Environmental Assessment and Policy

South Platte River - Cherry Creek Confluence

Sample sites at the confluence include one location in the South Platte and one in Cherry Creek immediately upstream of the confluence. Based on this guidance, DEH will post an advisory when E. coli levels exceed 235 colony forming units (cfu)/100ml. E. coli in the South Platte at the Confluence exceeded the advisory level 10% of the times sampled from May through September, 2007. E. coli levels in Cherry Creek at the confluence exceeded the advisory level 48% of the times sampled during the same period.

MOST RECENT BACTERIA SAMPLING S Platte & Cherry Creek Confluence Bacteria Results

Bacteria monitoring at Sloans Lake includes sampling at four sites: near the boat dock, the boat ramp, the middle of Sloans Lake, and the middle of the “Cooper” bay (east end) near the slalom course. There was an exceedance of the advisory level from all four sites on one sampling day during the 2007 monitoring season (21 sample events). Follow-up sampling indicated there was no need for a closure to recreational use of the lake. Based on three years of intensive sampling, there have been one to two sample events per year that would have warranted advisories. The elevated bacteria levels were typically triggered by a heavy rainfall or significant disturbances within the lake during the warmest part of the year (July-August).  

MOST RECENT BACTERIA SAMPLING Sloans Lake Bacteria Results

 

 

A portion of Bear Creek runs through Denver entering from Lakewood at Wadsworth Boulevard and continues east approximately two miles to it's confluence with the South Platte River.  Bacteria monitoring at Bear Creek currently includes sampling at one location in Bear Creek Park.   This sample site was added to the other weekly monitored locations (Cherry Creek-South Platte Confluence and Sloans Lake) in August, 2007.   

MOST RECENT SAMPLE Bear Creek Bacteria Results

What is Denver’s DEH Doing About Bacteria?

DEH has addressed the risk posed by elevated bacteria levels through:

DEH monitors the confluence and Sloans Lake more intensively because of the elevated risk posed by the increased recreational activity at these sites. There has also been targeted sampling within the watershed to identify significant bacteria sources. Results of this monitoring help the Public Works Department prioritize infrastructure improvements throughout the City.

The DEH in concert with the City and County of Denver’s Parks and Recreation and Public Works Departments developed informative signs that are posted at the confluence and Sloans Lake. These signs provide information regarding many aspects of the City’s water resources and also enlighten readers on the subject of hazards posed by surface waters with an emphasis on bacteria.  When monitoring results indicate bacteria levels in exceedance of advisory levels (Colorado Department of Public Health & Environment’s Natural Swim Areas Guidance, Section 4.6, p20), the water quality caution diamond on the signs will be replaced with a warning advisory.

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