Developing Grading Guidelines
To ensure clarity and consistency, CoRHAF employs an academic grading system for conveying stream health assessment outcomes, regardless of whether supporting information was generated qualitatively through rapid surveys or quantitatively through advanced analyses. Grading Guidelines define the criteria required for assignment of functional condition rankings to Drivers, Components, or Metrics. The application of Grading Guidelines to both quantitative and qualitative assessments provides a means for translating assessment results with differing scales and units into concise summaries of condition, presented in a format that is readily understood by diverse audiences. The development of Grading Guidelines can occur at any level of the CoRHAF structure hierarchy. Irrespective of the level where they are developed, Grading Guidelines should reflect the basic expectations for functional condition detailed in the table below:
| CoRHAF Grade | Functional Condition | Degree of Alteration | Degree of Impairment | General Description |
|---|---|---|---|---|
| A | Reference Standard | Negligible | Self-Sustaining | Characteristic or process is self-sustaining and supports function appropriate to sustain river health. No management is required to sustain and protect function. |
| B | Highly Functioning | Mild | Mild | Characteristic or process maintains essential qualities that support a high level of ecological function. The influence of stressors is detectable at a minor level. Limited management is required to sustain function. |
| C | Functioning | Significant | Substantial | Characteristic or process is diminished by stressors that substantially impair functioning but basic, natural, functioning persists. Management is required to maintain function. |
| D | Functionally Impaired | Severe | Severe | Characteristic or process is severely degraded by stressors. Intensive, active management is required to maintain residual functioning and river health. |
| F | Non-functional | Profound | Profound | Characteristic or process is profoundly impaired by stressors rendering it incapable of supporting basic river functions. |
Grading Guidelines reflect a degree of departure from the conceptual Reference Standard–the functional condition of a stream or river in its unaltered natural state. Guidelines should be defined in such a way that only Drivers, Components, or Metrics that resemble the Reference Standard receive an “A” ranking. Grading Guidelines for “B” through “F” rankings should describe increasing degrees of departure from the Reference Standard.
Mitigation requirement thresholds, minimum instream flow water rights, and other management criteria/objectives that reflect altered river conditions should never be used to establish Grading Guidelines for Highly-Functioning (“B”) or Reference Standard (“A”) functional conditions. Instead, such criteria/objectives may be used to delineate Functioning (“C”) or Functionally-Impaired (“D”) conditions.
The technical team will create or modify Grading Guidelines as required by the customized assessment framework selected for the study. The CoRHAF Workbook contains a full set of Grading Guidelines for default list of CoRHAF Drivers and Components. These Grading Guidelines may be adopted, modified or replaced to meet the needs of a specific assessment. Adopted Grading Guidelines can serve as a field guide that helps technicians calibrate observations during rapid assessments, as an objective rationale for classification of quantitative data, and as a translation tool for stakeholders who want to better understand assessment outcomes.
Creating Custom Grading Guidelines
The process of creating custom Grading Guidelines is responsive to the process used to customize the CoRHAF organizational structure with Drivers, Components, and Metrics. The development of Grading Guidelines must occur prior to the assessment of river conditions. Grading Guidelines should be developed for the lowest level of any branch in the Driver → Component → Metric hierarchy. For example, if conditions for a given Driver are assessed down to the Metric level, quantitative guidelines should be defined at the Metric level but not at the levels above. If instead, conditions are assessed at the Driver or Component level, qualitative grading guidelines should be defined at the Driver or Component level, respectively.
In most cases, CoRHAF users should avoid defining Grading Guidelines at multiple levels along a single branch in the Driver → Component → Metric hierarchy. Doing so is likely either to result in duplicative grading guidelines between levels or produce a guideline at one level that conflicts with a guideline defined at a higher or lower level. If groups are determined to develop Grading Guidelines at multiple levels along a single branch in the framework hierarchy, care must be taken to ensure that the guidelines along a single branch do not conflict. Higher level guidelines should explicitly reference the ranking criteria used by lower level guidelines.
