Title 7 Natural Resources and Environmental Control
7400 Watershed Assessment Section
7410 TMDLs for the Naamans Creek Watersheds
1.0 Introduction and Background
1.1 Water quality monitoring performed by the Department of Natural Resources and Environmental Control (DNREC) has shown that Naamans Creek is impaired by high levels of bacteria and elevated levels of the nutrients nitrogen and phosphorous, and that the designated uses are not fully supported by water quality in the stream.
1.2 Section 303(d) of the Federal Clean Water Act (CWA) requires states to develop a list (303(d) List) of waterbodies for which existing pollution control activities are not sufficient to attain applicable water quality criteria and to develop Total Maximum Daily Loads (TMDLs) for pollutants or stressors causing the impairment. A TMDL sets a limit on the amount of a pollutant that can be discharged into a waterbody and still protect water quality. TMDLs are composed of three components, including Waste Load Allocations (WLAs) for point source discharges, Load Allocations (LAs) for nonpoint sources, and a Margin of Safety (MOS).
1.3 DNREC listed the Naamans Creek on several of the State’s 303(d) Lists and proposes the following Total Maximum Daily Load regulation for nitrogen, phosphorous, and Enterococcus bacteria.
2.0 Total Maximum Daily Loads (TMDLs) Regulation for Naamans Creek, Delaware
Article 1. The nonpoint source nitrogen load shall be capped at the 2000-2004 baseline level. This shall result in a yearly-average total nitrogen load of 228 pounds per day.
Article 2. The nonpoint source phosphorous load shall be capped at the 2000-2004 baseline level. This shall result in a yearly-average total phosphorous load of 13 pounds per day.
Article 3 .. The nonpoint source bacteria load shall be reduced by 78%. This shall result in reducing a yearly-mean bacteria load from 5.8E+10 CFU per day to 1.6E+10 CFU per day.
Article 4. Based upon water quality model runs and assuming implementation of reductions identified by Articles 1 through 3, DNREC has determined that, with an adequate margin of safety, water quality standards will be met in Naamans Creek.
Article 5. Implementation of this TMDL Regulation shall be achieved through development and implementation of a Pollution Control Strategy. The Strategy will be developed by DNREC in concert with a Naamans Creek Tributary Action Team, other stakeholders, and the public.
9 DE Reg. 1002 (12/01/05)