East Branch Pecatonica River
Restoration of watersheds and streams in the Driftless Area was essentially started back in the 1930s with the implementation of soil conservation practices. Since the 1950s, in-stream habitat improvement using hard structures (usually in combination with fish stocking) in order to restore trout populations has occurred on many Driftless Area streams with good success (Hunt 1988, Avery 2004). However, recent research has suggested that successful restorations need to be process-based as well as conducted at the watershed scale in order to achieve long-term sustainability of ecosystem services (Wohl et al. 2005). The headwaters of the East Branch Pecatonica River has recently become the location of a rare example of this type of watershed-scale restoration of the processes that once created and sustained diverse and productive streams and floodplain wetlands.
Beginning with a donation of land to The Nature Conservancy (TNC) in 1964, the Military Ridge Prairie Heritage Area (MRPHA) has become one of the highest concentrations of grasslands in the Midwest (for more information - click here). Owned and managed by a consortium of non-profit groups and private landowners, the 50,000+ acres of the MRPHA provide critical habitat for rare bird and plant species. In addition, these grasslands with their high infiltration capacities and low erodibility potential create the conditions necessary for effective stream and floodplain restoration downstream.
© Gerald H. Emmerich, Jr.
STREAM / FLOODPLAIN
Led by TNC and the Wisconsin Department of Natural Resources (WDNR), a novel restoration technique is now being pioneered at a site owned by TNC along the headwaters of the East Branch Pecatonica River with 800 meters of stream length (500-meter valley length). This technique is based on removal of the accumulated, “cultural,” floodplain sediment to restore the pre-settlement soil surface and improve the connections between the channel and the floodplain. Lowering of the ground surface decreases the depth to the water table, which may lead to establishment of plant types that are found in wetter environments. In addition, woody debris that has encroached into the channel and riparian area is removed to increase stream velocities and substrate grain size and decrease stream width.
In the summer of 2006, the encroached box elder community along the riparian zone was removed along with approximately 70 cm of sediment on the west floodplain (which was previously cropland). Banks were only sloped on the east side due to conservation lands and valley constraints. The sediment removed from the site was donated to the county highway department and several private landowners who were willing to haul it away. Immediately following sediment removal, a cover crop was planted to minimize sheet erosion from the site and a diverse seed mix of native mesic and wet prairie species was planted.
This technique appears to be a promising way of re-introducing floodplain and in-stream habitat that have been substantially diminished in the Driftless Area. However, like many other restoration techniques, a detailed assessment of this technique and its associated impacts on stream/floodplain hydrology, floodplain vegetation, and stream temperature has never been performed.
COIR LOG INSTALLATION
In June of 2007, 420 feet of coconut fiber (coir) logs was installed to narrow the stream channel in lower gradient reaches and to protect against streambank erosion. Aided by floods in August, fine sediment quickly deposited between the coir logs and the bank where Glyceria has now colonized. Slack water created by the structures leaves ideal habitat for amphibians and early life stage fish.