Drain clams, reserving liquid. Finely mince clams; set aside.
Sauté salt pork in a large Dutch oven until golden brown; remove salt pork and discard, reserving pan drippings in Dutch oven. Sauté onion in pan drippings until tender. Add potatoes, bay leaves, salt, and pepper; stir well. Add enough water to clam liquid to equal 3 cups; add to Dutch oven, stirring well. Bring to a boil. Reduce heat; cover and simmer 15 minutes.
Melt butter in a heavy saucepan over low heat; add flour, stirring until smooth. Cook 1 minute, stirring constantly. Gradually add scalded milk and half-and-half; cook over medium heat, stirring constantly, until slightly thickened.
Stir cream sauce and reserved minced clams into vegetable mixture; simmer 20 minutes. Serve warm in individual soup bowls.