NPDES Permitting


Municipal Stormwater Permit
Implementation Activities

John T. Doerfer
Project Hydrologist, Master Planning Program

The District continued to assist the cities of Denver, Aurora, and Lakewood in 1997 with planning activities related to implementation of their stormwater permits. A permit authorizes the holder to discharge runoff from its storm sewer system in accordance with approved stormwater management programs. The three cities proposed management programs in their permit applications submitted in November 1992. Permits were issued by the State of Colorado in May, 1996. The Clean Water Act requires that all permit requirements be implemented within three years of permit issuance. The permits define an implementation schedule that the three cities must meet for full compliance by June 10, 1999.

Some elements of the permits--such as street sweeping, inlet cleaning, and trash/debris removal from channels--existed prior to any permits. These are no longer discretionary activities and must be continued by the cities. The new programs required by permits and developed in 1997 by the three cities, with District assistance, include:

Annual Reporting and Cost Estimates

There are a variety of specific data to be reported each year.  Early in 1997, the cities, with assistance from the District, developed databases, cost-estimating worksheets, and report templates to be used for each city’s annual report.

Industrial Facilities Program

Although specific industrial sites must obtain an individual stormwater permit from the State, the three cities were required to implement a program to inspect and monitor certain industrial sites within their jurisdictional area as well. This program was approved by the State after extensive review and discussion in 1997.

Municipal Facility Runoff Controls

The cities operate certain facilities similar to those in the private sector--such as vehicle-maintenance yards--that require industrial stormwater permits. The Best Management Practices (BMPs) for use at these sites, and the list of sites and schedule for plan implementation before 1999, were approved this year.

Wet-Weather Monitoring Program

The permits also require the cities to develop a wet-weather monitoring plan that meets the State’s and DRCOG’s Total Maximum Daily Load (TMDL) study and planning needs. The District entered into agreements with the three cities and Arapahoe County to assist them with wet weather monitoring. The monitoring plan prepared by the District was approved by the TMDL Advisory Committee and State of Colorado in April. The U.S. Geological Survey has worked with the District to install monitoring equipment at five sites. Wet-weather monitoring will begin in the spring of 1998.

Dry-Weather Sampling Protocols

The cities sampled all of their major storm-sewer outfalls during dry weather as a requirement of permit applications. Permits require that these same outfalls, and additional ones, be sampled again once during the 5-year permit term. The District assisted cities in 1997 develop improved sampling protocols.

Other major programs currently in development include public education, new development planning procedures, and construction-site sediment control.


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