Six Mile Creek offers some of Ithaca's best hiking opportunities, with possibilities ranging from short walks to full day hikes.  Starting closest to downtown, the gorge can be entered from the Columbia/Giles end of the pedestrian bridge that crosses from Quarry/Ferris (bridge is the orange line on the map below).  The trail here follows creekside ledge in places, and can be submerged if water levels are very high.  Approaching Giles Street, the trail forks, with a dead end branch heading to the base of the falls below Giles Street, and the other branch climbing to meet the road.

From Giles Street, one can walk upstream on either side of the creek.  On the southwest side, walk around the fenced holding pond and you'll find trails continuing upstream.  On the northeast side, there's a parking area and a wide, well-maintained trail heading upstream.  Further uphill on Giles Street toward Route 79, there's another entrance to the wilderflower preserve.  From this upper trail (which is wide as a road), one can eventually fork back down to the creekside trail, or continue on the high road and wind up above the first reservoir.  From the northeast-side creekside trail (the one from the parking lot) one can continue to a point near the first reservoir dam, and then turn around, or take a fork that climbs steeply up to the level of the reservoir and connects to trails that continue around the reservoir.

An access point near the first reservoir is available from the Commonland neighborhood.  Look for the trail that heads back between townhouses.  Trails are on both sides of the first reservoir, though there's no convenient place to cross from one side to the other in this area.  On the southwest side, trails connect to the South Hill Recreation Way.  Trails on both sides continue past the first reservoir toward the second reservoir.  This is a particularly beautiful section of gorge that is loaded with trilliums in the spring.  Be aware though, if you plan to come here on a nice warm day, that the section of gorge between the first and second reservoirs is an unofficial nudist area (utilized primarily by men).

Access to the second reservoir is restricted, so you're not supposed to proceed past the dam at the bottom of this reservoir.  This is where Ithaca gets its drinking water.  It seems like people sometimes use the drive from Route 79 to the second reservoir for foot access to the gorge below, although "no tresspassing" signs are present there.

Links for Six Mile Creek Gorge and Mulholland Wildflower Preserve
http://ludlow.dns2go.com/cribbage/areas/6mile/6mile.html
http://www.footprintpress.com/Waterfalls/pottersfalls.htm
http://images.beggerlybend.com/photos/gorges/sm/index.html
 

Map courtesy of Tompkins County GIS