Capitol Lake is healthy

July is when the giant natural water purification facility known as Capitol Lake goes into high gear. About 5 tons of nitrogen fertilizer were captured during June by the plants now showing on the lake’s surface, and will be held there until those plants die back in November. More will be captured all summer long. Those are tons that won’t be driving oxygen depletion in Budd Inlet this summer.

The plants make Capitol Lake look unsightly, which many folks confuse with “sick.” Not so. Capitol Lake has actually been clean enough to swim in for the last 15 years. It has high dissolved oxygen levels from surface to bottom — better than all other (monitored) Thurston County Lakes and (during the summer) southern Budd Inlet. During September 2013 (worst month of the year for Budd Inlet), a colleague and I went out on the lake, measured its dissolved oxygen, and saw those high levels for ourselves. (We also saw big Chinook salmon.)

Outstanding as it is, all by itself, Capitol Lake can be made even better. A floating plant harvest and removal operation could tidy up its appearance and permanently remove tons of nitrogen fertilizer from reaching Puget Sound.

When you see all of those (native) plants, realize that all of that growth would occur in Puget Sound in the form of phytoplankton — where it would decay and deplete oxygen — were it not for the lake. Helping the lake helps to save Puget Sound.

This story was originally published July 3, 2016 at 7:50 AM with the headline "Capitol Lake is healthy."