RECREATION TRAILS AND WATER QUALITY: ARE RECREATION TRAILS DEGRADING STREAM QUALITY?

The U.S. Forest Service identified public recreation as one of the four greatest threats to forested landscapes. To quantify the ecological impact of recreation trails we sampled 112 trail segments (55 motorized, 26 non-motorized, 31 non-mechanized) in Maine and New Hampshire. Where recreation trails crossed stream channels we recorded the crossing structure (culvert, bridge, or ford) and assessed sediment inputs and habitat connectivity. Sediment inputs were classified as none, trace (visible, but minor), measurable (forms sediment fan), and catastrophic (significantly alters stream morphology). We found that 38% of stream crossings had no sediment inputs, 29% of crossing had trace sediment inputs, and 24% had measureable inputs. The 9% of stream crossings with sediment additions classified as catastrophic included trails of all use types- non-mechanized (2%), non-motorized (2%), and motorized (5%). The majority of trails (7%) with catastrophic sediment additions were on streams 1-2m in width. Stream crossing structures (bridges and culverts) can cause interruptions in natural stream substrate, abrupt changes in stream elevation, or significant reductions of water depth or flow that would interrupt or impede movement of aquatic organisms. On the recreation trails we sampled 26% of stream crossings were classified as restricting habitat connectivity. Of the crossings with connectivity issues the majority (24%) occurred on streams less than 5m wide. The results of this study have direct implications for trail managers and land owners. All trail types (motorized, non-motorized, and non-mechanized) were found to contribute sediment to streams and degrade stream quality. Small streams were found to be particularly vulnerable to sediment inputs and migration blockages. These streams may be simply overlooked by managers and/or financial resources may be directed to infrastructure on larger streams. However, they are a critical part of aquatic ecosystems and must be managed appropriately.