Vol. 26, No. 6 ● August 23, 2018
Approved Accotink Creek "Salt" TMDL -
What it Means to You!
On May 23, 2018, EPA approved sediment and chloride Total Maximum Daily Loads (TMDLs) for Accotink Creek to address aquatic life use impairments resulting from sediment and chloride (i.e., the use of “road salt”):
- EPA-approved Accotink Creek Sediment TMDL Report
- EPA-approved Accotink Creek Chloride TMDL Report
- EPA Approval Letter and Decision Rationale
The TMDL quantifies the maximum amount of the total pollutant that the water body can receive without exceeding water quality standards. Note that the previous attempt to enact a sediment TMDL for Accotink Creek in 2013 failed as it attempted to mandate flow rate reductions (as increased stormwater runoff leading to bed and bank erosion was deemed to be a primary reason for the excessive sediment). Because stormwater runoff is not a “pollutant,” the TMDL was not approved.
Average annual loads have been developed for the three primary stream reaches – Upper Accotink (from headwaters down to Lake Accotink), Lower Accotink (from Lake Accotink to the Potomac River), and Long Branch. The total TMDL for each of the three reaches (expressed in tons/yr for sediment and lbs/yr for chloride) is comprised of load limits for 3 separate sectors:
- Waste Load Allocations (WLAs) from permitted, point discharges (includes MS4’s, process water discharges, industrial discharges, construction site runoff, and future growth),
- Load Allocations (LAs) from nonpoint sources (primarily areas outside of MS4 boundaries, the drainage areas to industrial stormwater outfalls, or from background levels), and
- Margin of Safety (MOS) that is defined as 10% of the total TMDL to account for uncertainty in the relationship between pollutant loads and water quality.
Contributing sources of sediment included in the model used to develop the TMDL are construction, transportation, streambank erosion, open space, and other developed areas. Of these, streambank erosion represents the single greatest source at approximately 85% of the total load. To meet the TMDL loading, an overall sediment reduction of approximately 72% will be required over time. Chloride levels are attributed to the application of deicing salts.
It is recognized that achieving the goals of the sediment TMDL will be a long term, iterative process, with the initial emphasis on those control actions that have the largest impact on water quality. DEQ intends to use existing state programs to meet the objectives of the TMDL:
WLAs: Load reductions from WLAs will be addressed either through the effluent limits in existing discharge permits, or through development of a specific TMDL Implementation Plan.
LAs: It is recognized that the current Virginia Stormwater Management Program (VSMP) regulations will, over time, result in sediment load reductions. However, since discharges are not specifically regulated by an existing permit (as is the case with the WLAs), a TMDL Implementation Plan will be required to comply with state law. The Implementation Plans “shall include the date of expected achievement of water quality objectives, measurable goals, corrective actions necessary and the associated costs, benefits, and environmental impacts of addressing the impairments”. It is anticipated the types of BMPs that will be used include stream restoration, stream bank stabilization, and BMPs that reduce stormwater runoff. Stakeholders will have the opportunity to participate in development of Implementation Plans. Stay tuned for more information on this process!
With public safety of critical importance, it is anticipated that achieving the chloride load reductions will be through performance-based BMP’s that will focus on training and technological improvements in the application of deicing salt. Rather than developing a traditional TMDL Implementation Plan, the chloride TMDL will be addressed through development of an Accotink Creek Salt Management Strategy (SaMS). The Stakeholder Advisory Committee (SAC) was formed at the beginning of the year and the selection of the Workgroup is underway, with the first meeting anticipated to take place in the August/September timeframe. More information on the SaMS can be found here.
For more information about the Accotink Creek TMDLs, please contact Frank Graziano in our Gainesville office.