For Arc/Info users, the ERASE command uses the polygons of one coverage to remove corresponding features from another coverage. Use ERASE to remove those trap sites from the "proj_sites" point coverage, which fall into Smith Mountain Lake. Name the resulting coverage "sites_final"

Arc: erase

Usage: ERASE <in_cover> <erase_cover> <out_cover>

{POLY | LINE | POINT | NET | LINK | RAW} {fuzzy_tolerance}

Arc: erase proj_sites sm_mtn_lake sites_final point

Erasing proj_sites with sm_mtn_lake to create sites_final

Overlaying points...

Creating sites_final.PAT...

Arc: build sites_final point

Building points...

Arc:

Use ArcPlot or ArcEdit to examine "sites_final" with "sm_mtn_lake" as a background. Note that four traps we eliminated; all remaining traps are land-based.