Freshwater slightly to moderately disturbed condition (SMD)

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Slightly to moderately disturbed (SMD) condition is defined by ANZECC 2000 as ecosystems in which “aquatic biological diversity may have been adversely affected to a relatively small but measurable degree by human activity. The biological communities remain in a healthy condition and ecosystem integrity is largely retained. Typically, freshwater systems would have slightly to moderately cleared catchments and/or reasonably intact riparian vegetation. Slightly to moderately disturbed systems could include rural streams receiving runoff from land disturbed to varying degrees by grazing or pastoralism..“ (ANZECC 2000; Chapter 3).

SD slightly disturbed freshwater ecosystems

Slightly disturbed freshwater wetland locations (e.g. mapped as ‘Riverine’, ‘Lacustrine’ or ‘Palustrine’ Wetland in the Qld EPA Wetland mapping) that have been identified by a technical panel or other information sources as having a small degree of change.

Significant conservation values/remnant natural assets will be identified in these waterways (so that these can be recognised for protection/improvement).

Management intent for SD freshwater ecosystems

Protect natural condition/values and improve any slightly modified components towards natural condition

(ANZECC, 2000: p 3.3-7: “stakeholders may also decide to… improve or restore the ecosystem to a substantially unmodified condition, depending on the situation”)

WQ guidelines to protect SD freshwater ecosystems

  • Toxicants in water: No change to natural: interpreted as 99% species protected with 50% certainty (ANZECC, 2000; Table 3.4.1, 3.4.2)

-ANZECC, 2000; Table 3.4.2 note C: “Jurisdictions may choose 99% values for some ecosystems that are more towards the slightly disturbed end of the continuum”

-ANZECC, 2000; Chapter 8. Supporting Rationale and Background Information, “For some slightly-moderately disturbed ecosystems which have higher quality waters, managers may prefer to use the 99% protection level.”

  • Toxicants in sediments: No change to natural: interpreted as no detectable chemicals from human activities, and naturally occurring toxicants not to exceed background concentrations (ANZECC, 2000; p3.5-1)
  • Physico-chemical: No change to natural: interpreted by QWQG (2006; Appendix D) as maintaining the natural distribution of water quality using 20th, 50th and 80th percentiles of good quality “natural” reference sites as a basis for maintaining natural variability
  • Biological: No change to natural biodiversity: interpreted by maintenance of biological indicators relative to suitable reference condition (ANZECC, 2000; Table 3.1.2).

MD moderately disturbed freshwater ecosystems

Moderately disturbed ecosystems Freshwater wetland locations (e.g. mapped as ‘Riverine’, ‘Lacustrine’ or ‘Palustrine’ Wetland in the Qld EPA Wetland mapping) identified by technical panel or other information sources as having a moderate degree of change (eg not identified as HEV, SD, or HD).

Significant conservation values/remnant natural assets will also be indentified in MD waterways (so that these can be recognised for protection/improvement).

Management intent for MD freshwater ecosystems

Maintain/improve water quality - protect any remnant values/assets (with some allowance for development).

(ANZECC 2000; 3.1-11: “An increased level of change might be acceptable…maintenance of biological diversity relative to a suitable reference condition should be a key management goal”).

WQ guidelines to protect MD freshwater ecosystems

  • Toxicants in water: 95% (and in some cases 99%) spp protected with 50% certainty (Refer ANZECC, 2000, Table 3.4.1, 3.4.2)
  • Toxicants in sediments:Refer to ANZECC, 2000 Table 3.5.1.

> 90% of individuals protected (QWQG, 2006; Table 3.4.3)

  • Physico-chemical: Guideline based on 20th and /or 80th percentiles of reference data from good quality reference sites (QWQG, 2006; Tables 3.4.3, 3.4.4)
  • Biological: Guideline based on 20th and /or 80th percentiles of reference data from good quality reference sites (QWQG, 2006; Tables 3.4.3, 3.4.4)

Reference documents

Australian and New Zealand Guidelines for Fresh and Marine Water Quality (ANZECC 2000)

Queensland Water Quality Guidelines