The federal criterion for determining “safe” bacteria levels is based on studies conducted on large bodies of fresh water—Lake Erie at Presque Isle State Park near Erie, Pa. (above), and Keystone Lake near Tulsa, Okla. (right)—not on urban streams or creeks. Photos: Presque Isle State Park, Oklahoma Tourism and Recreation Department, and PBS&J
Houston's White Oak Bayou flood-control channel must meet the same stringent standard as that developed for beaches at recreational lakes.
Back to the Bayous
Most of the time, the flows in Buffalo Bayou and White Oak Bayou, urban streams in the western portion of the Houston metropolitan area, consist of treated waste-water effluent. While many people use the trails along these bayous for biking and jogging, few swim in these waters.
Following the “fishable-swimmable” goal of the Clean Water Act, the Texas Commission on Environmental Quality designated the bayous for head immersion swimming, which requires the water to attain the criterion of 126 colonies per 100 milliliters of fresh water. Due to various factors, the bayous exceed this acceptable bacteria level. After concluding that stormwater conveyance systems were a major source of the bacteria, the commission proposed that stormwater dischargers reduce loads by 100% as part of its bacteria TMDL for these waters.
At press time, the commission was revising that recommendation based in part on comments from local utility managers. Although committed to improving water quality in the bayous, they were concerned about the appropriateness of the underlying surface water quality standard and the feasibility of implementing the large bacteria discharge reduction requirements.
In comments submitted to the commission in March 2007, Houston's Department of Public Works and Engineering pointed out that E. coli only indicates the presence of fecal contamination, and that the organism doesn't directly measure the presence of pathogens. The department noted that the “science, existing technology, economic feasibility, and social acceptability of potential measures [to reduce bacteria loads] need to be established.”
Harris County and Harris County Flood Control District managers expressed similar concerns and asked the commission to move forward with their planned review and revision of the applicable surface water quality standards to ensure that the applicable standards are appropriate. They suggested that swimming may not be an attainable or existing use in all portions of the bayous, pointing out that “streams in which full head immersion cannot occur because of low flow conditions are held to the same rigorous standards as a bathing beach.”
Finally, they pointed out that rather than directly indicating an actual human health risk from a microscopic pathogen, E. coli only indirectly indicates whether a stream's water threatens human health because it only indicates the possible presence of fecal matter from warm-blooded mammals, which may or may not contain human pathogens.
Like their colleagues nationwide, these managers want to move forward with actions to reduce bacteria loads from controllable sources, particularly those from human sources, and improve their communities' surface water quality. But they, like others around the country, would like instream standards to be examined and possibly refined on a concurrent path.
— Bloom is a stormwater compliance group manager in the Houston office of environmental consulting firm PBS&J.Web extra:
Bacteria is the second-leading cause of water body impairment nationwide. For more information, visit the "Article Links" page.
- Walking the Tightrope How to cope with discharge requirements that apply lake-specific criteria to streams and rivers.