Well this thoroughly sucks but FYI....
Lot of people have ridden Miner's Ridge trail at Black Mountain. The name for the trail was derived from the Arsenic Mines directly below it. There is a good history write up all over the web if you want to know more. Problem is there is a very high concentration of arsenic at the ground level along several sections of the trail. Having seen the problems with lack of action (think Flint Michigan), the city has decided to close the lower portion of Miner's Ridge from the parking lot to the Night Hawk connector. You can still get across the mountain using the upper portion of the Miner's Ridge trail but will have to descend on the Glider Point Trail.
Nobody knows the time frame for testing of the soil but for now, please observer the trail closures for now. For those of you who know me, this is not a bullshit, trail closed for no reason type of post. It is a potential health hazard that needs to be avoided. We have know that there were higher levels of arsenic for some time but a geology grad student from SDSU discovered the levels were off the charts in certain areas along the trail. I very much believe that the problem will prove to be over blown but for now, please work with the closure.
Official City Press Release
Map showing closure and alternative route
The whole event is very fluid right now. The City Attorney and Mayor's office ordered the closure. When more information comes to light, including time table for testing, I will post them here. There is also up to date info on the SDMBA Facebook page too.