In October 2009, a cold spell and strong winds cooled the warmer, more highly oxygenated water on the surface of the Upper Oso Reservoir in Rancho Santa Margarita, CA. The cooled water sunk to the bottom, bringing less-oxygenated water to the top. The “flip” produced an algae bloom and led to the release of hydrogen sulfide gas and a rotten egg-like stench that lasted for three weeks and affected residents for miles

Schuler Engineering was contracted by Santa Margarita Water District to install a proprietary oxygenation system designed by ECO2, Inc.  The oxygenation system incorporates a stainless steel cone and appurtenant equipment to be used to ensure the lake’s oxygenation levels remain high enough to prevent the reservoir from emitting a sulfurous smell.  Schuler Engineering installed the 18-foot-tall cone about 60 feet underwater at the bottom of the reservoir. The new equipment will help keep water near the bottom of the reservoir highly oxygenated. That water will then mix with water that has low levels of oxygen to prevent another algae bloom from reoccurring when the weather begins to cool down in the fall months.