Strain clams and reserve the juice in a measuring cup.  Add more clam juice to equal 2 cups total.  Set aside.

Melt butter in a large saucepan.  Cook onions on low heat until translucent. Add celery and cook a few more minutes.    Add flour and stir until the flour is coated in the butter.  Cook for a few more minutes on low heat.

Add premeasured clam juice, thyme sprigs and bay leaf to butter mixture and stir until combined.  Add in potatoes and cook until potatoes are tender, stirring occasionally as mixture thickens.  As it thickens begin to add milk.  Once potatoes are tender, remove from heat.