Pima County Department of Environmental Quality monitors ambient (outdoor) air pollutants throughout eastern Pima County, including the Tucson metropolitan area and Green Valley. There are six principal pollutants, called “criteria” pollutants that are monitored in accordance with the National Ambient Air Quality Standards set by the Environmental Protection Agency to comply with the Federal Clean Air Act. These standards were established to protect public health and the environment from harmful levels of air pollution.

The Pima County Department of Environmental Quality has prepared this document to be submitted to the U.S. Environmental Protection Agency, Region IX. The purpose of the Ambient Air Monitoring Network Plan is to determine if the network is achieving the air monitoring objectives specified in 40 CFR Part 58 Appendix D, which mandate adherence to certain number, type and location requirements of monitoring sites and specific site criteria such as monitoring inlet height. The review should also determine if modifications should be made to the network (e.g. through the termination or relocation of unnecessary stations or addition of new stations). In addition, the review is necessary in order to ensure that the residents of Pima County are provided adequate, representative and useful air quality data, and to provide adequate protection to public health.

This Technical Data notebook has been prepared for a Letter of Map Revision application for a portion of the Via Entrada Wash located in Pima County, Arizona. The objective of the TDN and LOMR submission is provide regulatory discharge rates and floodplain limits along the Via Entrada Wash using better topographic, hydrologic, and hydraulic data.