Living with a Large Reduction in Permited Loading by Using a Hydrograph-Controlled Release Scheme

Conrads, Paul A.; Martello, William P.; Sullins, Nancy R.

doi:10.1007/978-94-017-0299-7_10

Cited by 1 publication

(2 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For this purpose, we estimated 7Q10 in both seasons, i.e., December to April and August to October. This approach of seasonal analysis is more practical and consistent with the USEPA's TMDL policy (Conrads et al, 2003). The estimated 7Q10 (1.9 m 3 s -1 ) using log-Pearson III distribution and 7-day consecutive average annual low streamflow corresponding to different El Niño phases (marked with triangles) are shown in the figure 9.…”

Section: Enso and Ammonia Permittingsupporting

confidence: 60%

“…Point-source discharge is regulated using National Pollutant Discharge Elimination System (NPDES) permits written by state environmental regulatory agencies for lake and stream water quality protection. To maintain stream water quality, some states have approved anti-degradation rules for water quality regulation (Conrads et al, 2003), which suggest utilizing a variable loading scheme, such as the hydrograph controlled release (HCR) approach, in order to utilize the increased assimilative capacity of streams during high flow periods. However, when extreme drought conditions persist for a long time, point-source dischargers relying on the HCR approach may have to hold their discharge for a long time due to extended low flow conditions in streams.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Incorporating Climate Variability for Point-Source Discharge Permitting in a Complex River System

Sharma¹,

Srivastava²,

Fang³

et al. 2012

Transactions of the ASABE

View full text Add to dashboard Cite

The conventional point-source discharge permitting approach, referred to as the National Pollutant Discharge Elimination System (NPDES), is based on either a regulatory low flow (hydrologic, biological, or seasonal) criterion or on a hydrograph controlled release (HCR) approach. Regulatory low flows are often estimated using empirical equations because of the lack of historical flow data. Overestimated low flows may threaten water quality protection, while underestimated low flows can result in uneconomical wastewater treatment. Since uncertainty in low flow estimations is caused by climate variability, uncertainty in the permitting process can be reduced through explicit incorporation of climate variability. Therefore, the objective of this study was to demonstrate how the NPDES permitting process can be improved through the incorporation of climate information. A dissolved oxygen (DO) model was developed for the Chickasaw Creek watershed located in southeast Alabama using the Loading Simulation Program C++ (LSPC) linked with a hydrodynamic and water quality model (EPD-RIV1). Models were calibrated and validated for flow, stream temperature, DO, and other water quality variables. DO and stream temperature variations were examined for historic, climate variability-causing events of La Niña and El Niño using a number of statistical criteria to develop toxicity-based and DO-based criteria for ammonia. The analysis identified December to April for El Niño as periods of high assimilation (28% higher as compared to the current assimilation). Similarly, August to October for La Niña was identified as a period of high assimilation, but with a higher degree of variability. May to July for La Niña and August to October for El Niño were identified as periods of restrictive point-source discharge. Analysis suggested that El Niño Southern Oscillation (ENSO) predictions provide sufficient warning for the impending drought for reducing point-source discharges because low flow in summer months is a function of winter and spring sea surface temperature, precipitation, and streamflow due to its autocorrelation and cross-correlation characteristics. Overall, the research demonstrated the usefulness of integrating climate information with NPDES permitting.

show abstract

Section: Enso and Ammonia Permittingsupporting

confidence: 60%

mentioning

confidence: 99%