Kriging with barriers in ArcGIS Desktop?

I am trying to do interpolation in a coastal area with data points in several rivers emptying into a bay and on opposite sides of peninsulas.

I have created a coastline layer to use it as a barrier but cannot figure out how to do this in ArcGIS 10.

I do not see a barriers object anywhere in any of the kriging tools.

I tried just doing the kriging then clipping it to the land, but I get unrealistic results where data points close together but separated by land create problems.

I see online documentation for doing this in geoprocessing scripts in 9.3 but nothing similar for 10.