Protection and Management Plan for the Millbrook Marsh Nature Center

wpe1.jpg (4948 bytes)

Stream Habitat and Discharge

In 1997, Slab Cabin Run averaged 5.5 m (18 ft) wide and 0.3 m (1 ft) deep. It consisted of approximately equal proportions of riffle, glide, and pool habitats (Table 8). Only 36% of the bank was rated as stable. Grave] was the predominant substrate and silt ranked second.

Table 8.  Summary of habitat composition in reaches of Slab Cabin Run and Thompson Run within Millbrook Marsh (File: MARSHMAP.WK4).

  % riffle % glide %pool % stable bank % bank fish cover % instream fish cover % substrate composition
boulder cobble gravel sand silt
Slab Cabin Run 27 38 35 36 32 21 6 11 42 10 31
Thompson Run 55 35 10 88 43 17 4 26 63 2 5

Thompson Run averaged 4.8 m (16 ft) wide and 0.3 m (1 ft) deep. Riffles made up 55% of the instream habitat (Table 8) and 88% of the bank were rated as stable. Gravel was the predominant substrate and cobble ranked second.

In June 1997, the discharge of Slab Cabin Run leaving the marsh was 21.48 cfs and about 40% of this flow was from upper Slab Cabin Run (Fig. 3). Most of the flow in Thompson Run originates from Thompson Spring, which contributed about 48% of the flow leaving the marsh. The remainder of flow came from Bathgate Spring (7%) and 1 cfs originated from smaller springs that we did not attempt to measure.

Pict0029.TIF (2844874 bytes)
Fig 3:  Stream discharge data (cfs) for 3 stations in Millbrook Marsh

In October 1997, following a dry summer, the discharge of Slab Cabin Run leaving the marsh was 9.67 cfs and only 13% of this water was contributed by upper Slab Cabin Run. Thompson Run contributed 66% of the flow and the remainder was provided by Bathgate Spring and other unmeasured springs. These data illustrate the importance of ground water in maintaining the aquatic communities in the marsh.

On to Soils