More sites should be selected if the treatment area covers a large area. Sample sites should be located accurately. Only if the same location is consistently sampled can temporal changes in water quality be interpreted with confidence. Use accurately written station location descriptions, mark the sites in the field with flagging, and locate them on maps. If sampling in a fish stream, take the water temperature at the sampling location.
Temperature is necessary to assess ammonia levels.
The samples must be received by the laboratory within 72 hours of collection. C. Sample frequency Pre-application monitoring should be conducted for two weeks. Obtain three samples, twice per week at both control and treatment area sites. Obtain results back from the laboratory in a timely manner to enable changes to be made in the planned treatments if the analysis shows high levels of natural nitrogen or phosphorus. Post-application monitoring should be conducted immediately following fertilizer application and then twice per week for three weeks.