{
  "url": "https://openlegislation.uk/surface-waters-classification-scotland-regulations-1990/schedule",
  "json_url": "https://openlegislation.uk/surface-waters-classification-scotland-regulations-1990/schedule.json",
  "legislation": "uksi/1990/121",
  "legislation_title": "The Surface Waters (Classification) (Scotland) Regulations 1990",
  "legislation_url": "https://openlegislation.uk/surface-waters-classification-scotland-regulations-1990",
  "path": "schedule",
  "kind": "schedule",
  "number": null,
  "heading": "Criteria for the classification of waters",
  "text": "The limits set out below are maxima\n(1)\n(2)\n(3)\n(4)\n(5)\nNo. in Annex II to 75/440/EEC\nParameters\nDW1\nDW2\nDW3\nNote\n(1) The value is an upper limit set in relation to the mean annual temperature (high and low).\n2\nColoration (after simple filtration)\nmg/1 Pt Scale\n20\n100\n200\n4\nTemperature\n°C\n25\n25\n25\n7\nNitrates\nmg/1 NO3\n50\n50\n50\n8(1)\nFluorides\nmg/1 F\n1.5\n10\nDissolved iron\nmg/1 Fe\n0.3\n2\n12\nCopper\nmg/1 Cu\n0.05\n13\nZinc\nmg/1 Zn\n3\n5\n5\n19\nArsenic\nmg/1 As\n0.05\n0.05\n0.1\n20\nCadmium\nmg/1 Cd\n0.005\n0.005\n0.005\n21\nTotal chromium\nmg/1 Cr\n0.05\n0.05\n0.05\n22\nLead\nmg/1 Pb\n0.05\n0.05\n0.05\n23\nSelenium\nmg/1 Se\n0.01\n0.01\n0.01\n24\nMercury\nmg/1 Hg\n0.001\n0.001\n0.001\n25\nBarium\nmg/1 Ba\n0.1\n1\n1\n26\nCyanide\nmg/1 Cn\n0.05\n0.05\n0.05\n27\nSulphates\nmg/1 SO4\n250\n250\n250\n31\nPhenols (phenol index) paranitraniline 4 aminoantipyrine\nmg/1 C6H5OH\n0.001\n0.005\n0.1\n32\nDissolved or emulsified hydrocarbons (after extraction by petroleum ether)\nmg/1\n0.05\n0.2\n1\n33\nPolycyclic aromatic hydrocarbons\nmg/1\n0.0002\n0.0002\n0.001\n34\nTotal pesticides (parathion, BHC, dieldrin)\nmg/1\n0.001\n0.0025\n0.005\n39\nAmmonia\nmg/1 NH4\n1.5\n4",
  "extent": null,
  "status": null,
  "version": "current",
  "annotations": [],
  "outstanding_effects": [],
  "provenance": {
    "source": "legislation.gov.uk",
    "source_url": "https://www.legislation.gov.uk/uksi/1990/121/schedule",
    "retrieved_at": "2026-10-29T15:29:07.645038+00:00"
  },
  "licence": "Open Government Licence v3.0",
  "licence_url": "https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/",
  "attribution": "Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives."
}