1. CE5504 – Surface Water Quality Modeling CE5504 Surface Water Quality Modeling Spring Semester 2011 Lab 2. Loads

2. Little loads, like those from toads, Grow bigger when from horses. And on through us, I fear they must, Foul the water courses. Ode to the Load

3. The Clean Water Act and TMDLs In 1972, the Federal Water Pollution Control Act was amended requiring, in part, a minimum level of control based on available treatment technologies. Where implementation of those technologies does not result in water quality standards being met, Section 303 of the Act requires that regulators, Establish Total Maximum Daily Loads (TMDLs) for these waters at levels necessary to meet applicable water quality standards, accounting for seasonal variations and with a margin of safety to reflect lack of certainty about discharges and water quality. This can be accomplished through a modeling approach where C represents the water quality standard and W represents the ‘necessary level’ of load, e.g.

4. Identifying Loading Sources CE5504 – Surface Water Quality Modeling Example - Deer Lake, Michigan sediments tributaries WWTP atmosphere

5. The Mass Balance CE5504 – Surface Water Quality Modeling For a reactive constituent in completely-mixed lake, (all terms having units of mass · time -1, e.g. g · d -1 ) load outflow reaction point source, tributaries: Q · C, m 3 ·d -1 x g·m -3 nonpoint terrestrial source: UAL·A, g·m 2 ·d -1 x m 2 nonpoint atmospheric source: J·A, g·m 2 ·d -1 x m 2 sediment source: J·A, g·m 2 ·d -1 x m 2

6. Deer Lake Loads CE5504 – Surface Water Quality Modeling load, mass · time -1, g · d -1 Consider challenges in quantifying these, e.g. (1)accounting for seasonal variations and (2)establishing a margin of safety

7. Steady State C, Constant Loads and, at steady state, where W is constant and quantified as shown in the previous slide.

8. Time Variable C, Time Variable Loads dividing both sides by V and applying numerical integration, How may we describe W(t) ?

9. Time Variable C, Idealized, Time Variable Loads then an initial concentration is calculated, and the integration proceeds with W = 0 Impulse load (spill) 0

10. Time Variable C, Idealized, Time Variable Loads where an initial concentration corresponding to prior conditions is specified Step load (new continuous source)

11. Time Variable C, Idealized, Time Variable Loads where an initial concentration corresponding to prior conditions or W base is specified Linear load

12. Time Variable C, Idealized, Time Variable Loads where an initial concentration corresponding to prior conditions or W e is specified Exponential load

13. Time Variable C, Idealized, Time Variable Loads where an initial concentration corresponding to prior conditions or W bar is specified Sinusoidal load

14. Quantifying Tributary Loads  USGS  clueless Approach: develop the relationship between C and Q, e.g. as expressed in a C/Q plot. Apply that relationship to derive C values from the USGS Q data base and then use W(t) = Q·C to calculate the load. a b C Q

15. C/Q for TSS in Ontonagon River, Lake Superior CE5504 – Surface Water Quality Modeling linear bipartite ascending - descending

16. C/Q for Chloride in Nine Mile Creek, Onondaga Lake CE5504 – Surface Water Quality Modeling inverse linear plot two different historical intervals

17. C/Q for TSS in Onondaga Creek, Onondaga Lake CE5504 – Surface Water Quality Modeling logC plot

18. C/Q for Total Phosphorus in Onondaga Creek, Onondaga Lake CE5504 – Surface Water Quality Modeling log – log plot two different stations