A jet ski rider has been caught travelling along the River Murray while under the influence of methamphetamines, South Australian police say.

The 29-year-old man from Angle Vale in Adelaide's north allegedly returned a positive drug test when he was stopped by a river patrol at Cadell on New Year's Day.

Another test was conducted at the Berri police station which police say confirmed the original one.

It is the first positive reading in 93 drug tests on the river since Boxing Day.

The man will appear in the Berri Magistrates Court at a later date.