OBJECTIVES: To quantify the levels of and variations in water quality parameters in Pohnpei Lagoon adjacent to Nett Point. To identify any vertical or horizontal stratification of water quality parameters adjacent to Nett Point. To determine how water quality near Nett Point is affected by tidal cycles, storm events, dredging, and seasonal changes.

APPROACH: The approach is to sample water quality throughout the water column at five locations near Nett Point at different stages of tide, tide exchange and river discharge and develop a predictive model. Three replicate samples of water quality parameters at all combinations of high, moderate and low levels of both river discharge and tide exchange are planned for flood and ebb tides. Total particulates, particulate organic matter (POM), salinity, temperature, dissolved oxygen and pH will be sampled. A location near the Pohnpei Passage, a location at the Tawenjokola River (T.R.) mouth and three locations adjacent to Nett Point pier will be sampled. The locations adjacent to Nett Point will be 15 meters north and south, and along the pier's east end. Salinity, temperature, pH and dissolved oxygen meter readings will be taken every meter from surface to bottom starting 0.5 meters below the surface. Water samples will be taken of identified water masses and analyzed for particulates. Small, moderate and large exchange and small, moderate and large precipitation periods will be targeted. Flood and ebb exchanges will be sampled separately. Both slack and one mid-exchange period will be sampled. Historic weather and tide data will be used to predict small, moderate and large tide exchange and precipitation periods. Three replicates of each tide and precipitation combination will be sampled; mean water quality under each combination of environmental conditions will be determined. Models that predict water quality based on the seasonal and tidal observations will be developed. The residence time of rainwater in the T.R. Estuary needs to be determined to best schedule storm event sampling; four stations will be sampled at high tide on successive days until three storms have passed. Sample stations will be at the estuary mouth, off Jountin, upstream of Kolonia, and off Nanukum. Vertical profiles of salinity and temperature will be taken proceeding up-estuary. Three storm events will be sampled for water quality; sampling will be conducted on four days; one sample day before, one during and two after the storm. The five locations will be sampled during low-slack, mid-flood, high- slack, and mid-ebb tides to form one sample day. Residence time of rainwater in the T.R. Estuary will determine the interval between storm-sampling days. Models that predict water quality based on the storm event and seasonal and tidal observations will be developed as a project end product. Dredge sampling is planned but may not be conducted; dredging operations at Nett Point have not been active since July 2000. Three dredging events will be sampled. Dredging event sampling will include one before, one during and one after dredging sample series. For dredge events, the Pohnpei Passage location will not be sampled and a location adjacent to the dredge will be added. The five locations will be sampled at high-slack, mid-ebb, low-slack, and mid-flood tides to form one sample series. Scheduling of dredge event sampling will be coordinated with the dredging company and attempt to be on days with high-slack tide near nine AM when dredging usually commences.

NON- TECHNICAL SUMMARY: Water quality data is not availble for Pohnpei Lagoon, baseline water quality values need to be determined for aquacultural development and environmental monitoring. To determine basline water quality conditions for Pohnpei Lagoon so that environmental degredation can be documented. To develope predictive water quality models to help in planning aquaculture projects near Nett Point.

PROGRESS: 2001/01 TO 2001/12 A total of 2846 measurements of estuarine temperature and conductivity have been taken to help determine storm water residence time in the estuary .Approximately 2000 of the measurements are entered into the computer awaiting analysis. Statistical software has been purchased and installed. Conductivity, not salinity, was measured because the salinity meter is broken and limited funds were better spent on other equipment. Field sampling has been postponed because of safety issues with the old outboard engines and problems obtaining sampling boat.

IMPACT: 2001/01 TO 2001/12 The residence time research will help this project and all future water quality-sampling projects design sampling programs, calculate flux (i.e. sediment and bacterial flux), and determine residence and flushing time. The research provides public exposure of active research program because of sampling at major bridge on Pohnpei. Discussion of water quality issues often occurs with local residence during sampling. Training of Micronesian assistants in temperature-conductivity sampling is completed.

PUBLICATIONS: 2001/01 TO 2001/12 None to Date. 2002.