Confluence has its issues, but its a good spot!
I'll defend the honor of Confluence Park and the South Platte.
Every major river in colorado has treated sewage in it.
Golden is downstream from Central city, blackhawk, Idaho springs, georgetown, lawson, dumont etc... In some rivers there is a significant amount of agricultural and mining runoff too.
What really affects the South PLatte is untreated stormwater. On days like today there is no stormwater runoff into the river about 75% of the water is coming straight out of chatfield.
So here are some pros and cons for boating Confluence and the South platte. Pros:
1) Warm water
3) No lines in the eddies
4) lots of different features at different water levels.
1) Water quality can be an issue - save your drinking for the Bar!
2) You'll want to rinse off your gear and yourself
3) On warm days there may be lots of people swimming & tubing
Anyway, many of the people who carp about Confluence do not boat there. I have boated there since 1987. The water quality is better than it used to be. It is a good place to build your skills, as are all of the other parks....