Publication Summary

A receiving water study was performed in the Joe Creek estuary in order to address water quality concerns related to the proposed expansion of the Pacific Beach Wastewater Treatment Plant. Lower Joe Creek is a strongly stratified lagoon-like estuarine system with a freshwater lens overlying a saline water mass whose circulation is restricted by a shallow sill at the mouth of the estuary. Parameters that were monitored include: flow, velocity, dissolved oxygen, temperature, conductivity, salinity, 5-day biological oxygen demand (BOD5), ammonia, total suspended solids, and fecal coliform bacteria.

A receiving water study was performed in the Joe Creek estuary in order to address water quality concerns related to the proposed expansion of the Pacific Beach Wastewater Treatment Plant. Lower Joe Creek is a strongly stratified lagoon-like estuarine system with a freshwater lens overlying a saline water mass whose circulation is restricted by a shallow sill at the mouth of the estuary. Parameters that were monitored include: flow, velocity, dissolved oxygen, temperature, conductivity, salinity, 5-day biological oxygen demand (BOD5), ammonia, total suspended solids, and fecal coliform bacteria.

Sampling occurred during critical conditions of low streamflow and restricted tidal exchange. Water quality at many sites in the lower Joe Creek system does not meet freshwater or marine water Class AA standards for dissolved oxygen or bacteria. Survey results support previously recommended effluent limits for the proposed upgrade which should be protective of water quality in the estuary, even though BOD5 loading to Joe Creek from the proposed upgrade will be from 6 to 8 times greater than the current facility's BOD5 loading to Joe Creek.