If it was a natural spring then you could make a feature of it, otherwise i would be tempted to pipe it to a soakaway, an open ditch will attract rats unless it has a very good flow.
Could be a natural spring.
When i was young, my sister and myself would walk around the garden impaling slugs on bamboo cane and see who could get the most, very satisfying.
Well it says on the label Salvia sclarea turkestanica Alba.
Tis a salvia i`m sure, i bought one from a gc early this year, think i still have the label, here`s mine.
Have you thought about playing "whitenoise" against the fence? it is supposed to block noise by absorbing the sound.
We have a 9 month old English springer spaniel called Mistletoe aka Misty or moo moo, she`s the reason for the green netting around the flower beds. Her tail has not been docked and she`s not being gun trained
Don`t bother with landscaping maintenance firms as you`ll learn nothing, i find using google for gardening jobs or horticulture is very good, make your cv as best as it can be and good luck.
If you like it, keep it. It`s your garden after all and try not to listen to those unhelpful "experts" ^^