Construction Site Runoff

Construction site runoff is one of the greatest contributors of sediment and pollutants to tributaries and washes. Sediment yields from construction sites are from 20 to 2000 times greater than that from agriculture or forest lands, respectively.

Metals in Runoff

A significant concentration of metals is absorbed on the surfaces of the sediment particles, because the soil surfaces are negatively charged and the metals are predominantly positively charged. Once in the stream system, if something occurs that causes the pH to become acidic, the metals on the sediment may be dissolved into the streamflow. In addition to sediment, construction site runoff can contribute solid and sanitary waste, nutrients, pesticides, lubricants, chemicals and trash and debris to washes.


Construction site runoff and pollution control is one of the 3 program elements that require enforcement on the part of Coconino County. All construction sites disturbing one acre or more of land are subject to the stormwater construction site runoff control requirements.

The County uses a Stormwater Ordinance, and standards within the existing Building, Health, and Grading ordinances to help control construction site runoff and pollution. The County will also be adopting a stormwater ordinance for this purpose. To this end, SWPPPs with erosion and sediment control plans must be reviewed and approved by the county prior to any site disturbance. The ordinance includes:
  • Requirements for erosion and sediment control and control of other wastes.
  • Pre-construction site plan reviews to address potential stormwater impacts.
  • Procedures for site inspections during construction and the enforcement approach.
  • Other enforcement measures where willful violations are occurring.

Public Participation

The County continues to provide construction site runoff control information to the public via brochures & presentations at neighborhood watch meetings, community picnics, and county safety days. Public participation in reporting possible construction site runoff water quality violations is encouraged.