Real-time monitoring, modeling and management of selenium drainage discharges in the Delta Mendota Canal
Can forecasts of downstream assimilative capacity be developed for selenium contaminated water flowing into the DMC to meet State Water Quality objectives?
Can electrical conductivity be used as a surrogate for selenium in the development of a water quality forecasting and decision support system?
Will the Firebaugh Canal Water District, whose land drains into the canal, have sufficient confidence in the system to adopt it at the end of the project?
Need and Benefit
The Delta-Mendota Canal (Canal) delivers Central Valley Project (CVP) water for farms and wildlife areas in central California. The current limit for selenium in wetland water supply channels is a monthly average of 2 parts per billion (pbb).
Selenium contaminated ground and surface water enters the DMC throughout the year. However, this contamination is a problem during the winter months and early spring when the assimilative capacity of the DMC is low.
Six closed drain sumps located in the Firebaugh Canal Water District were installed in 1953 to mitigate the canal's interruption of existing drainage channels. The water from the sumps, though low in volume, is rich in selenium and other trace elements. The loads of selenium from each sump have been monitored for many years.
Reclamation is conducting a detailed survey of the contamination in the canal. We are collecting daily composite samples of water from three locations in the canal to understand the temporal patterns of selenium contamination in response to our operation of the canal. This selenium monitoring program does nothing to solve the underlying problem.
When the selenium load entering the DMC exceeds the assimilative capacity (calculated based on a maximum allowable ambient selenium concentration of 2 ppb), the canal water should not be delivered directly to wildlife areas. Since the Canal is the primary source of water for these wildlife areas, it is imperative that Reclamation address this issue to meet its obligation under State and Federal regulations.
This proposal will be conducted in cooperation with the Danish Hydrological Institute, the Firebaugh Canal Water District and the San Luis and Delta Mendota Water Authority (SLDMWA). We will develop a model to predict basin ground water flow, drainage flow, and water quality dynamics, and to estimate real-time drainage production at each of the sumps along the Canal. A version of MIKE 11 (a one-dimensional [1D] hydrodynamic flow and water quality model) and a Kalman Filter subroutine will be used to develop continuous predictions of selenium concentrations in the Canal and Mendota Pool.
A planning study will be performed to demonstrate the potential of a real-time SCADA control system for the sumps that responds to selenium water quality forecasts to continuously meet selenium water quality objectives in the DMC. The final phase of the project will be technology transfer to the SLDMWA and testing the pilot decision support system.
Bureau of Reclamation Review
The following documents were reviewed by experts in fields relating to this project's study and findings. The results were determined to be achieved using valid means.
Slideshow of simualtion modeling results using Mike-SHE and Mike-11 (interim, PDF,
By Nigel Quinn
Publication completed on June 29, 2012