Streamflow records show that 1904 was a year of very heavy runoff, and East Lake was no doubt slightly higher in 1904 than when Russell saw it in 1903.
The lake is known to have reached a stage of 6,382.5 feet in 1958. At that time, many trees on the sloping southwest shore were undermined at the high-water level, some of them remaining erect and others becoming tilted, much like those described by Russell and Lawrence. Along the shores of the lake, lodgepole pine trees as much as 43 years of age and as much as 13 inches in diameter were drowned in 1958. Some of the trees became established as seedlings at a level several feet below the high stage of 1958; the lowest one observed, a lodgepole pine, had its upper roots at 6,374.5 feet altitude, or 8.0 feet lower than the high level of 1958 (fig. 7).
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| Figure 7.-View eastward from southwest shore of East Lake on July 2, 1963, when water level was 4.7 feet below high level of 1958. Lodgepole pine trees in foreground were drowned when the lake rose over their root systems; former forest road in partial shade near right in view was submerged and covered with lumps of floating pumice in 1958. |
The high level of 6,382.5 feet reached in 1958 has been exceeded at some time in the past. An older beach terrace occurs along the northeast shores of the lake at an altitude of 6,385.5 feet. The largest living lodgepole pine trees on that terrace were found to have germinated about 1853, 1879, and some time before 1889; hence, the terrace was apparently formed by a high stage that occurred prior to 1853.
No positive evidence was observed of lake stages higher than about 6,385.5 feet. A few large yellow pine trees are living along the steep and rocky north shore of the lake and are rooted at levels 6 to 10 feet higher than the high level of 1958. Core borings of some of these trees were taken in September 1960 by D. B. Lawrence and the writer. The growth rings of one such living tree showed that it germinated before 1850, at altitude 6,388.4 feet; another, at 6,391.2 feet, germinated before the year 1574. A large yellow pine snag at 6,389.1 feet had lived about 283 years before dying many years ago. At 6,387.2 feet, the roots of a dead yellow pine appear to have been eroded away, possibly by waves carrying floating lumps of pumice, but no beach line was found at that level. If East Lake did reach that level, it may have done so in the period 1805-25, when tree growth in eastern Oregon was unusually rapid and precipitation was probably much above average (Antevs, 1938, p. 66; Keen, 1937, figs. 7, 8). The oldest tree cored was a large yellow pine that germinated in or before the year 1439; its base was, by hand leveling, 165 feet above the water level of September 1960.
In summary, all the botanical evidence indicates that the high level of 6,382.5 feet in 1958 duplicated the high level of 1904, which was the highest since some time before 1853, when the lake level reached 6,385.5 feet.
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