I need the names of all golf courses that have caused groundwater contamination.

That could be a difficult question to answer if I interpret it correctly.  
There are many forms of groundwater contamination, some of which are
stringently regulated and others less so or not at all.

For known hazardous chemical contamination you could use the USEPA site 
http://www.epa.gov/enviro/html/em/
Enviromapper or Envirofacts would probably be most helpful.  If you
are interested in a specific state or local area only, contact your
local or state environmental agency or local health department.

The most common form of groundwater contamination resulting from golf
courses results from the application of fertilizers and pesticides. 
The commercially available forms of these are approved by the USEPA
and considered 'safe' for normal application.  In any case, inorganic
and even organic fertilizers can create high nitrate content in soil,
runoff waters, and groundwater.  High nitrate levels are a common
problem in most urban areas from residential use of fertilizers on
lawns.  High nitrates lead to 'blue baby' syndrome if the water is
used for drinking.  Some golf courses and some farmers are committing
to more judicious use of fertilizers and pesticides to protect waters
and wildlife as well as saving money.  Hope this helps.