4.2.21 Suspended Solids Discharge Standards for Permitted Activity Rules in Chapters 4.2 and 4.3
- In any river or stream (including Hydro Electricity Reservoirs): the suspended solids concentrations as a result of works associated with a structure in the stream downstream of the structure shall not exceed the suspended solids concentration as measured at the same time in the stream immediately upstream of the structure.
- In any lake (excluding Hydro Electricity Reservoirs): as a result of works associated with a structure the suspended solids concentration in the lake shall not exceed the ambient lake concentration (i.e. as measured in the lake in areas unaffected by the discharge).
- The restrictions in a) and b) shall not apply with regard to the erection, reconstruction, placement, alteration or removal of a structure within a water body within any 24 hour period within 30 days from commencement of the works, except in:
- Significant Indigenous Fisheries and Fish Habitat Class waters during August to December inclusive.
- Significant Trout Fisheries and Trout Habitat class waters during May to September inclusive.
The point at which compliance with standards a) and b) shall be measured is:
- For rivers and streams (including Hydro Electricity Reservoirs): at a distance downstream of the discharge point (or site of the activity) which is three times the width of the river or stream and which in any instance does not exceed 200 metres from the point of discharge.
- For lakes (other than Hyrdo Electricity Reservoirs): at a distance of 15 metres from the location of the discharge or the activity.
- As Hydro Electricity Reservoirs have significant flows it is more appropriate to use the river compliance point (maximum of 200m from point of discharge), rather than one intended for lakes with very low current or flow velocities.