Very finely dice the garlic and both the white and the green parts of the leek, then sauté over medium heat in the bottom of a soup pot with a pinch of salt until the leeks begin to soften, about 10 minutes. Sprinkle with Old Bay Seafood Seasoning.
Stir in the water, the light whipping cream, the sour cream, the white wine, the saffron, the thyme, and the basil. Bring to a low boil, then add the mixed shellfish. Reduce heat to a steady simmer and cook, uncovered, for 10 minutes.
Add the salmon and cook for an additional 10 minutes.