Algae plume control

[Barry Moore]

We have several micropools that have algae plumes cropping up during the summer.  All are the 2.5' depth and have subdivision drainage discharge to them.  I suspect that it is homeowner fertilization coupled with the depth that is causing this.  The homeowners are complaining of the smell.  Is there a way to control the algae?

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Barry O. Moore, PE

Vice President      Project Manager

7006 S. Alton Way, Bldg. F   Centennial, CO 80112
Office: 303-694-1520                  Fax: 303-694-1617
www.emkc.com                 EMK map link

[Holly Piza]

Algae control in stormwater facilities is difficult because of the nutrient loading.  We experimented with barley bags in a constructed wetland this summer and will continue to look at this practice for inhibiting algae growth in retention ponds and constructed wetland ponds.  Micropools are different because they are going to have such concentrated levels of nutrients.  I don’t see it as a design issue - the micropool is intended to trap nutrients.  Have they always had algae here or is it just time to muck out the micropool?  The best way to get rid of it is mechanically harvesting it although given the right setting, algae can come back in a matter of weeks.  If it’s been four or more years since the micropool was mucked out, it’s lost a good portion of its depth.  I would recommend mucking it out.

 

Good luck.     

 

Holly Piza, PE, CFM

Project Engineer

Master Planning Program

Urban Drainage and Flood Control District

West 26th Avenue, Suite 156-B

Denver, CO 80211

303.455.6277

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[Ben-UWLLC]

Use of barley bales/bags have been shown to help with algae blooms (original findings came from Europe) apparently due to natural algaecide in barley cuttings; however, limited data also show that is done at the sacrifice in the reductions in nutrients.  This makes sense since the nutrients being taken up by algae are no longer seeing this demand.  More research is needed on this phenomenon.  In the meantime, if nutrient control is not of the main concern, this is an apparently good way to reduce algae blooms in ponds and constructed wetlands.   As to micro-pools, Holly makes very good points and I have nothing to add to her comments.  

 

Ben Urbonas, P.E., D.WRE

Urban Watersheds, LLC

303-765-0155 (O & F)

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[Bill Ruzzo]

I would also like to point out, which should be obvious in the responses, that algae in a detention pond is an indication that they are working.

 

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