Police have arrested 55 people across Kent in a fortnight-long clampdown on drug dealing and use.
Officers detained an 18-year-old man in Canterbury after they saw him acting suspiciously trying to throw packets into the River Stour.
They retrieved the items and found them to contain heroin and cocaine.
He has been released pending further inquiries.
Officers have also seized drugs, cash and mobile from other people believed to be peddling illegal substances in Kent.
Much of the dealing of hard drugs on Canterbury’s streets is organised by London gangs who send young men into provincial towns and cities to ply their trade in an activity known as “going country”.
Det Ch Insp David Coleman said: “Criminals involved in the sale of class A drugs are ruthless and often commit other serious offences against drug users, rival dealers or innocent members of the public with knives and other weapons.
“Many also have links to criminal networks in London and we regularly plan operations such as this in order to send a loud and clear message that they are not welcome in Kent and we will not tolerate the supply of class A drugs on our streets.
“Our operation continues to yield some excellent results and we hope our enquiries into those arrested will see a significant number of them being brought before the courts.
“We continue to rely heavily on the general public to make us aware of who is dealing drugs and where, so we urge people to continue to report any suspicious behaviour.
“By continuing to work together we not only ensure Kent remains a safe place to live, work and visit but we also reinforce the message to criminals that there is no hiding place from the law.”