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Aquatic Life Use Support (ALUS)

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Table 4. Hierarchy of Physical/chemical Data Levels for Evaluation of Aquatic Life Use Attainment

Level of Infoa Technical Components Spatial/Temporal Coverage Data Quality c
1 Any one of the following:
  • Water quality monitoring using grab water sampling
  • Water data extrapolated from an upstream or downstream station where homogeneous conditions are expected
  • Monitoring data >5 years old without further validation
  • Best professional judgment based on land use data, source locations
 Low spatial and temporal coverage:
  • Quarterly or less frequent sampling with limited period of record (e.g., 1 day)
  • Limited data during key periods or at high or low flows (critical hydrological regimes)b.
 Unknown/Low
2 Any one of the following:
  • Water quality monitoring using grab water sampling
  • Rotating basin surveys involving multiple visits or automatic sampling
  • Synthesis of existing or historical information on fish contamination levels
  • Screening models based on loadings data (not calibrated or verified).
 Moderate spatial and temporal coverage:
  • Bimonthly or quarterly sampling during key periods (e.g., spring/summer months
  • Fish spawning seasons, including limited water quality data at high and low flows
  • Short period of record over a period of days or multiple visits during a year or season.
 Low/Moderate
3 Any one of the following:
  • Composite or a series of grab water sampling used (diurnal coverage as appropriate)
  • Calibrated models (calibration data <5 years old).
 Broad spatial and temporal (long-term, e.g., >3 years) coverage of site with sufficient frequency and coverage to capture acute events:
  • Typically, monthly sampling during key periods (e.g., spring/ summer months, fish spawning seasons), multiple samples at high and low flows
  • Lengthy period of record (sampling over a period of months).
 Moderate/High
4 All of the following:
  • Water quality monitoring using composite or series or grab samples (diurnal coverage as appropriate)
  • Limited sediment quality sampling and fish tissue analyses at sites with high probability of contamination.
 Broad spatial (several sites) and temporal (long-term, e.g., >3 years) coverage of site with sufficient frequency and parametric coverage to capture acute events, chronic conditions, and all other potential P/C impacts
  • Monthly sampling during key periods (e.g., spring/summer months
  • Fish spawning seasons) including multiple samples at high and low flows
  • Continuous monitoring.
 High

NOTE: Physical refers to physical water parameters (e.g., temperature, pH, dissolved oxygen, turbidity, color, conductivity)

a Level of information refers to rigor of physical/chemical sampling and analysis, where 1 = lowest and 4 = highest.

b Even a short period of record can indicate a high confidence of impairment based on P/C data; 3 years of data are not required to demonstrate impairment. For example, a single visit to a stream with severe acid mine drainage impacts (high metals, low pH) can result in high confidence of nonsupport. However, long-term monitoring may be needed to establish full support.

c Refers to ability of the physical/chemical endpoints to detect impairment or to differentiate along a gradient of environmental conditions.

Biological Indicators

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