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51 the latter as such. Table 2-3 contains a complete list of water- load (TMDL) allocations, 70% of the DOTs ranked identifi- shed research priority areas and rankings. cation of valid monitoring methods as a research priority. Ranked lower, but still a priority area to more than 50% of the state DOTs were deicing agent selection criteria. The role 2.3. RUNOFF CHARACTERIZATION of total suspended solids (TSS) and dissolved organic carbon (DOC) in controlling dissolved metal concentration was also As illustrated in Table 2-4, the highest rankings among an area of interest and ranked 28th. Regulatory pressures are state DOT topic areas pertaining to highway runoff charac- more acute in some areas than in others; water quality prob- terization suggest the DOTs' interest in research that charac- lems due to urbanization and heavy metal concentration in terizes their responsibilities and where they should devote relation to or projected from total connected impervious area the most attention: in the watershed also was ranked relatively low (37th), but this rapid assessment technique is considered promising in Contribution of highway runoff to watershed loadings areas looking for creative and cost-effective approaches (a high or mid-level priority to 82% the DOTs; ranked to TMDL allocations and endangered species concerns. 7th), and Only one-half of the state DOTs indicated that they con- Threshold traffic densities below which certain pollu- duct stormwater monitoring, perhaps explaining the lower- tants in highway runoff can be considered negligible or than-anticipated level of interest in runoff characterization or irreducible and can be dispersed on roadsides (a high or receiving waters impact assessment. mid-level priority to 76% of DOTs; ranked 8th). Both of these research questions were characterized as high 2.4. IMPACTS TO RECEIVING WATERS priorities by more than 50% of the DOTs. To better answer such questions and to address requests of regulatory agencies Chemical, toxic, and physical impacts on aquatic biota of with relation to the National Pollutant Discharge Elimination stormwater discharges--topics at the top of many university System (NPDES) permits and to the total maximum daily researchers' lists--received only middling interest from DOT TABLE 2-3 Watershed research areas ranked in priority by state DOTs Number of State DOTs Ranking Each Research Area Research Areas Pertaining to Watersheds SCORE High Mid-level Low RANK Priority Priority Priority (3) (2) (1) WEIGHT 4 2 -1 Contribution of highway runoff to watershed 8 26 12 11 117 loadings Demonstrating the costs and benefits of 14 alternative, offsite, and watershed-based 17 21 9 101 stormwater mitigation Best methods for improving stream ecology 16 through water quality BMPsalternatives to 18 18 12 96 regulating runoff in urban areas Methodologies to determine where flow control of runoff volumes and high flow durations are 24 14 21 12 86 appropriate to prevent stream bank erosion in ultra-urban areas Characterization on a watershed basis and the 26 availability and prioritization of sites for 14 19 14 80 constructed wetlands The ability of watershed or regionally based enhancements of wet weather storage capacity 32 to improve baseline (high and low flow) 13 18 18 70 hydrology and ecological productivity downstream Water quality problems due to urbanization and heavy metal concentration in relation to or 37 8 21 20 54 projected from total connected impervious area in the watershed