John Rosenberg’s recent editorial citing reasons for replacing Capitol Lake with an estuary provides an opportunity to present a factual version of this issue – one that identifies the lake as a priceless asset that should be retained and maintained.
Rosenberg presents the New Zealand Mud Snail as though it is a real issue. It is not. The NZMS can survive in the salt water of estuaries, as it does in the Columbia River and elsewhere. It will not be eradicated if the lake is replaced by a mud flat.
The Olympic mud minnow and two species of native freshwater mussels, however, now living in the Lake, are another story. Those organisms, including one state-listed “sensitive species,” would be lost if the lake were destroyed.
Another supposed ecological benefit of a restored estuary, recovery of a salmon run supposedly lost when the dam was built, is a myth. There was never a run of native salmon in the Deschutes River. Tumwater Falls blocked their passage and would do so again, if a natural estuary replaces the lake. Remember it was humans who built the fish ladder when the tide lock was constructed.
Rosenberg cites “peer reviewed science” as supporting the idea that the Lake harms Puget Sound. This is misleading. According to a recent peer-reviewed Department of Ecology document (the “TMDL Report”) that “harm,” as calculated by a computer, is a lowering of dissolved oxygen levels in Budd Inlet during the summer.
That “harm” is shown by DOE’s own report to be immeasurably small and affecting only 6 percent of Budd Inlet (near the LOTT Plant and Moxlie Creek). The other 94 percent of Budd Inlet is completely unaffected. Budd Inlet actually has good dissolved oxygen levels when compared to Eld Inlet, (no dam or lake) where dissolved oxygen levels occasionally fall to low levels that actually kill shellfish – something we do not see in Budd Inlet.
One undeniable fact is that the plants in Capitol Lake remove some 20-30 tons of nutrient nitrogen from the Deschutes River’s water every summer. This nutrient load would enter Budd Inlet directly, if the lake were replaced by an estuary, reducing the Inlet’s oxygen.
What happens next is a good question. Either the lake plants release the trapped nitrogen later in the fall when they decay or they do so in summer when the released nitrogen (and the direct oxygen reduction from the decay itself) can damage Budd Inlet. Whatever the answer, a maintenance program of dredging and removal of lake vegetation every summer would easily head off any real or potential problem. It would also improve the appearance of the lake.
If a mud flat were to replace the lake, direct physical removal of plants taking up the nitrogen would be impossible. In addition, Rosenberg fails to mention the flood control benefits of the tide lock which has helped to prevent flooding in downtown Olympia. As we prepare for sea-level rise, it is important that we retain the tide lock as a method to protect the North Capitol Campus and downtown.
In addition to losing the environmental services of Capitol Lake, the economic cost of reconstructing a mud flat would be about a $258 million dollars compared to $40 million for the lake over the same period. As a community, we should of course pay such costs when they result in positive improvements to our region and state – but in this case the less expensive lake option is by far the better choice.
It is important to understand that dredging has been delayed for decades because the Legislature has failed to appropriate funds to maintain this important part of the Capitol Campus. It is now time for the Legislature, in partnership with the Port of Olympia, Thurston County, the Cities of Olympia and Tumwater and the private sector, who benefit from dredging the lake, to reinstitute regular maintenance.
Although Rosenberg says that making the lake or mud flat choice is “difficult,” it is actually an easy choice. Most of the Washington public wants Capitol Lake to be maintained as it can be – a beautiful body of water mirroring the beauty of our state Capitol, serving as a popular park-like connection between the State Capitol Campus and downtown Olympia, and performing ecological functions that protect wildlife and Puget Sound.
It is far less expensive, ecologically sensitive, and in accordance with the public’s vision to move forward with the lake’s preservation with dredging and other deferred maintenance.