This Stormwater Assessment and Education Report was completed by Matrix Design Group for the City of Glenwood Springs through a grant from the U.S. Environmental Protection Agency, administered by the Water Quality Control Division (WQCD), and sponsored by the Roaring Fork Conservancy. The following project partners also contributed to the completion of this report: the City of Glenwood Springs, the Colorado River Water Conservation District, and Glenwood Springs High School. The objective of this report is to:
- Evaluate non-point source pollution to waterways, and
- Develop an education project on the stormwater impacts to water quality in the Glenwood Springs area.
Value of this Study
This project provided the following new tools to the City for management of stormwater runoff:
- GIS Database of Stormwater Infrastructure, including pipe sizes, type and location. (Prior to this study, the City had limited information on manholes and inlets, but no comprehensive database of public and private storm drains.)
- Electronic Mapping of Drainage Basins, within the City boundaries and contributing off-site basins from the surrounding hillsides. A fold-out map of the entire City and contributing hillsides is included at the end of this report, along with six 11x17 color maps of the City showing basin boundaries, existing infrastructure and recommended stormwater controls. (Prior information was available in hard-copy only of basins originally delineated for mud flows by ESA Geotechnical Consultants and ARIX in a 1982 Drainage and Debris Control Plan. The U.S. Army Corps of Engineers restudied the drainage basins in a 1997 Flood Insurance Study of hillside debris flow. This report began with the previously delineated basins and carried the basins through the City and specifically examined stormwater basins inside the City of Glenwood Springs.)
- Identification and Inventory Major Storm Drain Outfalls. Using the database of storm pipes and topography, stormwater outfalls were identified and classified according to their drainage basins and contributing land use areas. These outfalls were correlated with the watershed boundaries.
- Field Confirmation of Stormwater Outfalls. Matrix personnel toured the City with the assistance of City Staff to map storm drains and previous efforts for stormwater controls and water quality management. Manholes were opened and pipes were measured to develop an accurate database of stormwater controls. A photo inventory of stormwater controls is included in this report, along with the citywide mapping.
- Recommendations for Stormwater Improvements. Once the City stormwater system was mapped and analyzed, recommendations were made for stormwater infrastructure, management and ordinances. This report provides a comprehensive summary of stormwater regulations, management techniques and a listing of controls to improve the quality of stormwater runoff.
- Educational Materials on Non-Point Source Pollution have been provided to educate the community on the impacts of urban runoff and to implement controls to halt the degradation of the Roaring Fork and Colorado River’s water quality throughout the City.
This report is a first step toward meeting upcoming drainage regulations, and more importantly, protecting the Roaring Fork and Colorado River watersheds that are so highly valued by the Glenwood Springs community. Although this report provides many recommendations to the City and comprehensive mapping of the storm drainage infrastructure, more detailed drainage master plans should be developed to identify capital improvement projects that will reduce the City’s susceptibility to periodic flooding, debris flow damage, ice build-up, and to comprehensively improve the quality of stormwater runoff.
Drainage is frequently ignored but can have a major impact on the Glenwood Springs community. The City is highly susceptible to damage from stormwater runoff resulting in mud and debris flows as witnessed on a large scale in 1977 and 1981. The solution at the time was to figure a way to convey this mud into the rivers. New trends in Clean Water Act regulation are focused on degradation of stream water quality as the result of sedimentation and urban runoff. Glenwood Springs, located at the confluence of the Roaring Fork and Colorado Rivers, takes great pride and character from its proximity to the pristine waters through the heart of town. The Gold Medal waters of the Roaring Fork River, along with the Colorado River, are irreplaceable amenities that can be damaged by pollutants carried to the stream system by stormwater runoff. A paradigm shift has occurred within the stormwater management community to change from a philosophy of sending everything into the rivers for dilution, to a vision of protection of rivers and streams by holding back pollutants in the runoff.
Glenwood Springs is a mountain community without extensive stormwater infrastructure or federally mandated stormwater programs. Nonetheless, the City is experiencing the effects from urban stormwater runoff, particularly given exploding trends in population growth and land development. The effect of non-point source pollution on the river water quality is often significant, given the dramatic changes occurring across the urban landscape. The City of Glenwood Springs requires stormwater management practices for certain activities. However, it does not have a comprehensive stormwater plan, resulting in an unspecified pollutant load entering both the groundwater table and river. Understanding the impact of stormwater runoff on water quality and developing a recommended plan for managing such runoff is crucial to protecting the health of the rivers.
There is an opportunity to improve the management of stormwater runoff in Glenwood Springs. The federally mandated National Pollutant Discharge Elimination System (NPDES) stormwater regulations under the Clean Water Act do not yet require Glenwood Springs to participate in the permit program, but plans indicate the Glenwood Springs will likely be required to address stormwater quality sometime within the next five years. Although Glenwood Springs is not a “Phase II Community,” this report has been designed and formatted to prepare the City for eventual inclusion in the Clean Water Act NPDES program. The report is sub-divided into six categories that have been established by the Federal Government and are the basis for improving stormwater runoff water quality:
- Public Education and Outreach on Stormwater Impacts.
- Public Involvement/Participation.
- Illicit Discharge Detection and Elimination.
- Construction Site Program.
- Post-Construction Stormwater Management.
- Pollution Prevention/Good Housekeeping for Municipal Operations.
The next step after this study will be to design and implement stormwater controls, and to assess the effectiveness of improved stormwater management and “Best Management Practices” (BMP’s). Such improvements may include development of more and better detention and treatment facilities, use of wetland and riparian buffer systems, establishment of a stormwater quality control program, and the incorporation of new stormwater drainage ordinances. The following steps should be undertaken to improve the quality of stormwater discharges and prevent periodic flooding and damage caused by stormwater runoff:
- Develop a Drainage Infrastructure Master Plan that specifically identifies deficiencies in the drainage system and proposes new infrastructure.
- Prioritize the infrastructure capital improvements.
- Develop Budget and Funding mechanisms to implement the Drainage Infrastructure Master Planned improvements. To fund storm drainage capital improvements and necessary drainage maintenance, a newer approach that is finding favor in many cities is the creation of a Stormwater Drainage Utility, which bills the “users” (residents) of storm sewer drainage improvements an appropriate amount each month or quarter, similar to billing for sanitary sewer.
- Educate the Community on the implications of urban stormwater runoff and better stormwater management techniques.
Opportunities in Glenwood Springs for better Stormwater Management include:
- Emphasize Stormwater Management in Ordinances
- Improve Drainage Conveyance (Pipes & Culverts) to reduce flooding
- Stormwater Detention/Retention Ponds to prevent injury to downstream properties caused by upstream development
- Sedimentation Ponds to capture mud and debris flow
- Water Quality Treatment Ponds to improve the quality of stormwater runoff
- Better Erosion Control practices during construction to improve water quality Page