The start-up costs of the project were funded through the American Recovery and Reinvestment Act channeled through OWRB. COMCD pays for the oxygen and does maintenance on the system.
At this time, there is one treatment area by the dam, where the lake is deepest. By treating this problem area, the whole lake benefits, but this area is key because it’s also the location of the raw water intake for the lake’s municipal customers.
An original goal of the SDOX system was to increase dissolved oxygen in the lower strata of the lake without mixing upward. If mixing occurs, some of the oxygen is lost upward, instead of staying in the lower lake level where it’s needed most.
A secondary goal is to reduce the sediment phosphorous to prevent algae bloom and to reduce the total organic carbon in the lake.
A long-term goal is to lower drinking water costs and reduce taste and odor complaints by water consumers.
During the first two years, the program showed some success, but mixing of the layers occurred. However, the lake’s oxygen increased and broke the trend of rising levels of chlorophyll-a. Monitoring chlorophyll levels is a way to track algal growth.
BlueInGreen made some adjustments and solved the mixing problem. Even though the SDOX system was off during a portion of July for repairs, once it was operational, the improved oxygen levels quickly returned.
“It’s going to take us a while to lower that sediment oxygen demand,” Cadenhead said.
Compared to 2007, which was a similar year with a lot of inflow from rain, calculations showed the difference in oxygen levels this year as strongly improved.
The areas of anoxia (lack of oxygen) in the deep parts of the lake were the lowest ever calculated by OWRB.