Saint-Gaudens NHS is bordered on two sides by the Blow-Me-Up Brook and the Blow-Me-Down Brook.  Both brooks travel through upland forest habitat before merging and traveling to the Connecticut River.  As they pass through the park their waters are joined by the waters of several seep springs, leftover remnants of glacier activity in the area.  Signs of past glaciation can be seen by observing the roundness of hilltops and the smoothness of rocks and boulders near the brooks and scattered throughout the landscape.  Signs of the past can also be seen at the Blow-Me-Down Pond, where the old grist mill sits empty near the dam, which once powered the mill operations.  The mill was operational from 1891 until 1918, when it closed down.  The pond also has a boardwalk on its east bank; from here the pond wildlife can be quietly observed.