Rick,
Depending upon weather you have Fines, or Talls, or a mixture of both, a very simple and inexpensive solution to this is to apply rock salt to these areas. The rock salt will kill fescue that it touches, thinning and making these areas much more playable. I have seen this done at several high-end properties in the Mid-Atlantic, and in the Northeast. Just be mindful of drain basins, drainage areas, etc., so that the product does not leach into normal playable rough.
We have done this in 20' swaths along regular rough, and it has proved quite beneficial, as we encountered the same issue...that along with irrigation adjustments to take all irrigation that may be hitting these natives away. That will also obviously help thin the areas.
If you have any questions, feel free to drop me a line or email. Best of luck!
Regards,
Ross Miller
Golf Course Superintendent, Championship Course
Trump National Golf Club, Washington DC
419-410-7326 (Mobile)
rmiller@trumpnational.com