Opinion ID: 1165790
Heading Depth: 1
Heading Rank: 3

Heading: The Nature of Tides

Text: Tides are the result of gravitational attraction of the moon and sun upon the waters of the earth. Their heights vary with the changing positions of the moon, sun and earth in relation to each other. Changes in winds, barometric pressures, and the freshets or droughts of rivers, together with the geography of the locale, will cause tides to be higher or lower than predicted by the United States Coast and Geodetic Survey. There are usually two high and two low waters or tides a day. They may be designated, lower low water, low water, high water and higher high water. The datum (plane of reference) from which the heights of tides are calculated on the Pacific Coast (with the exception of Balboa, Panama) is the mean or average of the lower of the two low waters of each day. [16] In Marmer, Tidal Datum Planes, p. 86 (U.S. Dep't of Commerce, Coast and Geodetic Survey, Special Pub. No. 135, rev. ed. 1951), it is stated: In view of the variations to which the height of high water is subject, mean high water [tide] at any place may be defined simply as the average height of the high waters at that place over a period of 19 years. In its findings of fact, the trial court stated: mean high tide of the Pacific Ocean is defined as the average elevation of all high tides as observed at a location through a complete tidal cycle of 18.6 years, and the actual western boundary line of plaintiff's property is where that elevation meets the shore as it exists at any particular time. (Italics ours.) Since the line of mean high tide is an average over a period of years of the two daily high tides, one being higher than the other, it is apparent that the higher high tide will wash inland from the line of mean high tide. This is illustrated by an exhibit showing the observed high tide on January 23, 1963 at a point a few feet south of plaintiff's property to have been 130 feet inland from the line of predicted mean high tide. The difference in elevation was 3 feet. In the instant case, in front of plaintiff's property the distance between the line of  ordinary high tide in 1889, as defined by the state, and  mean high tide, as presently determined by the United States Coast and Geodetic Survey and adopted by the trial court, is 561 feet; the difference in elevation is 14.25 feet. The problem presented is pinpointed by one author as follows: Boundaries determined by the course of the tides involve two engineering aspects: a vertical one, predicated on the height reached by the tide during its vertical rise and fall, and constituting a tidal plane or datum, such as mean high water, mean low water, etc.; and a horizontal one, related to the line where the tidal plane intersects the shore to form the tidal boundary desired, for example, mean high-water mark, mean low-water mark.... The first is derived from tidal observations alone, and, once derived (on the basis of long-term observations), is for all practical purposes a permanent one. Shalowitz, 1 Shore and Sea Boundaries 89 (United States Department of Commerce 1962). (Italics ours.) Mean high tide is measurable and determinable. [3] On the other hand, the line of ordinary high tide as used in article 17 of the constitution is not a term of technical exactness. It is indefinite at best and an oversimplification of a phenomenon inherently complex and variable. In the absence of any indication to the contrary, we deem the word ordinary to be used in its everyday context. The line of ordinary high tide is not to be fixed by singular, uncommon, or exceptionally high tides, but by the regular, normal, customary, average, and usual high tides. One cannot sit and watch the tide reach its stand at different elevations on each turn as it ebbs and floods without realizing that a line to be fixed by it must be based upon an average. Thus the line of ordinary high tide is the average of all high tides during the tidal cycle.