The Environment Agency / DEFRA - Surface Water Pollution Risk for Your Environment Permit has two interesting sheets embedded within it -

Estuaries and coastal water specific pollutant and operation environmental quality standards - Estuaries and coastal water - pollutants and EQS

and

Estuaries and coastal water priority hazardous substances priority substances and other pollutants environmental quality standards - Estuaries and coastal water - hazardous substances and EQS

CEFAS - Action Levels