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Current Theme: Watershed
South Boulder Creek Information

Flood Data
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Watershed Address: 
South Boulder Creek, Boulder Creek, St. Vrain, South Platte, Platte, Missouri, Mississippi, Gulf of Mexico 

Approximate length: 37 miles

Description: Beginning along the Continental Divide from James Peak to near Corona Pass, the South Boulder Creek drainage drains some 30% of the entire Boulder Creek Watershed. From the Moffit Tunnel, where the Denver Water Department brings water through from the Western Slope, to Gross Reservoir, where Denver stores some of its drinking water supply, South Boulder Creek serves as a channel for moving water from one basin to another.

Below Gross Reservoir South Boulder Creek cuts through what is now Eldorado Canyon State Park and then passes through the town of Eldorado Springs. Here a series of diversion ditches begin, including the Community Ditch that provides drinking water to communities to the east.

As South Boulder Creek swings north through the small town of Marshall (which during its boom as a coal mining town was once larger than Boulder), it passes by an old gravel mining operation that was sold to the Board of Regents to the University of Colorado. CU plans to develop the property, perhaps for a new stadium, but the issue is complicated and controversial due to the fact that it lies in the floodplain of the creek and existing floodplain maps are inaccurate.

By the time South Boulder Creek joins Boulder Creek north of Valmont and east of 55th Street, much of its flow has been diverted for irrigation or to be used by the Public Service Company's Valmont Power Plant near 63rd and Arapahoe.

Be sure to see photos of 1938 flash flood in Eldorado Springs in BASIN Gallery and read accounts of the flood in 1938 from History of Flash Floods in BASIN History.

Also see Beyond BASIN: South Boulder Creek Management Area and Boulder Creek Watershed Website


  • Rollinsville
  • Eldorado Springs
  • Majestic Heights
  • Keewaydin
  • Cherryvale
  • Fairview High
  • Majestic Heights Elementary
  • New Vista High
  • Burbank Middle
  • Platte Elementary
Flash Flood Data  
Source: FEMA (Federal Emergency Management Association) June 2, 1995 Flood Insurance Report
Flooding Source & Location
Drainage Area (Square Miles)
(Cubic Ft.
per Second)
Confluence w/ Boulder Creek 

Note: A representative of FEMA has called for a new survey of the South Boulder Creek floodplain due to the the need to revisit floodplain mapping because of flawed surveys in the past.


Historic Flow Data From USGS:
South Boulder Creek at Rollinsville

South Boulder Creek at Pinecliffe
South Boulder Creek at Eldorado Springs

It is our intent to build a comprehensive information resource based on the local watershed theme. One way you can help us develop this area of the BASIN WWW site is to take this quick survey. Your input is greatly appreciated.

Do you have a comment or question about this area ? Select here for a more general BASIN feedback form.

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Last Page Update - Tuesday December 27, 2005