Around £100m is being spent on heroin and crack cocaine in Derbyshire every year, according to research.
The Derbyshire Drug Market Project was carried out over a three-year period from April 2001 until June 2004.
It aimed to target drug markets across the county through the twin track of enforcement and treatment to reduce the use of Class A drugs.
Police, who worked together with drug treatment workers, arrested over 200 drug dealers.
The project was funded by the Treasury, Derby City Council, Derbyshire County Council, Derbyshire Constabulary and local Primary Care Trusts.
It involved partnerships between the police and drug treatment workers in Bolsover, Chesterfield, Ilkeston, Matlock and New Mills.
Adrian Evans, chief executive of the Derbyshire Drug Mapping Project, said: "The project made it possible for us to explore new ways of approaching enforcement and treatment within Derbyshire,
"There are about 10,000 identified problem heroin and/or crack users in Derby and Derbyshire, who spend between £8,000 and £13,000 on drugs each year."