I started measuring the depth of Goldstream Creek a little over a year ago this week. Each morning I measure down from a particular spot on the bridge over the Creek to the top of the water or ice and report this (plus daily high and low temperature, precipitation, snowfall and snow depth) to the Weather Service. The following plot (if nothing shows up, click the following links to view a PNG or PDF version) shows the depth of the Creek at our swimming hole on the top, and the daily high and low temperatures on the bottom. The dark cyan line on the top plot is the height of the bridge (about six feet below the entrance to our house), and the dark cyan line on the lower plot is the freezing point.
At it’s highest, the Creek was just over two feet from the bottom of the bridge, the slough flooded into the dog yard about two thirds of the way across the lowest point, and the Creek seemed dangerously close to topping the banks. The photo at the top shows the back cabin during the high water event.
This year’s breakup was similar to last year: ground and meltwater from the surrounding area started flooding on top of the ice and over the course of a couple weeks, it eroded the ice below until the water level rapidly dropped to more normal summertime depths. One interesting note is that we seem to get a large pulse of water (the rise starting around March 11th) before the snow has started melting, which would seem to indicate that the first pulse is coming from groundwater sources. We don’t start getting afternoon temperatures above freezing until the beginning of April, and this is when snowmelt starts bringing the level up even higher.
When the level begins to drop, it’s pretty dramatic as we go from bankfull conditions to almost nothing in a week. This year we’ve still got wide shelves of ice hanging on the banks six feet above the level of the water.
The plot also shows the brief ice storm in late November where we got a couple inches of rain that froze on the roads and brought the Creek up slightly.
In the past, we’ve had more dramatic breakups where the initial springtime pulse of ground and meltwater breaks up all the ice in a couple days and sends it past our house crashing and grinding, but even the more gradual melting pattern of the last two years is impressive in how quickly the Creek rises and falls.