Volume 26, Number 6    August 9, 2018

Approved Accotink Creek "Salt" TMDL -
What it Means to You!

NOT READY TO SEND - check BOLD Accotink text with Frank, adjust in Index page, article page (top and bottom), and Constant Contact.


On May 23, 2018, the EPA approved sediment and chloride Total Maximum Daily Loads (TMDLs) for each of three impaired segments of Accotink Creek – Upper Accotink (from headwaters down to Lake Accotink), Lower Accotink (from Lake Accotink to the Potomac River), and Long Branch.  Accotink Creek drains 52 square miles of Fairfax County in Northern Virginia, and these TMDLs quantify the maximum amount of total pollutant that the water body can receive without exceeding water quality standards.  All development projects within the Accotink Creek watershed are subject to these TMDLs, and the Virginia Department of Environmental Quality (DEQ) must consider how proposed impacts to the watershed affect sediment and chloride levels when issuing stormwater permits.[SB1] 

 [SB1]I added this – is this true?  If not, what is the actual impact on clients?  What will they have to do differently now that these TMDLs are in place?  How will DEQ look at projects within this area differently?

Why are TMDLs Necessary?

Section 303(d) of the Clean Water Act (CWA) and the United States Environmental Protection Agency’s (EPA) Water Quality Planning and Management Regulations (40 CFR part 130) instruct states to develop TMDLs for waterbodies that are not meeting water quality standards.  Since DEQ’s benthic monitoring and assessments show that Accotink Creek is not supporting Aquatic Life Use, the agency added these three impaired segments to Virginia’s List of Impaired Waters and developed TMDLs to address this impairment – which is believed to be largely the result of sediment and chloride deposits from the use of “road salt” during winter months. 

You can read the complete TMDL reports on DEQ’s website:

Note that a previous attempt to enact a sediment TMDL for Accotink Creek in 2013 failed because it attempted to mandate flow reductions. TMDLs must only address pollutants, and those proposed in 2013 focused on the excessive sediment from bed and bank erosion due to increased stormwater runoff – and were therefore not approved, because stormwater runoff is not a pollutant.


Average Annual Load Allocations for Accotink Creek Primary Stream Reaches

DEQ has developed average annual loads for the three primary stream reaches.  The total TMDL for each reach is expressed in tons/yr for sediment and lbs/yr for chloride, and includes load limits for 3 separate sectors:

  • Waste Load Allocations (WLAs) from permitted, point discharges:  Includes MS4s, process water discharges, industrial discharges, construction site runoff, and future growth).
  • Load Allocations (LAs) from nonpoint sources:  Includes primarily areas outside of MS4 boundaries, the drainage areas to industrial stormwater outfalls, or from background levels.
  • Margin of Safety (MOS):  Defined as 10% of the total TMDL, set aside to account for uncertainty in the relationship between pollutant loads and water quality.

Sediment TMDL

For sediment load, the contributing sources DEQ 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.

DEQ recognizes 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.  The agency 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:  DEQ expects the current Virginia Stormwater Management Program (VSMP) regulations to, 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.  TMDL 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”.  DEQ anticipates using stream restoration, stream bank stabilization, and other BMPs that reduce stormwater runoff as part of these Implementation Plans, and stakeholders will have the opportunity to participate in plan development.  Stay tuned for more information on this process!

Chloride TMDL

For chloride load, the existing levels are attributed to the application of deicing salts – and this TMDL is the first in Virginia to focus on winter salt applications in an urban setting.  With public safety of critical importance, DEQ plans to achieve the chloride load reductions through performance-based BMP’s that will focus on training and technological improvements in applying deicing salt.  Rather than developing a traditional TMDL Implementation Plan, the chloride TMDL will be addressed by developing an Accotink Creek Salt Management Strategy (SaMS).  DEQ formed a Stakeholder Advisory Committee (SAC) at the beginning of the year and is in the process forming a Workgroup, with the first meeting anticipated to take place in the August/September timeframe.  You can read more about the SaMS here.

Wetland Studies and Solutions is familiar with the different TMDLs in place for watersheds across the Mid-Atlantic, and our water resource engineers regularly work with clients to accommodate TMDLs on project sites.[SB1] 

 [SB1]I added this – is it true?  If not, what else can we say about our broad experience with TMDLs that will show that we are the company to call if a client has questions about this? 

For more information about the Accotink Creek TMDLs or how this new regulation will affect your projects, please contact Frank Graziano in our Gainesville office.

Check out past issues in the Field Notes Archive.

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