The black line shows the surface tide elevation relative to mean lower low water ( MLLW ).
2.
The tidal maximum ( mean higher high water ) is and extreme low water is-3.5 compared to mean lower low water.
3.
Though references to levels on USGS charts are made relative to Mean Lower Low Water ( MLLW ) leading to difficulty over the management of the lake's levels.
4.
The lighthouse is located on Stratford ( or Middleground ) Shoal which is a little over a mile in diameter and as little as nine feet below mean lower low water.
5.
This area is now called the Ultonia Ledge, located a mile and a half southeast of Boston Light, and is as shallow as 21 feet at mean lower low water according to modern nautical charts.
6.
Water depths range from about 14 meters ( 45 feet ) at Mean Lower Low Water ( MLLW ) at the foot of the anchorage, to about 8 meters ( 26 feet ) MLLW at the shallowest berths towards the northern end of the anchorage.
7.
Exactly how this is chosen depends on the tidal regime in the area being charted and on the policy of the hydrographic office producing the chart in question; a typical definition is Lowest Astronomical Tide ( the lowest tide predictable from the effects of gravity ), or Mean Lower Low Water ( the average lowest tide of each day ), although MSL is sometimes used in waters with very low tidal ranges.
8.
Consequently there are very little fresh water input other than winter rains & Most of the vegetation is characteristic of the low and middle littoral zones and is completely inundated by a 1.8 m tide ( Mean Lower Low Water ) . A list of major plants in the marsh was also provided : cordgrass ( dominant plants at lower elevation ), pickleweed and saltwort ( dominant in middle elevation ), seablite, saltgrass, sea lavender, arrowgrass, Jaumea carnosa, and Frankenia grandiflora.
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