I thought that Santee had a group of 7 lakes that were originally a water purification system. Imagine my surprise walking 8 months AFTER this article was first written, and finding 3 more lakes upstream of the public 7. I now say there are 10.
Read on!

Santee is just upstream from Kumeyaay Lake along the San Diego River.

The bottom 5 Lakes form a nice park for day recreation,
while there is a deluxe RV park and campground around the top two lakes.

The lakes are each a pleasant stroll-around size.

One unusual feature is a huge roadway bridge that goes right across one of the lakes.

I found the ripples in the water form interesting patterns on the bridge.

It's a very nice place to spend a few hours.

Eight months later:
Here is the map showing today's drive and walk, and three more bodies of water.

The utility towers and wires cross the lakes 

These ponds are part of the water filtration system for Santee

It's not easy to see the ponds from the path we were on, 
but there's another path on the south side as well.

A group of wasps were busily working this flowering fennel plant