FLOOD02473

• County: Weld
• County: Logan
• Basin: South Platte
• Title: A Post Evaluation of Rainfall Reports Associated with Pawnee Creek Flood of July 29-30, 1997 in Eastern Weld and Western Logan Countie in Northeastern Colorado
• Date: 8/1/1998
• Prepared For: Weld County/Logan County
• Prepared By: CSU
• Floodplain - Doc Type: Flood Documentation Report

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without electricity, and Mrs. Artzer was immobile at the time, due to a very recent hip
replacement. However, they recall watching the rising flood waters illuminated by
frequent lightning. They have two rain gauges near their house that they read regularly.
Mr. Artzer considered going out to check them during the stonn, but the water was too
high. When he checked the next day, they were both full to a depth of about six inches
and overflowing. The Artzers have a long history of reading and recording daily rainfall
and were disappointed to have missed that measurement. The following day, as he
recalled (July 31), he went up to a stock tank on the hill about one mile north of their
house. It had been empty, but was full to a depth of 14" when he measured it. He
credited all that rain to the storm, but he also noted that about 1 112" had fallen the
previous evening (July 28).

The location of the stock tank was T 9N R 57W in the extreme SE comer of Sec. 16. As
I visited and photographed the stock tank, I found it totally open and exposed on the top
of the hill overlooking the Pawnee Creek valley to the south - beautiful remote setting, It
had just rained 112" before I arrived July 29, 1998 (based on Mr. Artzer's gauges) so I
tried to measure it in the tank. I noted a very uneven concrete bottom with depth
measurements varying from 0 to more than 2 inches depending on the location in the tank.

In summary, there is considerable evidence of extreme rainfall near the Artzer's home
during the evening of July 29th. Mr. Artzer's estimate of 14" was not unreasonable but
could have varied depending on exactly where in the uneven-bottomed tank he took his
measurement. Also, the rain from the previous evening and, in fact, from other rains in
late July, were likely included to some extent in the measurement. In my estimation,
taking the stock tank's unevenness into account and the rain that had fallen the
previous night, plus any evaporation that may have occurred, an estimate of 12"
would have been more reasonable with "B" confidence,

Guy Whitlock

T ION R 56W Sec. 20 SW
Original rain report: 12" in 5-gallon bucket

He and his wife were not at home for the storm. They had left on the 28th for Wyoming.
No measurements were taken at their home on Highway 71. However, when they
returned soon after the storm, they found 12 inches of water in what he described as a
straight-sided 5-gallon bucket on their land approximately two miles east of their house
(see location above).

There was no easy way to evaluate this measurement, as the bucket was no longer there
and no one lives at the site. Without a doubt, very heavy rain fell at this location along
Spring Creek. However, there are two concerns that must be considered with this report,
First, it appeared from the timing of the Whitlock's trip to Wyoming, that the bucket was
probably placed there before the rain began on the evening of the 28th, Based on nearby
reports one-half mile away (Virgil Johnson), 1.5 inches fell late on the 28th and would
have still been in the bucket along with the later rain. Secondly, there is the question of
whether the bucket was truly straight sided. For the most common shapes of 5-gallon

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