ARWA Update

The rain we are receiving today has already arrested the declining river flows at the upstream gauges and should cause the flows to increase if it continues long enough.

Earlier this Summer we experienced a problem with taste/odor in our finished water followed shortly thereafter with a discolored water event. The taste and odor issue was caused by our response to a sudden increase in algae in the reservoir. We treated closer to the intakes than we normally do and we learned to monitor algae more frequently to catch future increases sooner so we can treat farther away from the intakes with less algaecide.

The discolored water was caused by manganese, which occurs naturally in the raw water and rises following a rain event. We conducted a study of alternative filter media in 2009 and 2010 to determine if it would remove manganese better than our current media. The results of that study show that we do not normally have enough manganese in our raw water to condition that media so it will work better than our current media when we have a manganese spike following a rain event. The consultant recommended some alternatives and we are working on a request for proposals to investigate one of those alternatives, in-reservoir aeration near our intakes. This alternative will take some time to implement. We are proceeding, however, with investigating two other alternatives to increase the number of barriers our treatment process will provide to reduce the manganese levels in our finished water. The first is to feed an oxidizing agent we already use at a second location during a manganese event. The other is an investigation of alternative corrosion control agents to deal with any manganese that reaches that stage of our treatment process. We will keep you posted on the results of all of these investigations.