From the actual movie script, not a secondary source:
FADE IN:
1 EXT. DESERT - DAY 1
Shimmering waves of heat. A flat unforgiving landscape
stretches to infinity. A storm of dust gathers on the
horizon, small at first, increasing in size as it
rolls toward us. Hoofbeats fill the soundtrack. Just
as the storm threatens to engulf us, A RIDER ON
HORSEBACK emerges.
Superimpose: NIMBUS III
IN THE NEUTRAL ZONE
("THE PLANET OF GALACTIC PEACE")
2 CLOSER ANGLE - STRANGE HORSE AND RIDER 2
A twisted rhino horn juts from the snout of this odd
creature. The Rider spurs the beast, driving it onward.
His white robes flare out behind him like the wings
of an avenging angel. He rides like a man possessed.
CUT TO:
3 EXT. DRY LAKE BED - DAY 3
Camera pans an arid expanse of scorched earth. J'ONN,
a ragged and malnourished homesteader of some alien
race, toils beneath a blazing sun, his back to camera.
He sinks an augering device into the ground, drilling
in vain for water. There are many hundreds
of holes in the earth around him.
J'onn reacts to the clop of approaching hooves. He
tenses, then whirls around clutching a crude home-made
pipe gun.
He sinks an augering device into the ground, drilling in vain for water.
This is the Revised Final Script dated November 21, 1988, with a foreword by Producer Harve Bennett. The original script can be purchased from the genuine Roddenberry family company.
This is backed up by another, highly trusted source, Chakoteya.net:
(out of a dust storm a horseman approaches an alien drilling for water. The horseman dismounts and addresses the alien)