Port of Stockton
2201 W Washington St.
Stockton, CA 95203
PH 209-946-0246
FX 464-1251

Aquatic Bioassessment

Since 2005, the Port of Stockton has conducted aquatic bioassessment monitoring of the waterways surrounding the port. Aquatic bioassessment is a technique for determining or monitoring the relative biological health and quality of an aquatic ecosystem based on the presence, absence, and relative numbers of particular macroinvertebrate species. Through the use of aquatic bioassessment techniques, the Port can detect potential sources of water pollution that would not be detected through conventional assessment techniques like water chemistry tests. The Port uses artificial substrate samplers to collect samples from the San Joaquin River and the surrounding tidal sloughs. The samplers imitate the naturally occurring substrate in the waterway and collect invertebrates through the natural processes of dispersal and colonization. The Port installs these samplers each spring and fall and collects them approximately four weeks later. Then the macroinvertebrate samples are taken to the lab, where a representative number of the critters are counted and identified. The resulting data are then used to calculate several indicators of ecosystem health.