Preheat oven to 350F.
Fold four large pieces of parchment paper in half to crease them. Open, and lay them flat.
On one side of crease, mound ¼ of the snow peas. Place salmon on top. Repeat with three additional pieces of parchment and remaining salmon and snow peas.
In a small bowl, whisk together miso, water, soy sauce and ginger.
Evenly divide miso mixture over salmon.
Fold parchment over salmon and scrunch the sides together to create a packet.
Place on a rimmed baking sheet. Bake until salmon is opaque throughout about 20 minutes.