FLOOD08176

• Designation Number: 24
• County: Boulder
• Community: Unincorporated Boulder County
• Stream Name: Upper Saint Vrain Creek
• Basin: South Platte
• Title: Floodplain Information Report - Upper Saint Vrain Creek - Volume IV
• Date: 6/1/1972
• Designation Date: 7/1/1993
• Floodplain - Doc Type: Floodplain Report/Masterplan

The people living ..
floodadout,endmeny
ground and safety.
town}.. .wcreina
deep."

. along the banks of the river were
abandoned their homes for higher
. . homes (in the lower part of
roaring Sea of water2and3 Teet

1.~a:i.!?~.7 - :>..:ring the nIght of 8 and 9 ~ay appro,"""otely
3t05inchesofrainfellovertheentirebaslnofSt.VrainCreek.
The rain beganaboot 10 p.m. and stopped about 6a.m. wlth5t. Vraln
Creek peak i ng at Lyons a bou t I ".m. On 9 '~ay at 3,060 c. f . s . The
flooddam"ged and destroyoo irrlgationdiversionworksandbridgos
downstream from Lyons.

AnothElrcreston the following day again flooded houses In
the lo"er areas of town and washed out 300 yards of railroad track
east of Lyons. The peak discharge On 30 July was later ccnputed to
be9,400c.+,s. TherlghtbenkofNorthSt.VralnCreekwesfloodOO
to a width of 300 feet.

I2_J~n~19.i1 M The I"rgest peak discharge of record On St.
Yraln Creek at Lyons Is 10,500 c.T.S. on 22 June 1941. ThIs flood
originated mostly on South St. Vrain Cr~k and the creek peaked very
rapidly with floodwaters receding quickly. It!sas5\Jmedth<ltan
extra-nelylocaTiZedCloodoorstoccurrOOCNerSouthSt.YralnCraek
"shortdistanceupstream from Lyons.

~:i~n! .:!..u~e_I2.52. - Heavy rainhll combined "ith sn"""""lt
runoflcausedprolongedhlghflo"sonSt.VralnCreek. Theworst
flooding occurred On 7 and 8 ~ay and from 15 to 2\ Juno. Roads and
bridges "long the stre<lm were extensively damaged, stream banks
were arooed, f<lrmlands were floo<led. The peak discharge at Lyons
W<lS 2,900 c.f.s. on 7 May. VarIous flood photogr<lphs are shown on
this and the foilowing pages.

l ~au~t_I2.51- Lyons roceived 6.3 inches of rain fran a
cloudt>Jrsttypestormthetbegallaboot6p.m.on3I'oJgust. This
canbined wIth genural heavy rains over the basin to causa flooding
from Lyons to the mouth of St. Vrain Creuk. Flood duration was
less than 12 hours. SeverediO'11agerasultedtotl1ehigl1wayalong
SouthSt.VrainCreek.lntheruralareasdownstreomfranLyons
~ucl1 shOCked grain was waShed from the fieldS.

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i.:!..u~e_I2:'I2. M The effe<;:ts of this tlOO<l were felt largely
downstre1lmofLyons. Prolongedrainfoll a.ndheavysno""",,litrunoff
kept St. Vraln Creek out of its banks in the rurel oreas during most
of the month of Juno and bridges, rO(lds, and irrig<ltlonheadworks
weredamag...J.

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Figure 9. St. ~rain Creck, MolY 9, 1957 ~ Overf 10" at south ond
01 Highwily7 bridgenellr Lyons.

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