I have a small outdoor fountain in my backyard, that uses a small
pump. The pump has an electrical cord that I plug into a heavy duty
extension cord, which goes into an electrical outlet mounted on the
outside of my house. (The outlet has a cover, so it is protected from
water. Furthermore, I presume that this outlet is on a GFCI circuit.)

My question is: the pump cord is plugged into the extension cord, and
is just lying on the ground. How do I protect this connection from
water (garden sprinklers, rain)? Does it need to be protected? Are
there products I can buy to encase this connection?

Also, I'd like to have a switch to turn on and off the pump (the pump
itself has no on/off switch -- it's always on when plugged in).
Ideally, I'd like to find something that would both protect this
connection and include a power switch, for outdoor, waterproof use.

Hi Bay,

Yep. It costs about 3 bucks from your local hardware store. Yellow
(for safety) made from plastic material. It's sausage shaped with one
length hinged, the other side is snap locked. Baffles hold both cord
ends in place. This stops the cords from being pulled apart also.
However, this is meant as a temporary measure when using power tools
with an extension cord.

As your water fountain is a permanent feature, consider running the
cords underground in PVC conduit. Better still, do it properly and
have it hard wired in. Your electrician can then install your second
switch at the same time. If too expensive, you might have to put up
with using the one on the wall. To overcome this, just plug in a
timer.

Your home insurance probably won't cover your visitors from
electrocution due to exposed power cords. Water and power cords don't
mix well.

Good luck.

Except for temporary wiring (as provided for in the National
Electrical Code, NFPA-70/NEC-305, not to exceed 90 days) cord-and-plug
connection of equipment is not permitted to be energized from
extension cords.

FYI: Unless you have a special cover plate for your outdoor outlet,
most outdoor weatherproof covers are only certified weatherproof when
it's closed (read the fine print on the product). There are
specialized hoods which can be purchased that are rated weatherproof
even while in use.

Most insurance coverage (homeowners, personal liability, etc) have
exclusion clauses for damages caused by or from electrical systems not
in compliance with NEC code.

To answer your question about GFCI outlets outside, NEC didn't require
it until 1973. Of course, that doesn't mean your ESA (Electrical
Safety Authority) implemented the 1973 revision to NEC on that same
year.

Basically, I would only recommend hiring someone to do the electrical
work for you, done to code. That way you can also use a switch or even
a photo-electric sensor, so that it turns on/off at night or day
(whatever you choose).