WITH ALL THE public splash of a sand flea diving into a pond, the latest bulletin on the D.C. congressional representation amendment has arrived from the great state of Oregon, and the news is good: with an impressive bipartisan effort, Oregon has become the 10th state of ratify the D.C. amendment. This, coming after a bit of a dry spell on the ratification front, should reinvigorate efforts around the country to win over the requisite number of states.

All right, you had to ask: the amendment still needs approvals of 28 more states in the next 3 1/2 years. But take heart and prepare for a new set of campaigns to take the District's case to the states. The Coalition for D.C. Self-Determination, though short of help and money, continues to enlist the understanding and legislative support of a broad spectrum of sympathic Americans coast to coast.

The Oregon drive is a good example: approval there came with the help of an Oregon Coalition for D.C., headed by Ellen Bombalski, a leader in the League of Women Voters; Republican Gov. Victor Atiyeh; House Majority Leader and sponser Gratten Kerans; former vice president Mondale, whose personal commitment to the District remains strong; and various interested citizens groups.

Once people learn that their fellow citizens who live in the District of Columbia are totally unrepresented when the House and Senate vote on any matter before them -- budgets, taxes, the draft or even a war -- the simple justice of the amendment generally comes clear. The job then is to make it clear to state legislators that this should not be treated as just another piece of partisan or liberal-vs.-conservative politics, and that the District is not just an enclave of temporary and permanent residents living off the federal government. Thoughtful people of all parties, colors and walks of life have recognized for some 205 years now that there's something undemocratic about taxation without representation.

So the campaigns continue. In Maine, the amendment failed last time by one vote in the state senate; and other states, discussions with legislators are generating some additional support. Here at home, residents can help too: coalition workers welcome any volunteers and/or financial assistance to strengthen the informational campaign around the country. Whatever the outcome, ratification should not be left to fail by default.