Huge amount of light green mucus completely coating only one nostril twice a day. what could it be? thanks!

Not fully understood: Your description isn't fully understood, however, it may be upper respiratory tract infection with discharge from one nostril.Rhino-sinusitis, can be acute or chronic,you need to be seen and prescribed antibiotics if needed, meanwhile you may want to irrigate your nasal passages with salt water, that would help reduce the inflammation and wash out the discharge, till seen by your doctor, goodluck