IT might be called trickle-down federalism, but what's trickling down are the obligations, minus the dollars to meet them. At least that's how many county executives across the United States tend to view their fiscal problems. The country includes more than 3,000 counties, and a high percentage of them - especially the most populous ones - are weighed down by deficits. The 443 largest counties in the US have shortfalls that average $8.3 million, according to a recent survey by the National Association ofCounties. If you ask the people who run these crucial units of local government why their budgets are blown, they're likely to point to the statehouse or Congress. Special education, clean water, health and welfare services, corrections, landfill reclamation - these are only some of the bigger items on a list of programs that have been piled on the shoulders of county officials. As the federal government strained to meet its tighter budgets, big areas of responsibility, like medical care for the poor, were increasingly pushed onto the states. And the states, facing shrinking revenues and budget gaps of their own, are doing the counties the same favor. The counties, however, have typically far less leeway than either states or Washington to come up with new ways of enriching their coffers. The recession has shrunk sales-tax revenue, and local constituents are likely to bridle at any hike in property taxes. Some officials are asking their state legislatures to approve new fees for county services. Like their colleagues at other levels of government, those who run counties are finding they have no choice but to cut programs. When the program is something as personally important as special education, the impact on families can be great. The counties' fiscal dilemma - like that at the federal and state levels - urges a hard look at national priorities. If counties are going to be given greater responsibility for important services, they ought to be given the resources to carry them out, too. At the least, they ought to be consulted about the realistic cost of such services, as well as the human costs of curtailing them. County officials, unlike others, can answer those questions.