Considerations for Spatial Scope and Scale
Grading guidelines should reflect the expectations among stakeholders and Technical Teams regarding the variability in conditions across the assessment area. In some cases, it may be acceptable to develop Grading Guidelines that apply equally across long stream segments or entire watersheds. Flow Regime and Water Quality Components or Metrics may fall into this category. For other Components or Metrics, unique Grading Guidelines may be appropriate for specific reaches of stream or portions of the watershed. For example, expected riparian conditions can vary widely between narrow canyon reaches and low-gradient alluvial reaches. If an assessment area includes both morphologies, distinct Grading Guidelines may be developed for each case. Where Grading Guidelines are applied to Drivers and Components at different spatial units, special care must be applied during the communication of results.
Guideline Types
Selection of Grading Guidelines at the Metric level will be quantitative in the vast majority of cases. Grading Guidelines defined at the Component or Driver level will generally take a qualitative form. A smaller number of use cases may result in the development of hybrid Grading Guidelines. Each type of guideline has its place and is characterized by unique advantages and limitations.
Quantitative Guidelines
Quantitative Guidelines rely on numerical data and analysis results to classify conditions based on measurable thresholds or intervals. Quantitative guidelines enjoy a high degree of objectivity. Where quantitative guidelines are employed, numerical evidence provides a transparent rationale for assigned grades. Numerical evidence may come from environmental sampling, simulation modeling, geostatistical analysis of spatial data coverages, statistical analysis of time series data, etc. Development of quantitative guidelines may require engagement of technical experts with specific domain knowledge to ensure appropriate mapping between expected numerical results and the functional condition criteria reflected in the CoRHAF grading schema.
Qualitative Guidelines
Qualitative guidelines are descriptive narratives of functional condition. They do not rely on numerical evidence for evaluation but can include numerical ranges to help calibrate field evaluations. Qualitative guidelines rely on the expert opinion of the technician, engineer, or scientist carrying out assessment activities. Qualitative Grading Guidelines should cover the range of expected conditions for a Driver or Component in a way that that can help calibrate the the activities of the individual or team performing the assessment. The example set of qualitative guidelines included in the CoRHAF Workbook are generally applicable across many streams and rivers in Colorado. Individuals and teams can leverage previous professional experiences in similar settings, meta-analyses of previous reporting, rapid field assessments, and other means to assign grades for functional condition. The general subjectivity of qualitative Grading Guidelines makes it critical that any grade assigned in this manner is accompanied by a narrative rational for the assignment.
Hybrid Grading Guidelines
In some special cases, hybrid Grading Guidelines may be developed to reflect both on quantitative data analysis results and qualitative observations or expert-opinion. These Grading Guidelines are the most difficult to implement successfully due to the risk for imposing mutually exclusive qualitative and quantitative conditions within on or more grade levels. Despite this difficulty, they may be preferred by some stakeholder groups and Technical Teams. In particular, they may find utility in settings where the CoRHAF organizational structure is detailed down to the Metric level for one Component but the stakeholders or Technical Team members do not feel that a single Metric captures the breadth of Component behaviors or characteristics of interest. If these groups intend to supplement quantitative data at the Metric level with qualitative data at the Component level, they may benefit from development of hybrid Grading Guidelines.
Reflections on Method Selection
The process used to develop Grading Guidelines should not occur in isolation from the process used to identify and select assessment methods. In fact, Grading Guidelines generally respond directly to methods selected to evaluate river health conditions. Rapid assessment methods are critical to many assessment efforts because they can be quickly implemented and broadly applied. Rapid assessments generally require qualitative Grading Guidelines. Methods capable of producing quantitative results for a particular Metric can be accompanied by quantitative Grading Guidelines. There is no advantage in the development of quantitative Grading Guidelines that cannot be assessed due to a lack of resources or technical expertise. Conversely, development of qualitative Grading Guidelines may be poorly matched for a Component or Metric that Technical Teams intend to assess by way of quantitative simulation modeling or data analysis. Several attributes of qualitative and quantitative grading guidelines relevant to assessment activities are outlined in the table below:
| Consideration | Qualitative Guidelines | Quantitative Guidelines |
|---|---|---|
| Guideline development difficulty | Straightforward | Moderate to Difficult |
| Grading approach | Best professional judgement | Objective data analysis |
| Assessment method data requirements | Flexible | High |
| Assessment method cost | Low | High |
| Scope of assessment results | Broadly applicable | Site specific |
