8. Indicate the power plants that are part of the Volga-Kama Cascade of HPPs.

Analysis of the map:

The map displays a network of rivers and a legend for 'Conventional Symbols'. While the legend includes a symbol that appears to be related to energy infrastructure (a triangle with a line inside, possibly representing a dam or power station), there are no specific markings or labels on the map that identify which of these symbols correspond to the power plants of the Volga-Kama Cascade of HPPs.

Task 8: Indicate the power plants that are part of the Volga-Kama Cascade of HPPs.

To complete this task, the map would need to either:

1. Use a specific, distinct symbol for HPPs within the Volga-Kama cascade.
2. Label the identified symbols with the names of the respective power plants.
3. Provide a separate key or list that links the symbols on the map to the HPPs of the Volga-Kama cascade.

Since none of these conditions are met by the provided image, I cannot identify the specific power plants.

Conclusion: I am unable to complete task 8 based solely on the visual information present in the image.