

exact location of the station, with map name and scale shown (JPEG format) 

(5) Sensor test worksheet (PDF format) 

(6) Sensor elevation drawing (PDF format) showing sea floor, pier elevation, and sensor 

elevation if the sensor is mounted vertically. 

(7) Water level transfer form (for Great Lakes stations only in PDF format) 

(8) Barometer Installation Worksheet (for Great Lakes stations only in PDF format) 

(9) Bench mark sketch (PDF format) – Large-scale bench mark location sketch of the station site 

showing the relative location of the water level gauge, staff (if any), bench marks, and major 

reference objects found in the bench mark descriptions. The bench mark sketch shall include 

an arrow indicating north direction, a title block, and latitude and longitude (obtained from 

hand-held GPS receiver) of the gauge. 

(10) Bench mark descriptions with handheld GPS coordinates (d/m/s.x format), and “Station To 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 49

 

Reach” statement (in Microsoft Word format) (Refer to User’s Guide for Writing Bench 

Mark Descriptions, NOAA/NOS, Updated January 2003). 

(11) Digital photographs of bench mark disk - close-up and eye level view of setting, bench mark 

locations from two different (perpendicular) horizontal cardinal directions, station, DCP, 

equipment, underwater components, and vicinity (JPEG format) 

(12) Levels (raw) (electronic files) including leveling equipment information and field notes of 

precise leveling, if applicable. 

(13) Abstract of precise leveling (electronic format) 

(14) Datum offset computation worksheet or Staff/Gauge difference work sheet as appropriate 

showing how sensor “zero” measurement point is referenced to the bench marks. 

(15) Staff to gauge observations, if applicable (in Microsoft Excel format) 

(16) Calibration certificates for Invar leveling rods, if applicable (in PDF format) 

(17) Calibration records for sensors, if applicable (in PDF format) 

(18) Agreements, MOU, contract documents, utilities/pier agreements, etc., if applicable (in PDF 

format) 

(19) Other information as appropriate, or as specified in the contract (in PDF format) 

(20) Water level data download in specified format 

(21) GPS Deliverables - the OPUS DB datasheet and four photos of the GPSBM in electronic 

format for each observation for each water level station as described in the User’s guide for 

GPS Observations At Tide and Water Level Bench Marks. 

For long term water level stations (more than 1 year), the bench mark sketch, chartlet, and "To 

Reach" statement need only be submitted if those items have been revised after the initial 

submission. When using the electronic/barcode system, the data of the abstract and bench mark 

description or recovery notes shall be submitted. For optical levels, submit the raw levels and 

the leveling abstract. 

For submission in electronic format, the station documentation shall be organized by various 

folders under the main station number folder, and then pertinent information shall be placed in 

the various folders and submitted on a digital media such as DVD/CD-ROM etc. 

Here is an example of submission of the electronic folders for San Francisco tide station: 

9414290 San Francisco FY 08 Installation 

/Transmittal letter 

/Calibration records for sensors, if applicable 

/Site Report or tide station report 

/Chartlet and USGS Quad maps 

/Sensor test worksheet 

/Sensor elevation drawing 

/Bench mark sketch 

/“Station To Reach” statement 

/Bench mark descriptions 

/Photographs of bench marks, station, DCP, equipment, and vicinity in digital format 

/Levels (raw) (electronic files) and field notes of precise leveling 

/Abstract of precise leveling 
Water Level Station Specifications and Deliverables

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/Staff to gauge observations, if applicable 

/Datum offset computation worksheet or Staff/Gauge difference work sheet (elevation of 

sensor zero measurement point referenced to bench marks) 

/Calibration certificates for Invar leveling rods, if applicable 

/Agreements, MOU, contract documents, utilities/pier agreements, etc., if applicable 

/Other information as appropriate, or as specified in the contract 

/Water level data (6-minute, hourly heights, high/low, monthly means, station datum) 

