Fox River watershed investigation: Stratton Dam to the Illinois River: water quality issues and data report to the Fox River Study Group, Inc.

In addition to the water chemistry data and associated rate coefficients, standard data inputs are necessary to model water quality in a watershed.These include: elevation data, stream locations, soil types and properties, land cover, stream channel geometry, flow data and climate data (precipitation and temperature).Available data are presented in Chapter 2 of this report.Below is a summary of recommendations for additional data acquisition.• It is strongly recommended that the South Elgin gage (05551000) be reinstated as a continuous recording gage.The lack of flow data for many tributaries also will limit model capabilities, and establishing continuous recording gages is encouraged, particularly for those ungaged tributaries recommended for additional water chemistry sampling above.• The National Hydrography Dataset (NHD) high-resolution data are nearly completed for the lower Fox River watershed, but only low-resolution data are available for the upper Fox River watershed.Cost sharing with the USGS is a viable option to finalize the highresolution data for the entire watershed in a timely manner.• The State Soil Geographic Database SSURGO high-resolution soils information is available for only selected counties in the Fox River watershed: Kane, McHenry, DuPage, DeKalb, and Will Counties.Other counties in the watershed should be encouraged to work with the U.S. Department of Agriculture, Natural Resources Conservation Service to develop SSURGO data.viii • Precipitation data should be collected for every gaged watershed, with at least daily totals and preferably hourly data collected.Precipitation data are lacking in the lower part of the watershed. Modeling Considerations and Recommendations for Observed Water Quality IssuesThere are two aspects of water quality modeling, watershed loading and in-stream transport.Watershed loading models simulate the washoff and delivery of constituents from the land surface to the receiving stream, this process is driven by precipitation events.Receiving stream models simulate chemical interactions, mixing, and transport along the river system.These models may simulate steady low-flow conditions or changing flow conditions related to precipitation events.Results of watershed loading simulations serve as inputs to the in-stream modeling routines.Models and model resolutions chosen to represent the Fox River watershed should be selected to address issues and concerns of stakeholders, with adequate resolution and accuracy.The temporal and spatial resolution of the model(s) must be set to appropriately simulate the conditions related to the water quality issues.Loading of selected constituents can be aggregated for a large area (e.g., an entire tributary) or distinct smaller areas (sub-watersheds).A model can be customized to provide information that represents conditions averaged over several hundred feet or several miles of the river (spatial resolution).Models can simulate conditions averaged over a year, a month, a day, or an hour (temporal resolution).Models can be calibrated for a wide range of changing flows (unsteady flow) or for a limited range such as specified lowflow conditions (steady flow).The type of calibration data needed to customize a model or models depends on the spatial and temporal resolution desired of the results.Parameters from models calibrated using data from one system can be applied to a similar system to simulate various conditions, thus extending the utility of the data collected.Low dissolved oxygen levels, organic enrichment, pH, and algae blooms constitute water quality issues in the Fox River that are related to steady, low-flow conditions.Although the flow may be relatively stable, concentrations of these parameters change during the day and a model must be capable of simulating hourly changes.Furthermore, dissolved oxygen changes dramatically in the Fox River throughout the sequence of free-flowing areas and pooled areas, and this must be taken into consideration.Siltation, high fecal coliform levels, and nutrient loading from the Fox River watershed are best represented by unsteady flow conditions.Models are needed to simulate the delivery of these constituents from various land uses in the watershed under a variety of flow conditions.It is recommended that a flexible, modular framework be established for the Fox River watershed model.The model or models used should be in the public domain, well tested, and generally accepted for their reliability.The framework initially should consist of watershed loading models for major tributaries to the Fox River and a receiving stream model for the ix mainstem of the Fox River.The modular framework should be such that various components, e.g., the tributary watershed models, can be refined as data become available.The USEPA's BASINS model system provides tools for integration of GIS datasets and industry standard models such as HSPF, SWAT, and QUAL2E.It is recommended that the BASINS modeling framework be selected for the Fox River watershed, in particular, the HSPF model for watershed loading from tributaries to the Fox River.A QUAL2E (or similar) model may be used to address steady, low-flow conditions and diurnal dissolved oxygen variations on the mainstem of the Fox River.An unsteady flow model, such as HSPF, for the mainstem of the Fox River could be developed to address unsteady flow issues.Data assembled in the FoxDB and the various GIS datasets for the Fox River watershed provide a basis for setting up the model framework.It is suggested that the model framework be developed and the models calibrated to the extent possible using these data.Customized models then may be used to evaluate additional data needs and design an intensive monitoring program for model calibration.Datasets should be collected to validate the models, and an uncertainty analysis should be performed for parameters of major significance. Information Dissemination and Stakeholder InvolvementAs part of this collaborative effort to understand the watershed and protect its water resources, information dissemination and public education are important tasks.The ISWS will provide open access to all information developed by the ISWS.The Illinois Rivers Decision Support System Web site hosts the Fox River Watershed Investigation Web site.The Internet provides broad public assess to publications (publication database), data (FoxDB, which contains water chemistry and sediment chemistry sample data); and GIS mapping products for illustration of watershed features, as well as the full text of research reports.In the future, models customized for the Fox River watershed by the ISWS will be available through this portal, as will any educational or informational products developed.In addition to Internet accessibility, outreach should include meetings with stakeholders and collaboration with area water quality and engineering professionals. Future ConsiderationsIt is the ISWS vision that products developed through the Fox River Watershed Investigation will be a living resource for the public, researchers, engineers, planners, and policy makers.The database of water chemistry sample information should be updated routinely as monitoring continues.Models of the watershed should be in the public domain, available for use by other researchers and engineers.The monitoring program should continue, and a program of updating the FoxDB and model(s) should be established, with model results periodically compared with new data and refined.Ultimately, the study area should expand to include the entire Fox River watershed.The ISWS hopes to collaborate with the FRSG to provide sound science for watershed management and policy formation that will protect this valuable resource well into the future.x

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