Conclusions
141
Step 7: Monitor to Determine
Effectiveness of Load Reduction
The objective of the TMDL process is to keep selenium concentrations
below levels that are toxic to biota. Therefore, it is important to use
environmental quality goals as a guide in follow-up effectiveness monitoring. For this purpose, I recommend that the following guidelines be
used as maximum allowable selenium concentrations (see Chapter 2):
Water =2 lAg SelL, filtered samples (0.45 lAm pore size)
Sediment =2 Ilg Se/g dry weight
Benthic invertebrates =3 Ilg Se/g dry weight
Fish tissues:
whole body =4 Ilg Se/g dry weight
skeletal muscle (skinless fillets) =8 Ilg Se/g dry weight
liver =12 Ilg Se/g dry weight
ovary and eggs =10 Ilg Se/g dry weight
Aquatic bird tissues:
liver =10 Ilg Se/g dry weight
eggs =7 Ilg Se/g dry weight
These guideline values represent concentrations that are protective
of fish and wildlife reproduction. Monitor selenium residues annually
and apply the Protocol (same as for Step 2) to determine if hazard is
reduced to either the minimal or no hazard level. If it is, then no
further load reductions are necessary-conduct environmental monitoring every 3 years. If it is not, repeat Step 5 to determine the additional amount of selenium load reduction necessary, implement load
reduction, and monitor annually. The entire TMDL process is summarized in Figure 8.1.
Conclusions
On the surface, the TMDL program may seem to be a formidable USEPA
regulatory requirement that generates uncertainty, apprehension, and
is not easily addressed. Without adequate technical guidance, this may
be true in many cases. However, the straightforward, 7-step procedure
given in this chapter takes away the uncertainty and allows environmentally safe TMDL limits to be set for selenium. This method is tailored to account for selenium's ability to bioaccumulate and cause
reproductive toxicity to fish and wildlife. A key part of the method is
the identification and use of a Hydrological Unit (HU) as the basis for
evaluation. The HU approach provides the contaminant-specific site
141
Step 7: Monitor to Determine
Effectiveness of Load Reduction
The objective of the TMDL process is to keep selenium concentrations
below levels that are toxic to biota. Therefore, it is important to use
environmental quality goals as a guide in follow-up effectiveness monitoring. For this purpose, I recommend that the following guidelines be
used as maximum allowable selenium concentrations (see Chapter 2):
Water =2 lAg SelL, filtered samples (0.45 lAm pore size)
Sediment =2 Ilg Se/g dry weight
Benthic invertebrates =3 Ilg Se/g dry weight
Fish tissues:
whole body =4 Ilg Se/g dry weight
skeletal muscle (skinless fillets) =8 Ilg Se/g dry weight
liver =12 Ilg Se/g dry weight
ovary and eggs =10 Ilg Se/g dry weight
Aquatic bird tissues:
liver =10 Ilg Se/g dry weight
eggs =7 Ilg Se/g dry weight
These guideline values represent concentrations that are protective
of fish and wildlife reproduction. Monitor selenium residues annually
and apply the Protocol (same as for Step 2) to determine if hazard is
reduced to either the minimal or no hazard level. If it is, then no
further load reductions are necessary-conduct environmental monitoring every 3 years. If it is not, repeat Step 5 to determine the additional amount of selenium load reduction necessary, implement load
reduction, and monitor annually. The entire TMDL process is summarized in Figure 8.1.
Conclusions
On the surface, the TMDL program may seem to be a formidable USEPA
regulatory requirement that generates uncertainty, apprehension, and
is not easily addressed. Without adequate technical guidance, this may
be true in many cases. However, the straightforward, 7-step procedure
given in this chapter takes away the uncertainty and allows environmentally safe TMDL limits to be set for selenium. This method is tailored to account for selenium's ability to bioaccumulate and cause
reproductive toxicity to fish and wildlife. A key part of the method is
the identification and use of a Hydrological Unit (HU) as the basis for
evaluation. The HU approach provides the contaminant-specific site