var layer1 = L.tileLayer.wms('http://localhost:8080/geoserver/wms?', {
    layers:'topp:states',
    format: 'image/png',
    transparent: false,
}).addTo(map)

http://localhost:8080/geoserver/wms?&service=WMS&request=GetMap&layers=topp%3Astates&styles=&format=image%2Fpng&transparent=false&version=1.1.1&height=256&width=256&srs=EPSG%3A3857&bbox=-11271098.44281895,5009377.085697314,-10644926.307106787,5635549.221409476

var splitLink = bareLink.split("layers=");
      var splitLink2 = splitLink[1];
      var i = 0;
      while(splitLink2 != "="){
         result += splitLink2.charAt(i);
          i++;
          if(splitLink2.charAt(i) == "&")
              break;
      }
      finalResult = result.replace(/%3A/g, ":");

var ACTIVEOVERLAY = finalResult;
var CQLFILTER = <determined by map seleciton>

var layer1 = L.tileLayer.wms('http://localhost:8080/geoserver/wms?', {
    layers: ACTIVEOVERLAY,   <------------
    format: 'image/png',
    transparent: false,
    CQL_FILTER = .......   <-------------
}).addTo(map)