Positive actions are being undertaken and accomplished to improve water quality in the Chetco, Coos, Coquille and Sixes rivers and area tributaries. We appreciate your interest and involvement. Together we can work towards a better river environment for everyone.
Coquille Subbasin Tools
|The Oregon Coquille River Watershed Total Maximum Daily Load Mapping Tool
is designed to help those working to improve vegetated buffers or riparian areas along the Coquille River. The tool allows users to identify high-priority riparian sites and helps ensure enhancements are made in areas where they will improve water quality. The tool shows users the amount of light and heat the sun delivers under existing riparian conditions and how much light and heat an improved riparian area could block. Many manmade and natural factors influence stream temperature. Reducing shade by removing riparian vegetation is just one activity that can contribute to stream warming. Elevated stream temperatures have been shown to limit aquatic life and salmonid and trout rearing and migration.
This tool also provides fish distribution information for multiple fish species and those using the tool can find areas where the potential to improve both water quality and fish habitat is high. Coquille River coho salmon are identified as threatened under the Endangered Species Act. The recovery plan for these fish emphasizes the importance of healthy riparian areas because they provide shade and maintain cool water temperatures for fish. Although riparian plantings take a long time to mature, this tool allows users to preview the potential for improving stream shade over time and provides a unique opportunity to track progress toward improving water quality in the Coquille River.
Supporting Assessment Reports
The Coquille TMDL Low Impact Development Implementation Tool was developed to assist in the implementation of both the Coquille TMDL and Coastal Nonpoint Management Area post construction runoff requirements. The tool provides design storm sizing for LID Best Management Practices (BMPs) specific to the four Western Oregon coastal communities located within the Coquille Watershed: Bandon, Coquille, Myrtle Point, and Powers. The Tool builds upon the Low Impact Development in the Western Oregon Low Impact Development
template and incorporates an approach similar to the City of Eugene’s Simplified Approach for Stormwater Management (SIM). The modified SIMs calculator considers coastal hydrological patterns (design storm sizing), soils permeability, and BMP runoff reduction values to produce a coastal specific stormwater output for selected BMP design sizing. The tool provides stakeholders with an implementation-ready tool to plan, develop, design, and implement LID projects within their jurisdictions.
The tool incorporates two different design storms: 24-hour design storm to protect water quality on-site and downstream based on the 95th percentile storm and the NOAA ESA west coast region design storm (facilities designed to accept and fully treat 50% of cumulative rainfall from a 2-year, 24-hour storm). DEQ has provided design storm analysis for up to three urban areas: one each for Bandon and Powers and a separate for the combined area of Coquille and Myrtle Point. The tool also incorporates a range of Coquille watershed soil permeability rates and provides a permeability rate drop down box for developers to match their site to soil type. However, due to the variability of soil survey information, onsite soil infiltration testing is recommended for all engineered BMPs. This Tool supports implementation of the Coquille Sub-basin TMDL and Coastal Nonpoint Management Area stormwater runoff requirements by allowing community planners and developers to design and implement size appropriate BMPs to manage the runoff from storms that have a potential to impact water quality within the Coquille watershed.
LID Tool Supporting Documents