Purgotary Cove and Forest Grove combine to be a nice part of the Charles River Walk along the Waltham-Newton line. It’s an area I have yet to explore fully, but seems to have quite a bit of potential.
To reach it, take Woerd Ave. off Crescent St. in Waltham. Follow Woerd Ave. to the end. You’ll pass the boat launch and then Purgatory Cove. You can pull over here or continue to the circle where the road ends and park there. The town line is just beyond the circle. Alternate access from the other end is off Commonwealth Ave. at Lyons Park.
Purgatory Cove is a large backwater spot along the Charles. It gets filled with vegetation in summer. Lots of waterbirds are possible here, including large numbers of Wood Ducks. Along the river on the other side of the road, you can follow a trail that winds through the wooded area and then joins the main Forest Grove trail. There’s a couple of steep spots here, so be careful.
Up on the main trail, you can walk through a wooded section that borders the river and passes through a couple parks before ending. Lots of birds are possible, including many migrants. This section is also the only place along the Charles where I’ve had Wild Turkeys.
Butterflies are not too exciting along here, but dragonflies can be interesting. The only Vesper Bluet I’ve seen so far was along the first bit of trail by Purgatory Cove. I haven’t spent enough time looking for other good ones, but I’m sure there are more out there.
This stretch of the river is also popular with boaters and kayakers. It’s very wide and slow and I’d imagine you can see quite a few different things on the water.
Well worth exploring more, there’s plenty of untapped potential here, even when the crowds are out.