Increased sedimentation threatens ecosystem

Increased sedimentation threatens ecosystem

Posted: Nov 28, 2009 1:36 PM Updated: Nov 28, 2009 5:04 PM

by Heather Hauswirth

Constructing a berthing for a nuclear transient aircraft carrier pier slated for either Apra Harbor or the shipping repair facility near Polaris Point does not come without significant environmental consequences. Dredging and other construction related activities increases sedimentation levels in the water.

Manny Duenas said, "Apra Harbor is a major lagoon for Guam and lagoons are normally good places for breeding grounds for fish and marine life and with the sediment that will be coming from Apra Harbor, I don't know how you can mitigate fine particles and the turbidity issue. It will affect Guam in itself because we know the fish don't just live in one area." The Fisherman's Co-Op president said biologists agree that the most acceptable paradigm for the natural environment is one where sedimentation is kept to a minimum.

Guam EPA Environmental Monitoring and Analytical Services Administrator Jesse Cruz says it is disruptive to the overall marine environment, saying, "During the dredging process, the sedimentation that could result from dredging has an impact on mainly the corals and the coral reef area where the fine sediments that will be released during the dredging process could be distributed through the larger area with the currents and settle down on top of the coral, which could cause a smothering affect of the corals."

A smothering of the corals would diminish their survivor ship in the area as sedimentation shades out the sunlight, which corals need for survival. Despite strict protocol in place for dredging, the Joint Guam Program Office's asst environmental director on Guam, Randel Sablan says there is no way to avoid it, but there may be a way to mitigate the impact.

He said, "On the compensatory side - what do we do with the coral that were impacted? Well, the army corps permit that the navy needs to obtain in order to do the dredging will require compensatory mitigation and in the DEIS there are four types of compensatory mitigation proposed."

These options include building an artificial reef to replace the services and functions lost, doing water shed enhancements to reduce erosion that impacts coral reefs, coastal mitigation proposals such as increasing waste water treatment, and a mitigation banking program where the Navy would outsource mitigation projects to a third-party.

But Cruz pointed out that isolating construction and dredging as much as possible is actually what's key to mitigation, saying, "Silk curtains or silk screens during the operations to minimize the fines from the area of the dredging, keep the dredging area to as minimal space as possible."

The debate continues about the best way to approach mitigation. As time goes on, fishermen like Duenas say they won't pipe down as long as there are fish that are going to be impacted by dirtier water. "Any fish in Apra Harbor part of the reproductive stage or part of the replenishing of this islands resource that will be removed," he said.

Duenas continued, "I saw the map for dredging of Apra Harbor and they are going to come right down the middle. That is a whole reef area that they are going to impact.

"And that's really sad."