In Italy, data are not available on the morbidity associated with drowning.
However, national mortality data available from the Italian Institute of Statistics (ISTAT) permit an evaluation in trends and characteristics associated with drowning deaths for 1969 to 1998, the most recent year for which data are available.
For purposes of this analysis, those deaths with an ICD-9 code of E910 were identified. Additionally, those with the codes E830-E838, which refer to deaths secondary to injury sustained during water transport, were included in the analysis.
http://www.worldlifeexpectancy.com/cause-of-death/drownings/by-country/ Italy 1.63 per 100,000 die from drowning. Their national website is now down (satguru).
Interesting question since Venice itself is considered to be "drowning"!
The data I saw was regional, not specific to Venice or any other city, and there appears to be a time lag of four years in its gathering and analysis. Perhaps Venice keeps its own statistics on drownings as it would seem to be a hazard peculiar to its environment!