'Tot Gauge Off?

[davidbob]

According the Internet gauge, the water on the Cossatot only fluctuated .2" yesterday (5-31), from 4.1 to 4.3. We thought the difference was much greater, and that the flow when we went through the Falls section was more like 4.5". It was rising while we ate lunch at Dead Dog Beach, kept was rising the rest of the way to Hwy 4, and was still on the rise after we got there.

We met the Park Ranger (nice guy) coming out of Ed Banks on the back end of the shuttle, and he said the same thing. He estimated it was running 6.5" (that was about 3:30). I don't think it was that high, but it was definitely higher than 4.3", and had probably come up around a foot after we launched at about 11 a.m.

[mgood]

My experience has been that the Tot gauge has been reading lower that it actually is for close to 1.5 years. This is a welcome surprise every time I get paddle there, but could be a real problem for the inexperienced (or swimmers who flock there in the summer). I think that the higher it gets, the less the gauge is calibrated to the river.

For instance, I went once when the gauge said 3.4 and it felt more like 3.7. Another time, the gauge said 5.5 and it felt like 7 ft. I also recently ran Baker when the Tot was at 4.3(isn)- this is a different watershed and has occurred before, so take it with a grain of salt.

My point being that it's close, just not a precise as it used to be from my perspective.

[Hcarr999]

It may be off a little but the feeder creeks below the gauge were pumping tons of water in.

[tomOzarkVideo]

It may be off a little but the feeder creeks below the gauge were pumping tons of water in.

Yep.. we had about 3" of rain downstream from the gauge. There are 3 or 4 major feeder creeks down there. At around 1:30, the water rose about 2 FEET while we were standing at the machine.

[Cowper]

Yep.. we had about 3" of rain downstream from the gauge. There are 3 or 4 major feeder creeks down there. At around 1:30, the water rose about 2 FEET while we were standing at the machine.

I think this is the biggest factor in play here. On Saturday, when we returned to Ed Banks, we crossed Baker, which remained at a very low level even following the local rains we experienced. But Flat creek, which comes into the Cossatot at Ed Banks, normally something you don't even notice, was nearly matching the flow coming down the main river, thus doubling the total flow. So 4.x feet on the gauge didn't look anything like what we saw in the Falls. During the time Tom is talking about, when I went back to get in my boat after taking a peek at the Machine, 3 boats and a couple of paddles were about to float away from where their owners had left them, presumably on dry rocks a few minutes earlier. This was not reflected in any of the gauge readings upstream at Hwy 246.

With the gauge that far upstream, what we think the Falls looks like at 3.5', 4.0', or any other reference value is really only an "average" of what it looks like at that level. Some times it will be higher, sometimes lower, depending on how evenly the rain is distributed over the watershed, and depending on whether that is 3.5 and rising, or 3.5 and falling, or 3.5 and steady based on continued light rainfall. That said, shifts in the relationship between a given gauge height and cfs at that level do occur, but I don't know if one has occurred here or not. Folks from ArklaTex probably do get to the Tot more often than I do, and could easily spot a trend before I would. It would be really interesting to contact someone at USGS and see when the last time this gauge was calibrated for that and whether or not their saw a shift; USGS will do that every few years, and if we are convinced that something has occurred here they may want to work a calibration into their schedule so that any planning based on this gauge data will be as accurate as possible.

For me, I'm happy just knowing that at 3.0 feet, I'd still drive down there if it was a sunny warm weekend or a first timer's trip, 3.5 is always fun, somewhere around 4 "over the top" might be an option, and if it gets to 5.0 Eye Opener is going to eat somebody's lunch if they wander off line or don't paddle like they mean it.

[we66erno1]

Poppa Joe said it was 7.5

http://vimeo.com/97090042" onclick="window.open(this.href);return false;

Password: wwp

[JGoodwin]

Heath and I guessed we were just below 6' after running the falls. I still was able to run a semi-traditional line at the machine but the mix in the bottom looked wild! Haven't run an old school long boat in about 3 years so I was pleasantly suprised not to contribute a roll to the video.

[hilbili]

Factor in the recent clearcuts.

[hilbili]

Anybody have access to a thedolite so some reference like the longpool gauge ciuld be placed?

[hilbili]

Anybody have access to a theodolite so some reference like the longpool gauge ciuld be placed?

[sig]

It's a usgs gage... It's tied in to the real world just fine. The datum appears to be 786.00 NAVD88.

Gage's are adjusted periodically and that can change the gage height reading. The channel changes over time and that changes things as well.

It looks like the USGS last developed/published a rating curve for the Tot in January 2014.

The gage will never reflect water coming in from tributaries located downstream of Hwy 246. So if there has been lots of clear cutting in those drainage then you can expect more water to make it to the river.



Edited to add...

FWIW, four feet on the (falling if you think it matters) gage this weekend corresponded to 464 cfs.

And four feet on the (falling) gage on (randomly picked) 13 Mar 2012 corresponds to 464 cfs.

This relationship also holds true on 08 Oct 2008.

So it looks to me that if you feel the gage isn't agreeing with the amount of water you are seeing at the falls then something has changed in the watershed below the gauge.

[hilbili]

Anybody have access to a theodolite so some reference like the longpool gauge ciuld be placed?

. At the falls.

[Cowper]

Do we really need another gauge on the Tot? We've got the 246 gauge; another stick gauge at the Visitor Center. We've got the Cannonball rock. Someone could paint a few numbers on the steps at the Falls put in if desired, or just code the steps with green for enough, yellow for getting high, red for danger zone, etc.

If someone is going to put effort into installing another gauge, I think a stick gauge on the crossing over Baker Creek would be far more valuable in closing some information gaps. Park Rangers could probably get in the habit of noting a reading when they drive across, and we could count on the Baker Creek gate being unlocked when we needed it most once we gave them some "trigger points" for levels at which we would want to float it. They try to do it for us already, but the whole point of this discussion is that the flow in tributaries does not always match what we see at Hwy 246, so sometimes Baker is floatable when the gate is still locked.

[mgood]

Yes! A baker gauge! Now you're talking. As an aside, I think that my personal minimum level for baker is much lower than the traditional one(5.0 ft on the tot gauge, over the slab on the side of the baker takeout). I had an enjoyable run about two months ago, with low water but still quite enough, when the water at the takeout was about two or three inches below the "minimum" slab. Something to keep in mind- we could get a better idea of just how low is too low if the rangers just permanently left the gate open. What is the purpose of closing the gate anyway? It always seemed to me to be more of a hindrance than anything else.

And I know that tributaries and spotted rainfall will vary the level at the falls- I remember one occasion when baker ran and the tot didn't. But I still think the gauge is reading lower than actual/traditional. I'd like to think that I have a good feel for guessing the river level at the tot-, and based on my memory the 3.5 of the last year and a half has been much higher than in years past. Just personal observation based 10 or so runs. This is a GREAT problem to have.

[sig]

Food for thought... The Tot gage has a contributing drainage area of 89 sq mi.

At the Tot Falls, the drainage area grows by 40 sq mi to 129 sq mi. That's a 45% increase...

Or stated another way, 40 square miles that aren't represented by flow at the gage.

I bet your feeling on "gage reading vs what's actually at the falls" is correct. I think it has more to do with changes in the lower 40 sq mi rather than problems with the gage itself since we've shown that the stage/discharge relationship hasn't changed in a couple of years. Questions to the USGS may reveal when they last calibrated the gage and the rating curve.