data, and Figure 18 compares the distribution of daily high and low water levels and hourly tide 

 heights. The monthly or annual mean sea level (MSL) reported is the average of the hourly heights, 

 whereas the mean tide level is midway between mean high water (MHW) and mean low water 

 (MLW), which are the averages of the daily high- and low-water levels, respectively, relative to 

 NGVD, Mean range (MR) is the difference between MHW and MLW levels, and the lowest water 

 level for the month is the extreme low (EL) water, while the highest water level is the extreme high 

 (EH) water level. 



38 



