FLOOD10386 ‎(2)‎

• Designation Number: 576
• County: Gilpin
• Community: Black Hawk
• Stream Name: North Clear Creek, Gregory Gulch and Chase Gulch
• Title: Floodplain Information Report - Black Hawk
• Date: 7/1/2004
• Prepared For: Black Hawk and CWCB
• Prepared By: Love and Associates
• Floodplain - Doc Type: Floodplain Report/Masterplan

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15

500-year estimated only within City of Black Hawk
~~~S;ur.face t1ows~reduced~fOl:~10-,-50-,ando 100-yearoevents~by~bypass~pipe
3 Surface flows reduced for 10-,50-, and 100-year events by discharge to Main Street.
4 Surface flows reduced for 10-, 50-, and 100-year events by Gregory flume.
s Only 100-year flood peak: estimated for LOMR
See Catchment Area Map for Design Points

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LocationlDesign Flood Peak Discharge (cfs)
Point (DP) lO-year 50-year lOO-year 500-year1
North Clear Creek (NCC)
Confluence Clear 1200 3200 3700 not estimated
Ck. (DP NC)
City Boundary 670 1810 2370 4720
(DP NC1)
Jacobs Bypass 35 900 1420 4720
Pipe2
Confluence Greg. 670 1810 2370 4720
Gulch (DP NC2)
Confluence Chase 600 1630 2120 4270
Gulch (DP NC3)
Confluence Miss. 540 1480 1925 not estimated
Gulch (DP NC4)
DP NC5 350 1000 1310 not estimated
DP NC6 232 710 929 not estimated
Gregory Gulch
NCC to Main St.J 33 225 360 665
Gregory Flume 4 90 660 960 1590
(DP G1)
City Boundary 290 860 1160 1590
Dorothy Lee 120 440 550 not estimated
Reservoir Outlet
(DP G2)
Chase Gulch
NCC to City 175 430 550 2100
Boundary (DP C1)
Chase Gulch 100 295 380 not estimated
Reservoir Outlet
(DP C2)
Fourmile Gulch :l
Confluence NCC not not estimated 520 not estimated
(DP F1) estimated
Upstream of not not estimated 390 not estimated
Confluence estimated
(DP F2)

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Table 1

Updated Flood Peak Discharge Summary