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The Commission is the recognized authority for determining the location of the ordinary high water mark in California. The United States Supreme Court has ruled that in tidal areas the boundary is to be located by identifying the intersection of the mean high tide line with the shore ( Borax Consol., Ltd v. Los Angeles (1935) 296 U.S. 10).
Mean Higher-High Water: MHW: Mean High Water: MTL: Mean Tide Level: MSL: Mean Sea Level: DTL: Mean Diurnal Tide Level: MLW: Mean Low Water: MLLW: Mean Lower-Low Water: STND: Station Datum: GT: Great Diurnal Range: MN: Mean Range of Tide: DHQ: Mean Diurnal High Water Inequality: DLQ: Mean Diurnal Low Water Inequality: HWI: Greenwich High Water ...
The elevation of the highest predicted astronomical tide expected to occur at a specific tide station over the time period of 40 years. The 40 years period will include 2 National Tidal Datum Epoch periods. This time period will be updated every 20 years. The present values are based on the time period of 2000-2040.
The plots show the monthly highest and lowest water levels with the 1%, 10%, 50%, and 99% annual exceedance probability levels in red, orange, green, and blue. The plotted values are in meters relative to the Mean Higher High Water (MHHW) or Mean Lower Low Water (MLLW) datums established by CO-OPS (1 foot = 0.3 meters).
Federal regulations define the ordinary high water mark (OHWM) as “that line on the shore established by the fluctuations of water and indicated by physical characteristics such as a clear, natural line impressed on the bank, shelving, changes in the character of soil, destruction of terrestrial vegetation, the presence of litter and debris, or other appropriate means that consider the ...
Tide —The vertical rise and fall of the sea as caused by the moon and the sun. In mid ocean, it is six hours and 20 minutes between high and low water. Near the coastline and particularly at the mouths of large rivers and estuaries, the period can vary slightly. Tides vary because of the moon's proximity, phase and declination.
Oct 12, 2009 · Much of the San Francisco Bay Area (especially the South Bay) has subsided. All of the Delta has. The new “legal” mean-high-water line thus lies in many cases landward — far landward — of where it had been thought to be. As sea level continues to rise, the mean-high-water line will continue to encroach ever farther landward.
