In Ontario, there are 1.25 people per 100,000 that die every year due to drowning (as per the Ontario Life Saving report found here: http://www.lifesaving.ca/wp-content/uploads/2013/09/Ontario-Drowning-Report-2016.pdf) which means that in a city the size of Cambridge, you have between 1 and 2 people that drown every year. If you look at the statistics, since 1990, the numbers are declining slowly (from 685 in 1993 to the lowest year, 433 in 2004 to the current stats for last year of 466), a decline of 32% in 20 years.

Here's the point and it is called the law of diminishing returns. No matter what you do, you will never get that number to zero, ever. And the cost to get it to zero is very high, and for a reduced segment of the population like those with autism, at 2.83% for boys and 0.53% for girls (https://www.autismspeaks.org/what-autism/prevalence), it will be practically infinite. Any difficulty where a person has free will has the same problem. Money is not the answer.