Table 4.

Water quality classification in relation to chloride concentration according to various authors (after [80]).

level of workload/water quality class	notation by DVWKa [59]	Cl− mg l−1 DVWKa [59]	notation by NLÖb [81]	Cl− mg l−1 NLÖb [81]	notation by Ziemann [82]	Cl− mg l−1 Ziemann [82] a. silic waters b. carbon waters	notation by LAWA AK ZVc [83]	Cl− mg l−1 LAWA AK ZVc [83])	SO42− mg l−1 LAWA AK ZVc [83]
I	not or very slightly polluted by salts	0 to ≤50	not or very slightly polluted by salts	<200	unpolluted	a. ≤ 15 b. ≤ 25	geogenic background value	<25	<25
I–II	slightly polluted by salts	50 to ≤200	slightly polluted by salts	200 to <400	slightly polluted	a. ≥15 to ≤50 b. ≥25 to ≤100	very low pollution	<50	<50
II	moderately polluted by salts	200 to ≤400	moderately polluted by salts	400 to <1000	moderately polluted	a. ≥50 to ≤200 b. ≥100 to ≤200	moderate pollution	<100	<100
II–III	critically polluted by salts	400 to ≤800	critically polluted by salts	1000 to <2500	critically salt-polluted	≥200 to ≤600	distinct pollution	<200	<200
III	strongly polluted by salts	800 to ≤1500	strongly salanized	2500 to <5000	strongly salt-polluted	≥600 to 1500…2000	elevated pollution	<400	<400
III–IV	very strongly polluted by salts	1500 to ≤4500	very strongly salanized	5000 to <20 000	very strongly salanized	≥1500…2000 to ≤3000…50000	high pollution	<800	<800
IV	unduely polluted by salts	≥4500	unduely salanized	>20 000	very strongly salanized	≥3000 to 5000	very high pollution	>800	>800

^aDeutscher Verband für Wasserwirtschaft und Kulturbau (association of German water managers).

^bNiedersächsisches Landesamt für Ökologie (environmental institute of the German federal country Lower Saxony).

^cLänder-Arbeitsgemeinschaft Wasser Arbeitskreis Zielvorgaben (working group of the German federal countries who develop hydrochemical targets for waters).