The massive party at Cadover Bridge, near Shaugh Prior, took place between Boxing Day and Friday, December 27.
Two people were arrested and hundreds of cars were found parked near stages set up in a quarry, police said.
Officers also found stolen nitrous oxide canisters and a huge amount of waste, including human excrement, in the surrounding area.
Closed roads have since reopened.
Sgt Rob Wilson, of Ivybridge & Rural Police, described the event as a “large-scale” illegal party and "not a place for a peaceful post-Christmas dog walk".
Ch Supt Matt Longman said the force had been concerned "both for the people in attendance and the impact on the local community."
An 18-year-old man, from Wilshire, was arrested on suspicion of possessing Class A and C drugs.
A 27-year-old man, from Kingskerswell, Devon, was arrested on suspicion of driving under the influence.
There was also a minor single-vehicle crash in the area, but no one was injured.
South West Ambulance said it treated a patient at the rave in the early hours of Friday morning for minor injuries.
Ch Supt Matt Longman, of Devon and Cornwall Police, said: “We attended the scene and worked with individuals to bring about closing the event down.
"Roads were gridlocked and there was limited access for emergency vehicles to attend should they be needed.
“There was at least one medical incident that we could not get an ambulance to, this person was eventually taken to hospital.
“This highlights the importance of maintaining public safety.
“We have now re-opened roads as members of the public leave the location and the area is cleared.”
Sgt Tim Perrin, of Totnes Police, said: “Officers discovered a collection of stolen Nitrous Oxide canisters at a rave site at Cadover Bridge.
“We would advise dog walkers to avoid the area due to the amount of waste, including human excrement, at the location for the next few days.”
Sgt Wilson said: “Events like this carry risk and not an insignificant amount of it.
“As a result of the incident, officers were deployed from across Devon and Cornwall and specialist units and partner agencies were called on to assist.
“It is not yet possible for us to quantify what our actions have prevented happening.
“However, first-hand experience has taught me that serious road traffic collisions may have been prevented by the arrests made on suspicion of drink or drug driving, high risk missing person reports and associated multi-agency searches may have been avoided.
“Individuals may be going home safely to their friends and families who may not have been had we not closed the event down.
“None of what we do is about needless fun ruining.”