Karen Kline

Applications of Microbial Source Tracking in the TMDL Process

The US Environmental Protection Agency’s Total Maximum Daily Load (TMDL) program is frequently cited as a primary driver in the development of microbial source tracking (MST) techniques. As MST techniques continue to mature, it is prudent to identify those areas where further MST-related research is most likely to contribute to the efficient development and implementation of bacterial TMDLs. The objectives of this chapter are to review the basic phases in the TMDL process, to describe current applications of MST within these stages, to identify research needed to increase MST application, and to discuss opportunities for the expanded use of MST data within the TMDL process.

Hydrometeorological and Physicochemical Drivers of Fecal Indicator Bacteria in Urban Stream Bottom Sediments

High levels of fecal indicator bacteria (FIB) are the leading cause of surface water quality impairments in the United States. Watershed-scale models are commonly used to identify relative contributions of watershed sources and to evaluate the effectiveness of remediation strategies. However, most existing models simplify FIB transport behavior as equivalent to that of dissolved-phase contaminants, ignoring the impacts of sediment on the fate and transport of FIB. Implementation of sediment-related processes within existing models is limited by minimal available monitoring data on sediment FIB concentrations for model development, calibration, and validation purposes. The purpose of the present study is to evaluate FIB levels in the streambed sediments as compared to those in the water column and to identify environmental variables that influence water and underlying sediment FIB levels. Concentrations of and enterococci in the water column and sediments of an urban stream were monitored weekly for 1 yr and correlated with a variety of potential hydrometeorological and physicochemical variables. Increased FIB concentrations in both the water column and sediments were most strongly correlated with increased antecedent 24-h rainfall, increased stream water temperature, decreased dissolved oxygen, and decreased specific conductivity. These observations will support future efforts to incorporate sediment-related processes in existing models through the identification of key FIB relationships with other model inputs, and the provision of sediment FIB concentrations for direct model calibration. In addition, identified key variables can be used in quick evaluation of the effectiveness of potential remediation strategies.

Scale-dependent impacts of urban and agricultural land use on nutrients, sediment, and runoff

We coupled a spatially-explicit land use/land cover (LULC) change model, Dinamica EGO, (Environment for Geoprocessing Objects), with the Chesapeake Bay Watershed Model (CBWM) to project the impact of future LULC change on loading of total nitrogen (TN), total phosphorous (TP) and total suspended solids (TSS) as well as runoff volume in the watersheds surrounding Virginias Shenandoah National Park in the eastern United States. We allowed for the dynamic transition of four LULC classes, Developed, Forest, Grasses (including both pasture and hayfields) and Crops. Using 2011 as a baseline scenario and observed differences in LULC between 2001 and 2011, we estimated the temporal and spatial patterns of LULC change as influenced by physiographic and socio-economic drivers 50 years in the future (2061). Between transitions of the four LULC classes, the greatest absolute change occurred between the gain in total Developed land and loss in total Forest. New Developed land was driven primarily by distance to existing Developed land and population density. Major findings on the effect of LULC change on watershed model outputs were that: the impact of LULC change on pollutant loading and runoff volume is more pronounced at finer spatial scales; increases in the area of Grasses produced the greatest increase in TP loading, while loss of Forest increased TN, TSS, and runoff volume the most; and land-river segments with a greater proportion of Developed or a smaller proportion of Forest in the 2011 scenario experienced a greater change in runoff than other land-river segments. Results of this study illustrate the potential impact of projected LULC change on nutrient and sediment loads which can adversely impact water quality. Studies like this contribute to a broader understanding of how ecosystem services such as fresh water respond to LULC change, information relevant to those in planning and watershed management.

Developing Sediment Load Thresholds Protective of Aquatic Life

Abstract. A method was developed for setting target Total Maximum Daily Load (TMDL) sediment loads in non-tidal watersheds of Virginia that directly relates biological conditions with sediment load levels. The new method is based on a modification of methodology developed by the state of Maryland which simulated sediment loads using Chesapeake Bay Watershed Model procedures. The modified method is proposed for use in several case study watersheds in Virginia using the GWLF model. The biological condition is represented by the average Virginia Stream Condition Index (VSCI), while sediment is represented as the existing sediment load normalized by the corresponding load under an all-forest condition. The existing sediment load in any given watershed divided by the corresponding sediment load simulated under an all-forest condition, results in an all-forest load multiplier, AllForX. When AllForX is regressed against VSCI for a number of healthy watersheds surrounding a particular impaired watershed, the developed relationship can be used to quantify the value of AllForX for the biological health threshold (VSCI = 60) used to assess aquatic life use impairments in Virginia. The TMDL is then calculated as the value of AllForX at the VSCI threshold times the all-forest sediment load of the impaired watershed. Since a number of watersheds are used to set the regression, a confidence interval around the threshold can also be quantified and used to calculate the margin of safety in the TMDL equation. The relationship between AllForX and the biological condition is validated with plots and regressions between AllForX and various independent sediment-related habitat metrics.

Phased TMDLs in Mining Areas of Virginia

Current EPA guidance recommends that the phased TMDL approach be used in situations “where limited existing data are used to develop a TMDL and the State believes that the use of additional data or data based on better analytical techniques would likely increase the accuracy of the TMDL load calculation and merit development of a second phase TMDL”. This paper discusses the data uncertainties leading to the use of a phased TMDL in a specific coal mining watershed in southwestern Virginia. The TMDL addressed a benthic impairment that was linked through use of a stressor analysis with excessive sediment (TSS) and total dissolved solids (TDS).

PEMSEA Partnership for Watershed Management in East Asia

The Partnership in Environmental Management for the Seas of East Asia (PEMSEA) has been working to promote implementation of site-specific river basin and coastal management programs in Manila Bay and Jakarta Bay, among others, through “twinning arrangements” with U.S. personnel involved with pollution reduction in the Chesapeake Bay. PEMSEA partnered with the University of Maryland’s Center for Environmental Science (UMCES) and Virginia Tech’s Center for Watershed Studies to develop a training workshop for participants from the Philippines, Indonesia, the People’s Republic of China, and the Republic of Korea. The workshop initially focused on the participants who provided examples of good environmental management practices and challenges in their individual countries. Following this, the training team led participants through a step-by-step process of developing a Total Maximum Daily Load (TMDL), which is an integral part of many watershed management efforts in the U.S. The TMDL portion of the workshop included facilitator- led discussions that explored how the process might apply to watershed planning in East Asia for smaller watersheds. The workshop culminated in the development and presentation of rudimentary TMDLs by two teams of participants. One team addressed the Meycauayan-Marilao-Obando watersheds in Manila and the other addressed the Ciliwung River watershed in Jakarta.