I started looking into what was down there several years ago and really did not come up with much. The "forest" is managed under an umbrella of government agencies federal, state, county, city. There is not alot of cross talk between them and their underlying goals seem to differ. The Corps of Engineers seems to take precedent over all others since their responsibility is flood protection, levees, the waterway and engineering. The alphabet soup of agencies seem to tie each other in knots.
In addition to government agencies a number of non-profit groups run nature centers, trail construction and activities in the area. The Dallas Audubon Center on Loop 12, The Texas Horse Park on Elam Road both are making substantial investments for the future in this area.
For more information visit their websites:
The non-profit responsible for quite a bit of soft surface/natural surface construction in the Great Trinity Forest is a group called Groundwork Dallas. They have built a number of miles of soft surface trail in the White Rock Valley south of Scyene Road and north of Hwy 175. They have also built trails in the Rochester Park area south of 175 and east of the Hwy 310 bridge.
They have built some exceptional trails in Dallas over the last several years.
I have often wondered why I never see others out on these trails. They are in the middle of the city, have some amazing views. I have been asked numerous times where or how someone can get to the trails but cannot point them in the right direction. Hopefully I can add some of what I know or have stumbled upon myself.