Tier 1 and 2 Tidal Monitoring

All Tier 1 and Tier 2 tidal water quality monitoring projects submitting data to the CMC follow the EPA approved CMC Water Quality Monitoring in Tidal Waters Quality Assurance Project Plan (approved in 2022). Any group that does not follow appropriate methods or quality assurance procedures defined in the Tidal QAPP will be labeled as provisional, provisional Tier 1 or provisional Tier 2 until they meet the minimum requirements for their designated tier.

Sample Collection

Tier 1 and Tier 2 tidal water quality monitoring groups collect discrete surface samples or depth profiles using in-situ sensors or probes, monitoring kits, or lab grab samples that utilize reliable QA procedures and standardized protocols in tidal waters of the Chesapeake Bay watershed. Most programs use a combination of techniques to analyze a suite of parameters based on resources available. All equipment, technologies and sampling methods selected for this project are used to monitor baseline surface water conditions following the EPA volunteer monitoring methods for streams and estuaries. Individual groups may have more specific methods to meet specific objectives, like targeting restorations projects, tracking bacteria levels for human health, etc.

Samples should be collected from mid-channel when possible and can be collected from a boat, a bridge, or a pier/dock. Samples can be collected from the shoreline if needed, but a sampling pole or bucket should be used to collect the sample away from the shore. Surface samples are collected at either 0.3m, 0.5m or 1.0m below the surface of the water depending on the capabilities of the equipment and the depth of the waterway.

Depth profiles should take measurements from the bottom to the top of the water column. For depths >3m, samples are taken 1.0m above the bottom, then 1.0m increments up to 1.0m below the surface, Maryland monitoring groups take an additional measurement at 0.5m below the surface (ie. at a 6.4m site, measurements are taken at 5.4m, 5.0m, 4.0m, 3.0m, 2.0m, 1.0m, and 0.5m (in Maryland)). If a site is ≤3m, measurements are taken at 1.0m off the bottom and 1.0m below the surface in Virginia and 0.5m below the surface in Maryland.


The tidal water quality monitoring projects sample the following parameters. Each monitoring group selects parameters, equipment and analytical methods used for their program based on their individual monitoring needs and desired data use goals. All monitoring groups collect depth profile samples should collect at a minimum temperature, dissolved oxygen and salinity data.

  • Ammonia-nitrogen (lab)
  • Bacteria (e.coli/enterococcus) (field or lab)
  • Chlorophyll a (lab)
  • Conductivity (field)
  • Dissolved Oxygen (field)
  • Nitrate-nitrogen (field or lab)
  • Nitrite-nitrogen (field or lab)
  • Orthophosphate (field or lab)
  • pH (field)
  • Salinity (field)
  • Total Dissolved Solids (field)
  • Total Suspended Solids (lab)
  • Total Nitrogen (lab)
  • Total Phosphorus (lab)
  • Water Clarity (field)
  • Water Temperature (field)

The full list of approved parameters, sampling procedures, and equipment along with the highest achievable tier and the requirements to meet that tier designation for field data are listed in the CMC Tidal QAPP.

Monitoring Timelines

Each monitoring group participating has their own project timeline tailored to their specific monitoring program and data needs. Typical sampling frequencies include, but are not limited to:

  • Once monthly water quality sampling – typically occurs year-round when possible, but can be done at a minimum from March to November.
  • Biweekly water quality sampling – typically occurs year-round when possible, but can be done at a minimum from March to November.
  • Weekly water quality sampling – typically occurs during the summer months, May through September/October.
  • Combination of timeframes – some monitoring programs perform weekly sample collection in the summer and monthly sample collection the rest of the year.

Data Use

The primary intended data user for Tier 1 and 2 data is the monitoring group collecting the data. Each monitoring group submitting data to the CMC has their own defined data use goals based on the local interests and water quality concerns.

Additionally, data are uploaded to the Chesapeake Bay Program annually and are available to fill in data gaps throughout CBP workgroups.

Lastly, monitoring groups can opt in to data sharing with state agencies in response to Data Solicitation Notices for the State’s Integrated Reports. Each state has their own standards, criteria, and processes for utilizing volunteer data in their Integrated Reports.

Service Providers

The Alliance works with tidal monitoring groups in Virginia and Maryland. UMCES works with tidal monitoring groups in Maryland and any monitoring groups to provide data interpretation and visualization workshops.

If you are interested in starting a new tidal monitoring program or want your existing tidal monitoring program to be integrated into the CMC, fill out this Application for Assistance to connect with your local Service Provider.