Why the Harpeth River is not Meeting Water Quality Standards in the summer:
Do you enjoy swimming, paddling, tubing, fishing, and playing on the Harpeth River? No matter where your favorite spot is along the main Harpeth, most of it does NOT meet water quality standards during the summer. According to TDEC, starting downstream of College Grove the river for 21 miles is impaired as it flows through WIlliamson County and all the way through downtown Franklin to the City's sewage treatment plant behind Franklin High School. From there, for another almost 50 river miles the Harpeth RIver is also below water quality standards as it flows through Davidson County (which is the State Scenic River section) and through parts of the Harpeth River State Park in Cheatham County until the confluence with the South Harpeth near Kingston Springs. TDEC counted close to 300,000 people who visited just the highly popular Harpeth River State Park in 2010.
In 2010, for the first time, the 3 state sewage treatment plant permits that serve all the growth in Franklin and northern Williamson County were revised simultaneously as a step toward reducing pollutant load into the river. While some aspects of the proposed permits are tighter, they still allow twice as much pollutant load than the river can handle in order to meet state water quality standards based on analysis done by the EPA.
IN 2012, the city of Franklin consultant's presented a proposal for a long-term sewer and water plan. It not only did not improve the water quality in the Harpeth, but was proposing a new sewer plant just upstream of the city's drinking water plant. The "Toilet to TAP" would have the city's drinking water customers be the first in the country to do this. The City aldermen did not support this proposal, but worked from this significant study to choose some logical steps forward.
BACKGROUND: The Harpeth River in the summer is “effluent dominated."
For over a decade, studies by the EPA, TDEC, HRWA and others, have recorded oxygen levels in the river water well below state standards. Dissolved oxygen levels in the river water have been recorded at less than half the state standard of 5 mg/l and even lower, at levels that stress fish which have trouble breathing and feeding and will not reproduce. See two charts below that show TDEC data and HRWA results from our 2006 Dissolved Oxygen study. (This report includes all D.O. data from TDEC and EPA up to this year. More recent studies from 2007 and 2008 are in a separate report.) Pollutants from sewer plant discharges, septic seepage, and urban and agricultural runoff feed the growth of algae and bacteria that cause the water’s oxygen levels to drop very low and give the river a green color when in healthier conditions it would be clear.
The largest pollutant sources are the sewer plants that serve Franklin and Northern Williamson County that discharge into the Harpeth in one 17 mile stretch (Franklin, Lynwood that serves Cottonwood, and Cartwright Creek that serves River Rest). The largest sewer plant in the entire river system is the city of Franklin’s with a design capacity of 12 million gallons per day (12MGD).
In comparison, the flow in the Harpeth in downtown Franklin can be as little as only 1/2 million gallons per day. This is the extreme low flow condition for the Harpeth that the sewer permits are supposed to be designed to protect. The other two sewer plants are much smaller (each around ½ million gallons a day), but still large enough to affect the river’s water quality as seen in the river dissolved oxygen studies and discussed in a water quality analysis funded by HRWA.
HRWA, SELC, city of Franklin, and TDEC have met with the U.S. Environmental Protection Agency and USGS to begin planning for a new study of the Harpeth River, particularly now that conditions have changed with the removal of the low-head dam. The study, called a Total Maximum Daily Load (TMDL), is a calculation of the maximum amount of a pollutant a waterbody can receive and still meet water quality standards, and an allocation of that load among the various sources of that pollutant. TDEC will lead the new TMDL, with support from EPA and including significant stakeholder input, to look at the entire Harpeth River Watershed.
HRWA's GOAL FOR THE HARPETH RIVER: Meet Water Quality Standards and Maintain Natural River Flows
Draft and final permits and further information is available by contacting Gary Davis, Gary.Davis@tn.gov , (615) 532-0649, at TN Department of Environment and Conservation.
Comments submitted by the HRWA and Dissolved Oxygen Studies are all accessible in the Library of this web site. HRWA comments to TDEC on the revised permits: December 2009, and additional comments for the public hearing in August 2010.
Not all of the attachments to HRWA's comments nor comments submitted by other entities are on this web site. If you would like these documents, please contact, Dorene Bolze, Executive Director.