"Chop and drop" a success in the Sunday River and Bear River headwaters
"Treated" site in the Sunday River headwaters
ARWC’s “chop and drop” project successfully concluded in 2010. This multi-year project was funded by the Eastern Brook Trout Joint Venture. It studied the effects of adding coarse woody material (trees) to streams in the headwaters of the Sunday and Bear Rivers. Adding woody material to streams in this manner is thought to mimic historic conditions before land clearing and modern land use practices such as agriculture, road building, and timber harvesting created the tree-free streams we see today. Trees are cut at strategic intervals along a stream to fall into the water. Depending on gradient, water velocity and other conditions in a particular location, the addition of woody material may cause scouring to create the deep pools favored by brook trout or form “dams” to trap sediment that is eroding from nearby roads.
Treatment took place in 2007 and data was collected annually in the summers of '08, '09 and '10. Monitoring included surveying cross-sections and longitudinal profiles to assess geomorphic changes to the streams after treatment, pebble counts, biological monitoring of brook trout and aquatic insects, and measuring water levels above and below treated areas to assess whether “chop and drop” dampens the high degree of flashiness exhibited by these streams after spring runoff and summer storms.
ARWC worked with the University of Maine, U.S. Fish & Wildlife Service, Maine Department of Inland Fisheries & Wildlife, Town of Newry, and private landowners on this project. While the “official” EBTJV grant ended in 2010, the University of Maine, with ARWC assistance, applied successfully to another fund to continue biological monitoring in 2011, and ARWC and the surveyor re-deployed the water level loggers in May, 2011 for another season of data collection. The loggers will be retrieved and analyzed in late October or early November, 2011.
The data through 2010 show multiple benefits from “chop and drop”, such as creation and enhancement of brook trout habitat, moderating stream flashiness to create more stable flows, an increase in production of the aquatic insects upon which brook trout prey, and improvements in erosion control. Trend analysis shows brook trout populations in treated streams have rebounded, and in some cases exceeded, levels found before treatment caused a short-term disruption in habitat; now that the “chop and drop” has largely stabilized this upward trend is expected to continue.
ARWC and fisheries agencies are excited about the results of the ARWC study. “Chop and drop” shows promise for addressing a host of problems, at relatively low cost, in remote New England headwater streams.