Probably to make sure that each has there designated amount of water as rain only covers the surface.

My city does. Sometimes it’s very purposeful to reduce the water levels in the retention ponds/lakes. The pond water is used to water the city’s common lawns, plants, and golf courses. If the water level starts to get very high from rains, the city turns on the irrigation and waters the common area to bring down the water level in the ponds so there isn’t any flooding. Sometimes, they are running the irrigation even while it’s still raining.

People get paid to do a job, rain or shine, so there is that…
And, to properly water some plants, you gotta water ‘em good! I don’t know how many dead trees on city property that were given insufficient water when and after they were planted, and they died.

But it’s even when it’s pouring rain, @Inspired_2write re. ”...amount of water as rain only covers the surface” and @kritiper re.“on city property that were given insufficient water.”
BTW, @JLeslie re. ” the city turns on the irrigation and waters the common area to bring down the water level in the ponds so there isn’t any flooding, I’m referring to watering plants by trucks.

@flo Oh, I hadn’t understood it was with trucks. I don’t know about that. Seems like a waste, unless the goal is to move the water around, but they could dump the water almost anywhere then, assuming it doesn’t roll right back into the lakes they are trying to control, if there are bodies of what they are trying to control? Maybe the union is very strong, and it’s protecting the employees’ hours?

@flo “Even when it’s pouring rain,” sometimes it isn’t enough to really soak the roots.
The guys who drive the trucks need to get in their 40 hours a week and if it’s their job to water, then, rain or sun, whatever, they water. And they may belong to a union…
Where I live, there may be a ton of water comes down with the rain in one part of town while the other parts may get little or none. So how would the guy in the truck know if he was needed everywhere, or just in some places? Better that he just water everywhere and be certain. The city has too much money tied up in that grass and those trees to just chance them not getting enough and dying.

@JLeslie But even if the employees are guaranteed their hours or something like that, the employees can do nothing (or do something else?) when it’s almost flood level of rainfall. I don’t think the public would complain about that. And wouldn’t the union want that too?

..And how often does it happen that the scheduled day for watering plants and heavy rainfall days coincide?

@flo What you said makes sense to me, why use the gas, and why make them do the physical work and be out in bad weather if it’s not doing any good? Maybe it is doing some good we don’t realize though.

Seems like if it’s not helping water levels or the plants, and the union has some sort of stronghold, that they could have the truck drivers help in some other community way. Maybe help paint schools, or help at a local public hospital or something.

@JLeslie ”...why use the gas, ...” I didn’t even think of the gas.