Technical Report No. 14

SWINOMISH CHANNEL AND PADILLA BAY: SURFACE CURRENTS DURING FLOOD TIDE AND WATER QUALITY

Douglas A. Bulthuis and Anne M. Conrad

October 1995
Bibliographic Citation
Bulthuis, Douglas A. and Anne M. Conrad. 1995. Swinomish Channel and Padilla Bay: surface currents during flood tide and water quality. Washington State Department of Ecology (Publication No. SWR-R-95-88), Padilla Bay National Estuarine Research Reserve Technical Report No. 14, Mount Vernon, Washington. 99 pp.

Abstract
Water quality (total and volatile suspended solids, total coliform and fecal coliform bacteria, nitrate, nitrite, ammonium, soluble reactive phosphate, total dissolved phosphate, salinity and temperature) was measured in the Swinomish Channel near the entrance to Padilla Bay. Samples for analyses were collected hourly for twenty-eight hours, weekly for eight weeks and monthly for fifteen months near the time of low water slack tide. Surface currents during flooding tide were measured with drift sticks on four dates. Tidal currents and water height did not coincide at the Swinomish Channel entrance to Padilla Bay. North flowing currents predominated. Strong seasonal patterns were not evident for any of the water quality parameters except for temperature and nitrate, which was higher (15-25 μg-at of N/L) during December - April than during the rest of the year (4- 15 μg-at of N/L). The concentrations of fecal coliform bacteria exceeded the Washington State standards for Class A marine water. The predominate movement of Swinomish Channel water in Padilla Bay is north and south with little movement of surface currents into the rest of Padilla Bay.