Officers are dealing with oil pollution close to the River Erewash in Carburton.
Booms, temporary floating barriers are being used to contain the spill.
Dyes are also being used to try and trace the source of the pollution.
Paul Reeves who works for the Enviroment agency tweeeted: "The clean-up on the River #Poulter at #Carburton continues. We've deployed more booms to contain the #diesel & protect @NTClumberPark lake."