On Sat, 29 Jun 2013 04:01:41 +0000 (UTC), "Danny D."
wrote:

Also, I can't tell if there is a pressure regulator on the
valve itself, as it might be buried, for all I know.

I don't know the valve brand, but *generally* speaking, the various
ones I've worked with can be adjusted to reduce pressure on the lines.

See step 2: (Adjust to a Lower Setting)

See step 3: (Adjust the Sprinkler Valve) drip lines in your case.

http://www.doityourself.com/stry/how-to-adjust-a-sprinkler-valve#.Uc78Rx7n-1s