Hello, Kyle. Thank you for using Ask an Expert for help with your arborvitae.

Because of the uniform position of the damage, I believe that your deer theory is correct. The Emerald Green variety of arborvitae is (scientifically speaking) Thuja occidentalis—American arborvitae. This species of arborvitae is rated quite susceptible to deer damage. The other species, Thuja plicata—Western arborvitae—is more resistant to deer, though not highly resistant.

Planting “more resistant” shrubs is clearly not an option for you. I would recommend trying the deer repellant products on the market. These need to be applied as directed on the label, consistently, and usually again after a rain. This US Forest Service comparison of products was done in Washington State some time ago, so the exact products may not be available, though others with similar ingredients may be. No repellant is 100% effective and, if hungry enough, deer will eat most anything.

There are also light, sound, and water “scare” products available. I have no information on their effectiveness.

Have a good gardening year,