Let's first make sure you have all 3 species in the pasture. Traps, toxicants, and potential monitoring/management can be very different for each of those. Could you please upload photos of undisturbed (i.e., pre-dog and pre-sheep interactions) sign that you're seeing? If there are above-ground mounds of dirt, it would really help (alot!) to get a photo of a fresh, pre-rained-on mound, too - Which, I realize, could be nearly impossible today, but perhaps tomorrow if we get a break in the precip?



I think perhaps we need more input from a pastures/forage agronomist. My expertise is wildlife ecology, so I advise on things like replanting to diminish food and thus carrying capacity for that particular species of animal, but it sounds like 1)trapping is not affordable/effective at the scale you're attempting to do so 2)the dogs are creating an additional hazard to the livestock and 3) there's no way to rebuild or replant the field. I have no expertise on how to fill/resurface your pasture short of using equipment to do so, and it sounds like if you were to passive/broadcast for some other plant species that would support fewer of whichever small mammal is making the holes of greatest damage (or interest to the digging dogs), that I wouldn't know what to have you plant that would be safe and sufficiently supportive of your sheep. As to simply leveling if you're talking (still unsure from what's provided) knocking down mounds from gophers or moles, perhaps just a manure drag behind an ATV? Would that work?

I’ve attached a few photos. We caught another gopher tonight. In the past the voles have been terrible but they aren’t so bad this year. Rather, it’s the gophers that are the worst and moles 2nd. It’s pretty clear we will have to haul dirt to fill the holes the dogs have dug, but the places where there are just a ton of holes are more difficult. We have a harrow and we can turn it around to serve as a drag, but lots of these holes are deep—leg breakers for stock and dogs. Maybe multiple harrow passes followed by a drag? I was hoping someone at extension might have some suggestions beyond what we’re thinking of. Please look your pastures/forage specialist in if you think they might be of help.

I would contact one or more of the pasture specialists linked to this page https://extension.oregonstate.edu/crop-production/pastures-forages/revitalizing-your-pastures-primer-overseeding-pastures-western about best choices for overseeding, etc.
From your photos, I see alot of vole activity, including vole burrows up through the mounds of either gopher or mole. There are registered, restricted-use products (primarily ZincPhosphide) that are labeled for in-burrow (i.e., hand-baiting) for both voles and gophers. Products such as zinc phosphide, strychnine, etc., are not species-specific -- So if you decided to treat the pasture prior to doing overseeding, you'd really want to be careful/thoughtful about allowing your other animals and stock access to prospective contact (inhalation or ingestion) of the bait or ingestion of animals containing the bait.
This is part of why these products are restricted access & use, which means you either have to have a pesticide applicator license (many farm owner-operators do), or need to contract with somebody who is licensed and thus able to purchase and apply those products. One subgroup of qualified applicators would be those who are also trained and licensed as Wildlife Control Operators, so you might contact one or more and request a free estimate: https://www.dfw.state.or.us/wildlife/license_permits_apps/wildlife_control_operator_contacts.asp



I share your concern with the toxins and non-target animals - both domestic and wild. I think discussing a rotation to a grain or something that lowers carrying capacity for the moles, voles, and gophers, may be a necessary step - It would take planning of course, because you'd need to plan for alternative pasturage, etc.