This severely underbirded area holds excellent potential in any season. There are two small ponds accessible by paths, two fairly large lakes, and a mix of 600 acres of various-aged woodland and 400 acres of old fields sown with native seeds to restore prairie and savanna communities. With the exception of the vicinity of Lake Walter, the Audrain County portion of the area is by far the easier to access.

From the parking area on CR 742 at the northwest corner of the area an old two-track trail leads through old field/grasslands and a bit of woods. Even a short walk here can produce a broad variety of species, especially in the grassland portion.

The northernmost parking area on CR 751 immediately past the small sign for the Martinsburg Community Cemetery gives access to a minimally maintained footpath/old two-track not marked on the area map that leads to a small pond.

If coming from the north, the first road to the left (east) into the area passes through rough grassland to a parking area with a cable-gated old two-track coming off it to the north that passes briefly along grassland (beware of poison ivy), then veers into woods. The pond is not easily accessed from this two-track. It can be reached from a path near the two-track’s “gate”, but rank vegetation makes this unappealing for most of the year. The minimally maintained track to the right off the lot goes through woods to Lake Whitesell, but there is no connection to the road into the lake.

The next road runs through a narrow grass/scrub alley to the two lakes. Note that at the fork, the road to the left leads to Lake Whitesell with all but the far left portion in Audrain Co., and shortly after the fork the right road enters Montgomery Co. on its way to Lake Walter. 

The lack of late autumn and few winter visits accounts for only three species of ducks on the site checklist. The two lakes should host several species. There is excellent habitat to support wintering sparrows. Limited spring reports show a very good variety of vireos and wood warblers using the site in migration and indicate a probability of a good showing of them in the fall. The two July reports available at this writing total more than 50 species—a clear indication of the richness of the mix of habitats to be birded.

If coming from the west, for Audrain Co. portion from Martinsburg, take Walnut St. (a.k.a. CR 751) south from the water tower to a right turn on CR 742 to reach the parking lot on the northwest corner, or continue on CR 751 to parking lots discussed below and the central portion. Continue south on the paved RA for additional lots in Audrain Co. and one in Montgomery Co.

If coming from the east, in Wellsville, from MO 19, take Rt. ZZ west/south 3 miles to a right onto RA to reach the southeast corner of the area in a quarter mile.

The area is named for Marshall I. Diggs, who donated 610 acres in 1958. The Wellsville Firebrick Company donated 160 acres. Funds from Mr. Diggs were used to bring the area to its present 1,017 acres.

A footpath (shown on the area map) takes off from the south end of the dam and gives access to creek bottom woods, but some bushwhacking may be needed to reach the Audrain Co. lot nearest the county line.

A trail is shown on the area map leading northeast from the Montgomery County lot on RA. As of summer, 2023, this was an unmaintained footpath through heavy grassland/scrub, that did not look inviting given the probability of ticks, chiggers, and poison ivy along its course.