Source Control Strategies - Chehalis River Council Development, Storm Water and Erosion Source Control Strategies Urbanization frequently results in clearing of vegetated areas. When soil erosion occurs during clearing, site preparation, and construction operations, valuable fish spawning areas can be covered with silt. Removal of vegetation, erosion and siltation can degrade habitats of birds, invertebrates, and plants. Studies from other states indicate that urban runoff from storms may be as bad or worse than the effluent from primary sewage treatment plants.
Storm water runs directly into surface waters without treatment.
The magnitude and frequency of flooding may increase as vegetation cover and permeable soils are replaced by impermeable surfaces. Erosion and streambed scouring results in habitat loss for fish and invertebrate species. Increased overland flows due to lack of infiltration, lower permeability, or impermeability can reduce ground water recharge, presenting serious problems when a ground water aquifer is used as a source for a public water supply, e.g. the Centralia area aquifer. Construction practices, increased impervious surfaces, clearing and grading, filling of wetlands, and the increased use of lawn care products such as fertilizers and pesticides all contribute to nonpoint source pollution in developing areas of the basin. Contractors must be educated in the control of erosion during construction.