Thursday, December 6, 2007

Winberry Cr nr Lowell

Winberry Creek is one of the two creeks flowing into Fall Creek Reservoir west of Eugene Oregon. Fall Creek flows into the Middle Fork Willamette River above the Coast Fork and these two rivers form the beginning of the Willamette River flowing through Eugene, Oregon and north in the Willamette Valley to Portland, and into the Colmbia River.

The gage is the typical Oregon stilling well gage, with a 48-inch well and walk-in house, see similar one for Naselle River. The gage has a unique slope gage not typical with gages. There are stairs from the gage platform to the water and on one side of the support beam going down the length of the stairs are marks for the water depth in feet.

Normally outside gages are vertical staff gages, usually posts with gage plates marked in hundredths, tenths and feet to establish the stage, or water level, of the river. All the instruments in the gage are calibrated to inside and outside gages, and the stage can then be calibrated to the stage-discharge rating with discharge measurements, which you can read an explanation.

A vertical gage, often several from the lowest stage to the highest are usually 3-6 feet foot high posts positioned up the bank to the gage house, and sometimes on the side of the gage house if the water can potentially get that high. In some places, however, a vertical staff gage isn't feasible due to site condition or river conditions. An example is Alaska where the winter ice and spring break up will literally rip these gages apart, so levels are run every visit to get an outside stage value.

Winberry creek has a slope gage because in the long run it was the easiest to install when the gage was established. It's harder to set and calibrate a slope gage with survey levels, and requires more frequent checking to ensure the marks are accurate if the staircase moves or settles in the bank. And it also made it safer from vandals who often like to knock vertical staff gages over.

Anyway, I've wandered a bit. The gage is alongside a rural (dead-end) road above Fall Creek Reservoir. You can't miss it but the locals know it's there and so few people live in the area, there has never been any problems with vandalism. It's an easy gage to service and all measurements are made by wading near the gage or the cableway just downstream. It's one of those gages that makes streamgaging easy and enjoyable for a change.

It also taught me a think about water, especially freezing water. One December field trip the weather was below freezing. Everything was frozen or covered in ice or frost. I'm not fond of streamgaging in very cold weather, I can't bundle up enough to stay warm. Well, one of the standard tasks streamgagers do at gages with each service is to measure the air and water temperature. The air temperature was obvious, damn cold.

But it was the water temperature that was interesting. I measured a -.2 degrees Centigrade. The water in the creek was below freezing but the surface ice on the water was only along the six inches along the bank. The rest of the creek water had sufficient flow to keep from freezing. To check this, and I had my hipboots already on to make a wading measurement, I waded across the creek taking temperature reading. It was consistently -0.2 +/1 0.1 degree Centigrade.

I realize this flies in the face of what people have learned in school, that water freezes at 0.0 degrees Centigrade, or 32 degree Fahrenheit, but a physicist can explain that if you add velocity to any liquid, including water, the movement can prevent the liquid from freezing at its normal freezing temperature. And an article I read since then has proven that water can reach temperatures of -0.5 or more degrees and still not freeze. The trick is the movement.

The flow in Winberry Creek during the measurement measured near zero as water along banks do, was freezing on the surface. The flow in the channel was between 2 and 4 feet per second, just enough to keep it moving as it lost heat to the atmosphere and get just below freezing without freezing. While almost everyone since then has argued my thermometer was wrong - which has annual calibration tests, they weren't there to see it for real.

I serviced the gage and made the discharge measurement. But the measurement wasn't fun. Standing in this water for about 40 minutes was really damn cold. My toes were turning blue - with hipboots your only warmth is socks, big wool socks. Not enough to keep my body through the hipboots from losing heat to the water. It was one of those field trip where at the end you sit on the tailgate of the truck with your coffee and just let the world go by for a few minutes.

The stillness of the morning, the coldness of the air, and a job finished feeling satisfied was worth the whole time, albeit my toes and hands might disagree. But then there were other days here which also added to the memory of this gage.

Jack Mrowka (PhD), see tribute, was a professor at the University of Oregon when I started my work with the USGS. I walked into his office one day after work because I was told he taught water resources. That began a long friendship which we followed as our career moved us around the West, myself to Arizona and Washington, and Jack to Santa Rosa and Sacramento, California.

There were a number of adventures we went on in the name "research", mostly his, but sometimes jointly with my work. He showed me the USGS method for making discharge measurements had some flaws that could bias the measurement, but the method is basically sound as a common standard method. But it was Winberry Creek he had his best moment of surprise for me.

In his water resources class Jack taught about collecting, computing and producing streamflow data. But until we became friends he couldn't show how the field work was done by the USGS. One fall day I was at this gage and was just enjoying the quiet warm morning. The day was scheduled to service this gage and later the Fall Creek near Lowell gage, the other inflow into Fall Creek Reservoir. The following day was the reservoir gage and the Fall Creek below the reservoir gage.

I was in the gage house when I heard the sound of a bus. It seemed odd as there were only a few houses past the gage and the road dead-ended about a mile later. The sound of the bus stopped right at the gage. I stepped out to see why, and after the doors of the bus opened Jack stepped out. He had brought his whole class to see a streamgage and for me to show them streamgaging.

"Yippee" wasn't my first thought. But Jack had an infectuous spirit and smile, and it wasn't hard to enjoy a morning teaching 30 freshman-sophomore students about streamflow gages and streamgaging. I learned later that he called the office (I had told him the week before I would be on my field trip that week) to see where I was and get permission to interrupt my work. My boss thought it was cool, laughed and said, "Go ahead."

On another field trip, on my time, we took the class to the road end and walked the creek looking at the hydrology and biology of the creek. I don't know what the students thought of the two days in the field, but for me, it was part of the enjoyment of being a streamgager. And all the office hydrology (as many hydrologists are these days) won't change the reality of being there.

I learned sometimes the most ordinary of things can bring some of the best memories.

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