SAN JUAN COUNTY CONSERVATION DISTRICT

Water quality improved by Conservation District efforts

posted 07/12/2006
San Juan County Conservation District (SJCCD) recently completed a three-year effort to improve water quality in the Port Stanley Lagoon on Lopez Island. Installation of a new, hydraulically-operated tide gate at the lagoon outlet in June restored daily tidal flow into the lagoon for the first time since the early 1960s. With the completion of the project, SJCCCD and its project partner the San Juan County Department of Public Works (DPW) expect to see not only improvement in the lagoon water quality but also improved habitat for fish and wildlife and reduction in flooding during severe winter storms.

Ever since a tide gate was installed to block tidal flow into the lagoon outlet in the 1960s, the lagoon gradually filled with sediment so that it became so shallow that only a stagnant puddle remained by late summer. In addition, without continuous tidal flushing, the tide gate's outfall pipe on the beach sometimes filled with sand, preventing winter storm runoff from draining properly.

At the request of the lagoon owners, the Mattson Family, SJCCD received a US Fish and Wildlife Service grant in 2003 to complete an engineering study to evaluate ways to restore some degree of tidal exchange while improving the winter drainage and flooding situation. After completing a hydraulic modeling study and field testing, SJCCD presented several options to local community members. The Mattsons and other neighbors favored a plan to allow partial tidal exchange into the lagoon, but only up to a level that would not impact lawns, drain fields, and other property.

SJCCD next won a grant from the Washington Department of Fish and Wildlife to design and implement this plan. The plan's first task included dredging the outlet channel and modifying the beach outfall pipe, which were completed in August 2005. The second task involved fabricating and installing a new type of tide gate that would open and close at pre-set tidal elevations. This type of tide gate, which is only the third installation of its kind in Washington State, works like a screen door. The force of water draining from the lagoon on a falling tide opens the "door." The resistance in the door's hydraulic piston keeps it open as salt water flows back into the lagoon on the next rising tide. When the tide reaches a specified height, it trips a float valve, which releases the pressure in the piston and allows the door to close again.

DPW's Lopez Island road crew installed the new tide gate in June 2006 and continues to work with SJCCD and our design consultant to adjust its operation. A typical question from curious local residents is "where is the power supply?" The answer is "it's run by the tides, so the power supply is the moon." The tide gate can be viewed inside a grated vault along Port Stanley Road.

"It was great that the Mattsons, their neighbors, and the county agencies could work together to restore tidal flow to the Port Stanley pond," said Lopez Councilman Bob Myhr. "This lagoon is significant habitat for both migratory birds and feed fish, and it can now be enhanced even further with the new tide gate in place." Myhr noted that special thanks goes to the state fish and wildlife service, the county public works department, and the San Juan County Conservation District for this ongoing project.

For more information about the project, contact Ron Zee, SJCCD District Manager, at email ronzee@rockisland.com or (360) 378-6621.

SAN JUAN ISLANDER © 2008

news@sanjuanislander.com

ABOUT US | ADVERTISING INFO | CONTACT INFORMATION |