LAKES OXYGEN SATURATION

by Zach Hache, Water Resource Manager

One of the most important parameters that Lake Managers pay attention to in a water-body is the oxygen saturation. Dissolved oxygen in the water column is important for maintaining a healthy lake and mitigating issues with the fishery, odor production, and nutrient cycling from the lake sediment layer. Oxygen is naturally dissolved into the water column at the surface of a water-body through diffusion from the atmosphere. Additionally, aquatic plants and algae can introduce oxygen to the water column through photosynthesis.

During the summer months, the amount of oxygen in the water column naturally drops as the potential oxygen saturation decreases as temperature increases. At the extreme temperatures we have in the valley, the water column may only be able to reach 60% of the oxygen saturation when compared to our cool weather months. Additionally, higher temperatures in the upper water column can prevent the natural cycling of dissolved oxygen at the surface from reaching the lower depths of the lake. This disruption in the water column is known as a thermocline. Oxygen levels below a thermocline reaches a level below 4.0mg/L as DO, there is no longer enough oxygen in the water column to support the fishery and fish losses would be expected.

In-lake aeration systems are commonly used to disrupt the thermocline, lifting colder water from the bottom of the lake to the surface allowing for oxygen addition from the atmosphere before falling back to the lower levels of the lake.

Previous diurnal aeration studies have been completed at Dobson Ranch in the past and they did not indicate the need for bottom aeration in all of the lakes at that time.

Next Water & Lake Management Committee Meeting La Casita Recreation Center - Grande Room

TUESDAY, AUGUST 13 at 5:30 p.m Meets on the second Tuesday of every month.