I haven't done this course before and I'm not familiar with the area, so those that are please corret me if I'm wrong.
But by tracking the elevation profile along with the actual satellite imagery of the run course itself, it appears that the elevations drops/climbs shown just before mile 4, and at mile 6, 10, and 12 are associated with bridge crossings over the river. These elevation maps are generated using ground topography, not road elevation. So the elevation losses/gains at those points are likely coming down off the floodplain/bluff to the actual river water elevation, then back up the bluff. The actual road elevation is probably relatively consistent at these points connecting the higher elevations on either side of the river. So that makes the elevation gain for the run significantly less than it appears on the elevation profile (~300 ft less).
But by tracking the elevation profile along with the actual satellite imagery of the run course itself, it appears that the elevations drops/climbs shown just before mile 4, and at mile 6, 10, and 12 are associated with bridge crossings over the river. These elevation maps are generated using ground topography, not road elevation. So the elevation losses/gains at those points are likely coming down off the floodplain/bluff to the actual river water elevation, then back up the bluff. The actual road elevation is probably relatively consistent at these points connecting the higher elevations on either side of the river. So that makes the elevation gain for the run significantly less than it appears on the elevation profile (~300 ft less).