How can I alleviate allergy symptoms (watery eyes, runny nose, clogged ears, sneezing)?

Many ways. The most common answer you will get from docs is "allergy meds". In addition, avoidance of the allergens is a powerful solution, but often difficult to achieve. Rinsing away those allergens from your nose can be hugely successful. Consider using a daily nasal rinse of saline. Like rinsing dust off your car, daily nasal saline rinses wash away allergens, virus, bacteria. Nice effect. Try it.
Eye Drops. Seasonal allergies are a real drag. I think an all out "no prisoners" approach is best. Follow the guidelines of dr. Faust ENT and use nasal sprays, additionally there are now very good eye drops called mast cell stabilizers that prevent the histamine from ever releasing from the surface of the eye. These are a prescription once a day eye drop and bring real relief after about 2-3 days of use.