/GPS data and documentation 

Submit required GPS deliverables OPUS results and 4 photos of GPSBM on a separate digital 

media, such as DVD/CD-ROM, FTP sites, etc. For example, GPS submission for San Francisco 

tide station will be as follows: 

9414290 San Francisco FY 08 Annual Inspection 

/GPS deliverables 

/Photos of GPSBM 

Submit the completed station package to: 

Mr. George Leigh 

Contracting Officers Representative 

NOAA/NOS/National Geodetic Survey 

SSMC 3, Station # 8609 

1315 East-West Highway 

Silver Spring, MD 20910-3281 

Tel # 301-713- 3167 

1.6 Guidelines and References 

References for the water level measurement and leveling requirements issued by the NOS Center 

of Operational Oceanographic Products and Services (CO-OPS) and the National Geodetic 

Survey (NGS) are listed below. 

Most of these documents are available on CO-OPS web site at 

http://tidesandcurrents.nos.noaa.gov. 

1. Next Generation Water Level Measurement System (NGWLMS) Site Design, P 

reparation, and Installation Manual, NOAA/NOS, January 1991. 

2. User’s Guide for the Installation of Bench Marks and Leveling Requirements for Water 

Level Stations, NOAA/NOS, dated October 1987. 

3. User’s Guide for Writing Bench Marks Descriptions, NOAA/NOS, Updated January 

2002. 

4. User’s Guide for Electronics Levels, NOAA/NOS, updated January 2003. 

5. User’s Guide for 8200 Bubbler Gauges, NOAA/NOS, updated February 1998. 
Water Level Station Specifications and Deliverables

For Shoreline Mapping Projects, May 2009 Page 51

 

6. User’s Guide for 8200 Acoustic Gauges, NOAA/NOS, updated August 1998. 

7. User’s Guide for 8210 Bubbler Gauges, NOAA/NOS, updated February 2001. 

8. User’s Guide for GPS Observations At Tide and Water Level Station Bench Marks, 

NOAA/NOS, updated November 2008. 

9. Tidal Datums and Their Applications, Special Publication No. CO-OPS 1, NOAA/NOS, 

June 2000. 

10. Manual of Tide Observations, U.S. Department of Commerce, Publication 30-1, 

Reprinted 1965. 

11. Tidal Datum Planes, U.S. Department of Commerce, Special Publication No.135, 

Marmer 1951. 

12. Tide and Current Glossary, U.S. Department of Commerce, NOAA, NOS, October 1989. 

13. Standing Project Instructions: Great Lakes Water Levels, June 1978. 

14. NOAA Technical Report NOS 64 “Variability of Tidal Datums and Accuracy in 

Determining Datums from Short Series of Observations”, Swanson, 1974. 

15. Data Quality Assurance Guidelines for Marine Environmental Programs, Robert J. 

Farland, Office of Ocean Engineering, NOAA, March, 1980. 

16. System Development Plan, CORMS: Continuous Operational Real-Time Monitoring 

System, NOAA Technical Report NOS OES 014, U.S. Department of Commerce, 

NOAA, NOS February, 1997. 

17. NGWLMS GOES MESSAGE FORMATTING, Phil Libraro, 1/2003. 

18. Computational Techniques for Tidal Datums, NOAA Technical Report NOS CO-OPS 2, 

U.S. Department of Commerce, NOAA, NOS, DRAFT December 1998. 

19. Standards and Specifications for Geodetic Control Networks, Federal Geodetic Control 

Committee, September 1984. 

20. NOAA Technical Memorandum “NOS NGS-58, Guidelines for Establishing GPSDerived Ellipsoid Heights (Standards 2 cm and 5 cm), Version 4.3", November 1997. 

21. Geodetic Leveling, NOAA Manual NOS NGS 3, U.S. Department of Commerce, NOAA, 

National Ocean Survey, August, 1981. 

22. Xpert Operations and Maintenance Manual, October 2006.