I figure there's some Lake Walter E. Long (aka Decker Lake) stakeholders on this forum. The city of Austin is putting together a master plan for the lake and they've narrowed down the general frameworks to four. Two of the four involve letting the lake dry up.
If you've got an interest in this issue, the city is soliciting feedback through this survey: https://www.surveymonkey.com/r/WELArrange
All of the plans involve adding hiking trails and park amenities which are badly needed. But here's a rundown of the major differences:
Plan 1: keep the lake and most of the natural areas around it
Plan 2: keep the lake but put a golf course where there's currently a forest
Plan 3A: lose the lake, turn the dry lake bed into park stuff
Plan 3B: lose the lake and put the golf course in the old lake bed
Now, I fish at Lake Long a lot. But after the power plant shuts down in the near future, it's primary function as cooling water goes away. The current lake level is maintained by pumping water up from the Colorado River. When I was at the community meeting they didn't have any hard numbers for how expensive it is to maintain the lake.