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Water Quality Data Tiers

Water Quality Data Tiers identifies categories of data quality and their associated end uses. Data are
tiered based on the quality assurance and quality control program and documentation. While a Quality
Assurance Program Plan (QAPP) is not required for data submittal, the uses of the data will be limited
depending on the program. Data are tiered into three levels depending on the rigor of the QAPP and
the intended usage of the data.

Intended Data Use
TIERS Intended Data Use
TIER 1 Education, Environmental Health Screening
TIER 2 Basin Planning, Research, Effectiveness Monitoring, Targeting of Management Actions
TIER 3 Regulatory Assessments of Water Quality Standards Attainment

Tier Descriptions and Framework for Determining Tiers
There are diverse motivations for monitoring and diverse projects where data are collected. Broad data
quality requirements for each category are provided below.

Tier 1 Data and Information
Collected and used primarily for educational purposes. Tier 1 data cannot be used for regulatory
purposes. These data and information can be submitted to DWR staff directly or preferably through
using one of the community science applications in the NC Stream Watch Program. A QAPP is not
required, but is recommended. Tier 1 data and information are valuable in the Watershed Action Plan
(WAP) process for community involvement and project development.

These data can be used to:
 Provide location information on where monitoring is taking place;
 Provide on-the ground information for future site development;
 Indicate potential pollution hot spots;
 Prioritize sites for follow-up monitoring;
 Target restoration projects; and
 Highlight local, community projects.

Tier 2 Data and Information
Collected and used primarily for research and effectiveness monitoring. Tier 2 data cannot be used for
regulatory purposes. These data can be submitted to DWR staff directly. A QAPP will be required, but
not necessarily approved by DWR staff. Tier 2 data and information are valuable in the Watershed
Action Plan (WAP) process especially for effectiveness monitoring and for source determination and
abatement projects. A common application of Tier 2 data is through incorporation into the Basin
Planning Program. Some Tier 2 assessment information can be used in Integrated Reporting if
associated with watershed improvement projects.

These data can be used to:
 Include in Basin Plans for water quality reporting;
 Track the performance of Total Maximum Daily Load (TMDL) or WAP implementation
projects; and
 Be used for all uses identified in Tier 1.

Tier 3 Data and Information
Collected and used primarily for regulatory purposes. Tier 3 data are legally defensible data. Data used
for regulatory purposes must meet the same quality assurance and control as data collected by DWR
staff. The most common regulatory use is water quality assessment for Sections 305b(b) and 303(d) of
the Clean Water Act. These data should be submitted directly to DWR staff. A DWR-approved QAPP is
required. Data must also be processed by a state certified laboratory. Tier 3 data will be used for water
quality assessment alongside state collected data. Organizations submitting Tier 3 data will need to
contact DWR staff ahead of submittal (and collection if possible). Data will be submitted using the
format and processing provided by DWR staff. DWR staff will work with data submitters to document
the submittal process.

These data can be used to:
 Include in the biannual statewide assessment under Sections 305(b) and 303(d) of the Clean
Water Act; and
 All uses identified in Tier 1 and Tier 2.