As stormwater flows over driveways, lawns, and sidewalks, it picks up debris, chemicals, dirt and other pollutants. Stormwater can flow into a storm sewer system or directly to a lake, stream, river, wetland, or coastal water. Anything that enters a storm sewer system is discharged untreated into the water we use for swimming, fishing, and providing drinking water. Polluted runoff is the nation’s greatest threat to clean water.
Since the passage of the Federal Water Pollution Control Act, the quality of our Nation's waters has improved dramatically. Despite this progress, however, degraded water bodies still exist. According to the 1996 National Water Quality Inventory, approximately 40 percent of surveyed U.S. water reserves are still impaired by pollution and do not meet water quality standards. A leading source of this impairment is polluted storm water runoff. In fact, according to the Inventory, 13 percent of impaired rivers, 21 percent of impaired lake acres, and 45 percent of impaired estuaries are affected by urban/suburban storm water runoff. Six percent of impaired rivers, 11 percent of impaired lake acres, and 11 percent of impaired estuaries are affected by construction site discharges.
The City of Calistoga recognizes that contaminants and impurities in stormwater runoff are a major threat to the quality of our environment and our water supply and is taking steps to mitigate the problem.
Construction Site Runoff Control and Post-Construction Runoff Control Measures
There are two State NPDES permits that regulate polluted runoff from construction sites: NPDES Construction General Permit and NPDES Municipal General Permit. Calistoga has adopted the BASMAA Post-Construction Manual for Design Guidance for Stormwater Treatment and Control for Projects.
NPDES Construction General Permit
Significant new requirements! See this Presentation on the Construction General Permit for more information.
Any property owner whose project disturbs one acre or more of soil is required to obtain coverage under the General Permit for Discharges of Storm Water Associated with Construction Activity. Construction activity subject to this permit includes clearing, grading and disturbances to the ground such as stockpiling or excavation but does not include regular maintenance activities performed to restore the original line, grade or capacity of the facility.
You can learn more about the State Construction General Permit at the
State Water Resources Control Board's web site.
NPDES Municipal General Permit
All of the incorporated and unincorporated areas within the Napa River watershed are covered under the Phase II NPDES Municipal General Permit. Under this permit, the City is required to develop, implement and enforce a program to reduce storm water runoff pollutants. This program includes the following:
• legal authority to establish BMP requirements
• procedures for site plan review
• procedures for receiving complaints from the public
• procedures for inspection and enforcement