diff --git a/pyschism/forcing/source_sink/nwm.py b/pyschism/forcing/source_sink/nwm.py
index 7c15a55f..947f0ecf 100644
--- a/pyschism/forcing/source_sink/nwm.py
+++ b/pyschism/forcing/source_sink/nwm.py
@@ -113,38 +113,45 @@ def __init__(self, hgrid: Gr3, nwm_file=None, workers=-1):
             raise IOError(
                 "No National Water model intersections found on the mesh.")
         intersection = gpd.GeoDataFrame(data, crs=hgrid.crs)
-        #TODO: add exporting intersection as an option
+        #export intersection to a file
         #intersection.to_file('intersections.shp')
         del data
 
-        # 2) Generate element centroid KDTree
-        centroids = []
-        for element in hgrid.elements.elements.values():
-            cent = LinearRing(
-                hgrid.nodes.coord[list(
-                    map(hgrid.nodes.get_index_by_id, element))]
-            ).centroid
-            centroids.append((cent.x, cent.y))
-        tree = cKDTree(centroids)
-        del centroids
-
-        # 3) Match reach/boundary intersection to nearest element centroid
-        coords = [
-            np.array(inters.geometry.coords) for inters in intersection.itertuples()
-        ]
-        _, idxs = tree.query(np.vstack(coords), workers=workers)
-        del tree
-
-        logger.info(
-            "Pairing features to corresponding element took " f"{time()-start}."
-        )
+        #TODO:intead of creating a gdf for all elements, only create for nearest elements and its neighbors
+        buffered_geometry = self.hgrid.elements.gdf.geometry.buffer(0.0001)
+        elements_gdf = self.hgrid.elements.gdf.copy()
+        elements_gdf['geometry'] = buffered_geometry
+        joined_gdf = gpd.sjoin(intersection, elements_gdf, how="inner", predicate="intersects")
+        point_element_ids = joined_gdf.index_right.values.astype(int)
+
+        ## 2) Generate element centroid KDTree
+        #centroids = []
+        #for element in hgrid.elements.elements.values():
+        #    cent = LinearRing(
+        #        hgrid.nodes.coord[list(
+        #            map(hgrid.nodes.get_index_by_id, element))]
+        #    ).centroid
+        #    centroids.append((cent.x, cent.y))
+        #tree = cKDTree(centroids)
+        #del centroids
+
+        ## 3) Match reach/boundary intersection to nearest element centroid
+        #coords = [
+        #    np.array(inters.geometry.coords) for inters in intersection.itertuples()
+        #]
+        #_, idxs = tree.query(np.vstack(coords), workers=workers)
+        #del tree
+
+        #logger.info(
+        #    "Pairing features to corresponding element took " f"{time()-start}."
+        #)
 
         hull = hgrid.hull.multipolygon()
 
         start = time()
         sources = defaultdict(list)
         sinks = defaultdict(list)
-        for row in intersection.itertuples():
+        for idx, row in enumerate(intersection.itertuples()):
             poi = row.geometry
             reach = reaches.iloc[row.reachIndex].geometry
             if not isinstance(reach, LineString):
@@ -157,15 +164,18 @@ def __init__(self, hgrid: Gr3, nwm_file=None, workers=-1):
                     d1 = segment_origin.distance(poi)
                     downstream = segment.interpolate(
                         d1 + np.finfo(np.float32).eps)
-                    element = hgrid.elements.gdf.iloc[idxs[row.Index]]
+                    #element = hgrid.elements.gdf.iloc[idxs[row.Index]]
+                    element = point_element_ids[idx] + 1
                     if (
                         box(*LineString([poi, downstream]).bounds)
                         .intersection(hull)
                         .intersects(downstream)
                     ):
-                        sources[element.id].append(reaches.iloc[row.reachIndex].feature_id)
+                        #sources[element.id].append(reaches.iloc[row.reachIndex].feature_id)
+                        sources[str(element)].append(reaches.iloc[row.reachIndex].feature_id)
                     else:
-                        sinks[element.id].append(reaches.iloc[row.reachIndex].feature_id)
+                        #sinks[element.id].append(reaches.iloc[row.reachIndex].feature_id)
+                        sinks[str(element)].append(reaches.iloc[row.reachIndex].feature_id)
                     break
 
         logger.info(