Heat oven to 350 �F.
Peel shrimp from shell. If using frozen shrimp, do not thaw and peel in cold water.
Remove the vein from each shrimp by making a shallow lengthwise cut down the back.
In a 13x9 baking dish, mix together the water, mushrooms, rice, onion, shrimp, salt, and ginger.
Tightly cover the baking dish with aluminum foil.
Bake in oven until liquid is gone and shrimp are pink, about 40 minutes.
Remove the dish from oven and pull back aluminum foil. Stir in water chestnuts, mandarin oranges, and snow peas.
Replace aluminum foil and allow to stand; do not place back in the oven.
The dish is ready when the snow peas are hot.