The City of Merced is a regulated Small Municipal Separate Storm Sewer System (MS4). This means that the sewer system and storm drain system are separate. Wastewater that enters into the sewer system is directed to the local City of Merced Wastewater Treatment Facility (WWTF), treated, then released back into the environment. Stormwater is precipitation runoff that is directed to the MS4, not treated, and directly discharges to local creeks, such as, Bear Creek, Black Rascal Creek and Cottonwood Creek.
In 1990, the Environmental Protection Agency (EPA) established the Phase I National Pollutant Discharge Elimination System (NPDES) Stormwater Program, the City of Merced falls under the Phase II portion of this program. Operators of regulated Small MS4's are required to design their programs to:
The Construction MEP's for Small MS4 Construction Stormwater are:
Uncontrolled runoff from construction sites is a water quality concern because of the devastating effects that sedimentation can have on local waterbodies, particularly small streams. Numerous studies have shown that the amount of sediment transported by stormwater runoff from construction sites with no controls is significantly greater than from sites with controls. In addition to sediment, construction activities yield pollutants such as pesticides, petroleum products, construction chemicals, solvents, asphalts, and acids that can contaminate stormwater runoff. During storms, construction sites may be the source of sediment-laden runoff, which can overwhelm a small stream channel’s capacity, resulting in streambed scour, streambank erosion, and destruction of near-stream vegetative cover. Where left uncontrolled, sediment-laden runoff has been shown to result in the loss of in-stream habitats for fish and other aquatic species, an increased difficulty in filtering drinking water, the loss of drinking water reservoir storage capacity, and negative impacts on the navigational capacity of waterways.
To view National Pollutant Discharge Elimination System (NPDES) - Stormwater Phase II Final Rule Fact Sheets click on the link below:
WGR Southwest, Inc. issues a monthly stormwater newsletter called "Monthly Dirt" for information to assist in compliance with California's Construction General Permit. Click on the link below to view the newsletters"