A Natural Resource Management Guide for the County of Morris A ...

Human Derived Impacts
Natural hazards associated with surface water including flooding, erosion, and sedimentation are
exacerbated by human activities and usually relegated to the realm of stormwater management. While
impact is separated out into water quality and water quantity, the two are joined from a resource
management perspective. Changes in volume, velocity, and composition of stormwater runoff have
tremendous impact on ecosystems. A generalized depiction of impacts is outlined below.
Changes to Stream Hydrology
+ increase in magnitude and frequency of severe floods
+ increased frequency of erosive bankfull floods
+ increase in annual volume of surface runoff
+ more rapid stream velocities
+ decrease in dry-weather baseflow in stream
Changes to Stream Geomorphology
+ stream channel widening and downcutting
+ increased streambank erosion
+ shifting bars of coarse grained sediments
+ elimination of pool/riffle structure
+ imbedding of stream sediments 5
+ stream relocation/enclosure or channelization
+ stream crossings form fish barriers
* Lesser Bladderwort
Changes to Water Quality
+ massive pulse of sediment during construction stage
+ increased washoff of pollutants
+ nutrient enrichment leading to benthic algal growth
+ bacterial contamination
+ increase in organic carbon loads
+ higher levels of toxics, trace metals & hydrocarbons (Pb, Cd, Cu, & Zn)
+ water temperature enhancement
+ trash/debris jams
Changes to Aquatic Ecology
+ reduction in diversity of aquatic insects
+ reduction in diversity and abundance of fish
+ destruction of wetlands, riparian buffers, and springs
* Small Yellow Pond Lily
5
Imbedding occurs when sand, silt and clay fill up the interstitial voids between larger cobbles and gravels.
This sharply limits the quality and availability of fish spawning areas, particularly for trout. (Schueler, 1991)
A Natural Resource Management Guide
for the County of Morris 107