Leanne Gordon, 30, of Bedford, died in July after she waded into the Great Ouse in the town with three children.
Ms Gordon, who had signs of cannabis in her system, got into difficulty and her body was found the next day, Ampthill Coroners' Court was told.
Coroner Tom Osborne recorded a verdict of death by "misadventure".
There had been reports at the time of Ms Gordon's death that she was in the water after a child got into trouble but this was still unclear, Mr Osborne said.
He said excessive alcohol would have hampered her attempts to get out of the water close to Honey Hill Road on 21 July.
Mr Osborne called her death "tragic", stressed he was not critical of her drinking alcohol that day and expressed his condolences to her family and friends.
A post-mortem examination found a high level of alcohol in her blood.
The pathologist said she would have consumed an "appreciable amount" of alcohol and also noted she had either used or been exposed to cannabis before her death.
The inquest heard she was on medication for heart palpitations, panic attacks and asthma.
After the inquest, friend Tasha Filby said Ms Gordon would be remembered as "outstanding".
Ms Filby said: "She was vibrant, extremely colourful, caring, hard-working, passionate and above all a fantastic mother who was so passionate about her children and so good with them."
A mother who drowned on a visit to the river with her family was more than three times over the drink-drive limit, an inquest has heard.