Except as provided in subsection (b) of this section and section
1319
(g)(6) of this title, any citizen may commence a civil action on his own behalf—
The district courts shall have jurisdiction, without regard to the amount in controversy or the citizenship of the parties, to enforce such an effluent standard or limitation, or such an order, or to order the Administrator to perform such act or duty, as the case may be, and to apply any appropriate civil penalties under section
1319
(d) of this title.