There will likely be a lot of talk about the work of Dr. David Milne about water quality and the Deschutes Estuary. You can read Milne’s entire work here, but you would be better served taking a look at the original work by the Department of Ecology here. Milne tries to refute years of scientific research and examination by Ecology staff, but he ends up ignoring a major reason for low water quality in Budd Inlet.
This poster that Ecology put together for the Salish Sea Conference does a good job of explaining exactly how Capitol Lake is the cause of water quality problems in Budd Inlet. The poster undercuts his main thesis that the presence of the lake increases the amount of dissolved oxygen in Budd Inlet compared to an estuary.
Dr. Milne was correct that the Lake condition allows less nitrogen to enter the Inlet; however, he completely ignores the issue where the increase in carbon from a lake condition decreases dissolved oxygen. Comparing the two scenarios where “lake = less nitrogen” versus “lake = more carbon” output shows that there is lower D.O. from the lake’s carbon.
Where does all this carbon come from? We’re all familiar with the large green mats of algae that grow in Capitol Lake during the summer. All of these algae mats eventually die off. And, when they do, they release large amounts of carbon that drive down the dissolved oxygen in Budd Inlet.
There are some very strong statements presented in the poster.
“The effects of Capitol Lake dam, even with only natural nutrient loads, also do not meet DO standards in Budd Inlet.”
“Both the magnitude and extent of DO standard violations are higher with the lake in place compared with if the lake is converted into an estuary.”
“The dam alone causes a DO depletion of about 2 mg/L.”
“Decreased DO in the critical areas of East Bay in Budd Inlet is due to increased residence time due to discharge at Capitol Lake dam which tends to “trap” the water in East Bay.”