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freshwater monitoring

Freshwater Monitoring

River and Stream Water Quality Monitoring

Data Quality Assurance

Quality Assurance Monitoring Plan and Standard Operating Procedures

Because freshwater data are used to assess waterbodies for trends, as well as possible 303(d) listing and subsequent water-cleanup investigations, the Freshwater Quality Monitoring team works hard to produce quality data, following strict protocols for sampling and processing. The Quality Assurance Monitoring Plan (QAMP) and Standard Operating Procedures (SOPs) are linked below.

The Quality Assurance Monitoring Plan: Continuous Monitoring for Oxygen, Temperature, pH, and Conductivity in Statewide Rivers and Streams is the 2009 plan that addresses quality-control issues in detail. Results are evaluated in annual reports. Field and laboratory staff members follow strict protocols for collecting and processing samples, maintaining and calibrating meters and equipment, and managing the data.

Addendum to Quality Assurance Monitoring Plan: Stream Ambient Water Quality Monitoring: Correction of Objectives, Responsibilities, and Addition of Analytes is a 2012 update and addendum to the QAMP.

Ambient Freshwater Biological and Water Quality Monitoring Standard Operating Procedures links to the SOPs used by the Freshwater Quality Monitoring group.

Frequent Calibration

The team spends a lot of time calibrating meters. Conductivity meters are calibrated twice daily and pH meters three times. They also check the calibration whenever a pH reading exceeds state standards. Modified Winkler titrations measure dissolved oxygen, because they are more accurate than meters, and because samplers often change elevation between sample stations.

Duplicate Samples

Duplicate samples are collected during each sampling trip, and duplicates are split in both the field and the lab. Some data-quality evaluations occur during data entry, and anomalies are confirmed with the lab. Preliminary data have undergone this level of review. To evaluate data quality, we collect a second set of samples at one randomly-chosen station during each sampling trip. This tests total variability, including short-term, instream variability. The second sample set is split in the field (to assess variability due to lab and field processing, plus analytical variability), and one of the splits is split again at the lab (to assess variability due to only lab processing plus analytical variability).

Overall data quality is evaluated annually against requirements specified in our Quality Assurance Monitoring Plan. Data are not considered finalized until after this evaluation.