Hartland, CT

Here is a map showing the protected open space in Hartland.  The vast majority of this land is owned by the Metropolitan District Commision (the land around the reservoir) and the Department of Energy and Environmental Protection (Tunxis State Forest).

Tunxis State Forest - DEEP does not seem to have a page for this forest other than a letterbox page. The following trails are within Tunxis State Forest.
CFPA Tunxis Trail (interactive map) - I'm not the biggest fan of the interactive map.  I do recommend using the CT Walkbook, but you almost need two - the 20th Edition printed in 2017 and the East and West books printed in 2005/6.  The detailed trail descriptions have been removed in the 2017 Edition.
Another resource for this area is OpenStreetMap.  Parking at the northern terminus of the trail is either in Massachusetts (according to CFPA) or you can park in a little lot at the end of the paved East Pell Road.  I do not recommend traveling by car on Pell Road.
There is also a campsite at Hurricane Brook.  Here is the page listing the campsites and how to apply for a permit.
CFPA Falls Brook Trail (see interactive map above) OpenStreetMap  - Steve Wood also offers a good description of his hike there.  More information on New England Waterfalls.

Horace Clark Woods maintained by the New England Forestry Foundation.  I recently (May 2020) went up to check these trails out.  Unfortunately, it does not look like they have been maintained.  I can see blazes on the trees, but no real trails.