USGS Gauge

[ollie]

Ok, having a little trouble reading the Elk on the gauge. Total CFS has risen just about 100 cfs over the past week, but the three main creeks that feed this river are all going down in total cfs. Since there are no major springs feeding the Elk how can the river rise when the feeder creeks are falling in discharge? Doesn't make sense to me. Possible error on the gauge reading?

[MOPanfisher]

I haven't looked at the gauges for the Elk, but it is not uncommon especially after some big rains/floods that the gauge has issues and must be re-calibrated or repaired by USGS folks.

[Greasy B]

Or a localized storm effected a tributary between the gage your reading and the gages up stream.

[MOPanfisher]

I did take a quick look at the gauge, it doesn't look like a storm event, a fairly steady slow increase, strange. Further upstream it is falling.

[moguy1973]

Might be that the water that is in the tribs is finally making it down to the Elk gauge?

[ollie]

No local rain between gauge and upstream as well as the water in the tribs finally making there way downstream. Since the gauge is almost to Grand Lake I wonder if that has more impact on it? As in they are not pulling water as fast as they were when all the flooding took place? It just is very odd to still see that gauge reading that high at this time of the year.

[moguy1973]

Or maybe they are pulling more water since the flow is higher?

[Guest]

could be waste water discharge, who knows

[Al Agnew]

How high is Grand Lake? Like you said, the gauge is only a few miles above Grand when it's at normal level. Looks to me like a rise of only a few feet above normal would back water up to where the gauge is. If Grand is high and still rising slowly and steadily, that's probably what you're seeing at the gauge.

[Kelroy]

Right now, the Grand is at 743, but it needs to be in the 750's before the Elk gage is affected by backwater conditions.

http://ok.water.usgs.gov/projects/webmap/grandlake/

There is the possibility of discrete recharge through vadose or groundwater seepage (vs surface recharge through visible springs) but I am not familiar enough with the local groundwater situation to say that is the case with any certainty.

Scrolling back through the data, I see that it was measured on Aug 5 @‌ 1744hrs, GHt of 4.16 and measured flow of 422cfs. There is also a gap in the data, about 2hrs15min, preceding the measurement. Normally there is not a significant data gap unless the DCP fails to transmit, obvious invalid data is blocked from display, or major equipment is being repaired or replaced in conjunction with a site visit. It is possible that something needed service, with a routine check measurement following.

 Since it is an OK district gage, I don't know if they are running a bubbler, radar, or nitrogen system there. If it is an air or nitrogen system, it is possible that the readings are the result of problems within the system, perhaps an air pressure leak or fouling of the orifice line. However, in my experience, such problems tend to produce either very erratic data shifts, distinct 'stair-step' errors, or intermittent gaps where erroneous data spikes are automatically suppressed when they exceed normal thresholds.

Since this rise seems to be fairly smooth and consistent (and only 3/10ths of a foot over 9 days) I would be inclined to think that the gage is operating normally, and what we are seeing is some discrete recharge, but that is merely a hunch.