Algae issue

I have a couple underground springs that surface in my yard that I dug out into and ornamental running "pond" that exits into a drainage system

It looks nice and it stopped the water from backing up into the rest of my yard, but its not an actual pond, the water runs straight through left and top to right in the attached picture.

Only issue I have is that algae keeps building up in the water, every few days I go out and skim it clean.

anything I can do to prevent this? i would prefer not to use chemicals and I think they would just wash through into the drainage pipe anyway.

Any advice is appreciated,

Thanks

Since the source of nutrients feeding this algae growth is the source water (springs)and this is a flow-trough system, there is really not a lot that can be done.
You could convert this into a Rain Garden.