Stations’ vertical values are given to 1 decimal place if they are from GPS/GNSS observation (Obs) or vertical angle measurements (Vert Ang). When a station’s elevation has been found by precise leveling but non-rigorous adjustment, it is called Computed. Another category is Posted, which indicates that the station was adjusted after the general NAVD adjustment in 1991. There is Adjusted, which are given to 3 decimal places and are derived from least squares adjustment of precise leveling. There are 13 sources of vertical control values shown on NGS data sheets. When a date is shown in parentheses after NAD83 in the data sheet, it means that the position has been readjusted. Horizontal values may be either Scaled, if the station is a benchmark or Adjusted, if the station is indeed a horizontal control point. However, these old values may be shown under Superseded Survey Control. Adjustments to NAD27 and NGVD29 datums are a thing of the past. When the height is derived from GPS/GNSS observation, a geoid model must be used to determine the orthometric height. The orthometric height in meters is listed as “ORTHO HEIGHT” and followed by the same in feet. Under the heading, “Current Survey Control,” you will find the latitude and longitude of the station in NAD83 which is fixed to the North American plate, currently in NAD83 (2011), and its height in NAVD88. Even though the station is located in the area covered by the quad sheet, it may not actually appear in the map. Geological Survey (USGS)-7.5 minute quad name follows. The PID is also found all along the left side of each data sheet record and is always two upper case letters followed by four numbers. Either of these may be used to search for the station in the NGS database. This is followed by the station’s designation, which is its name, and its Point Identification, PID. There are several, and among them are Continuously Operating Reference Station, Federal Base Network Control Station, and Cooperative Base Network Control Station. Then the station’s category is indicated. The first line of each data sheet includes the retrieval date. In addition to the latitude and longitude, the published data include the state plane coordinates in the appropriate zones. There is a good deal of information about the passive survey monuments on each individual sheet. That utilization should be informed by an understanding of the datasheet that accompanies each station and is easily available online. They can provide reliable control when properly utilized. Monuments that are the physical manifestation of the National Spatial Reference System (NSRS) and can be occupied with survey equipment are known as passive marks. These sheets have a great deal of excellent information concerning the coordinates, the quality, and many of the details about existing control points that can be used as checkpoints in any GPS/GNSS survey. You can retrieve sheets that are similar to what you see in the illustration. Brass tablets and brass caps have been set around the United States by the National Geodetic Survey also known as passive marks. When forecasted flows are predicted to reach near-flood or "action" levels, check weather and flood forecasts frequently and pay attention to any changes in the forecast.One of the things that is very useful is understanding the existing control that is currently available. High water level terms like action, minor, moderate, and major are defined by the National Weather Service. Click the "Auto Refresh" button above each graph to retrieve the most current information. Current and forecasted river levels are linked below for the South Fork Nooksack River at Saxon Bridge, Nooksack River at North Cedarville, and Nooksack River at Ferndale. Please note freezing weather may affect river gauges and limit real time data collection. NOAA Tidal Surge Information for Cherry Point.USGS Streamflow Data for Washington - Scroll down the list to find real-time streamflow data for the Whatcom Creek and Lake Whatcom Basin, Nooksack River Basin, and Sumas River Basin.10-Day Forecast - This site provides the best 10-day advanced river level forecast for rain events.Click on the symbols in the Nooksack River basin for detailed information at that river gauge location. Use the links below to check current river levels and forecasts around the region. Environment Canada Public Weather Alerts.University of Washington Department of Atmospheric Sciences.Current watches, warnings, or advisories for Whatcom County.
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