In 1938, Ernst Antevs research on the Rainfall and Tree Growth in the Great Basin was published. A segment concerns Lassen and Modoc Counties. The following is an interesting footnote from that study: “The sources of Pine Creek, the only large tributary of Eagle Lake, are less than a mile from those of the Susan River, the main feeder of Honey Lake. The seasonal runoff in these streams may therefore undergo similar fluctuations, and with undisturbed conditions, the lakes should do the same. Actually, Honey Lake has fluctuated in harmony with the known precipitation of the region, but this has not been the case with Eagle Lake. The moistest times since 1850 have been 1868, 1890-93 and 1904-07, and since 1907 the measured rainfall and runoff have on the whole decreased, while the highest recent stand in Eagle Lake was recorded in 1917. The fact that from 1801 to 1821 a thicker wood mantle was formed in the Susanville trees than during any two later decades prevents us from concluding from the stump at the 82 foot level that the precipitation from 1760 to 1860 was continuously light and much smaller than it has been since 1860. In short, the levels of Eagle Lake cannot be used as a basis for conclusions about the rainfall before 1850. A reasonable explanation of this controversial problem was given the writer in 1931 by Mr. G.N. McDow, president of Lassen County Abstract Co., Susanville, who expressed the opinion that the rise of Eagle Lake was due to a closing of its subterranean outlet about 1890 by an earthquake.”
