Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
What is the River Mile with a RDB lock side and a pool length of 55.4?

### Inputs:
table_name: table, columns: ['Locks & Dam', 'Location [L ]', 'River Mile', 'Lock Side', 'Lock Lift/Drop (in feet)', 'Pool Length (miles)']

### Response:
SELECT River Mile FROM table WHERE Lock Side = rdb AND Pool Length (miles) = 55.4