The emergency services were called out to Daventry Country Park on Sunday after two people got stuck in water and mud.
The alarm was raised at midday, and police, fire, ambulance and the air ambulance were all called out.
An adult an child had become stuck towards the southern end of the park, between the scout hut and underpass to the iCon.
The fire service used a thow line to get the adult free, while the child was talked through freeing themselves.
In August two children got stuck in mud near to the visitors’ centre after it was uncovered by the low water in the reservoir.