Two tidal flow pipes with 2.5m in diameter were constructed in March 1998 for the fishery promotion investigation between north side of Honjo area and Hokubushosuiro.
Water quality of interchanging water of the pipes was investigated on June 6, July 10, and September 4 in 1998. The behavior of the inflow water in Honjo area was also investigated by using the drift buoys on September 4. Concentrations of salinity, total inorganic carbon, and water temperature were different between inflow and outflow waters. Then it was considered that different water-mass was interchanged through the pipes. However, nutrient concentrations were scarcely different.
The drift buoys were moved narrow area, which was about 100m from the pipes during inflow period. Then, it was concluded that the inflow water through the pipes were influenced only limted area near constructed pipes and was scarcely influenced whole water quality of Honjo area.