The Seattle area experienced record rainfall in October. Over 9”, more than double the 3.5” average.
On Orcas, rain was recorded on all but a handful of days last month, but our 6.5” of rainfall did not break any records. Below is a chart of the rainfall Eastsound Water recorded last month, compared to previous Octobers.
October is a month of rather high rainfall variability. October can be an extension of the dry summer season, or it can be the beginning of the wet winter season. To the right is a graph of the last 16 years of October precipitation records collected by Eastsound Water.
You might suspect that with a wet October our Purdue Reservoir has begun refilling rather rapidly. Indeed over the month of October, the lake gained 1 ft, (from 13.5 ft to 14.5 ft.), and the lake level is slightly higher than “normal” at this time of year.
Eastsound Water staff measured almost 7” of rainfall at Purdue, but that much rain, falling on 385 acres of uphill terrain would should a much larger impact on the water level in our 11-acre reservoir. However, every fall there is a significant “delayed reaction” when it comes to refilling the reservoir. Most of October’s precipitation was “absorbed” by the dry ground in our forests and very little ended up “running off” into the lake. Over November and December, the water level at Purdue will hopefully gain another 5.5’ and begin overflowing.