Evaluating Drought Vulnerability of Small Community Surface Water Supply Systems in the Midwest

This report presents approaches and data availability for evaluating the drought vulnerability of small community water supply systems in the Midwest that obtain water from surface water bodies, such as rivers, streams, natural lakes, and man-made reservoirs. A description is provided of the various types of surface water sources from which 320 small community systems in the Midwest, each serving 10,000 or fewer people, obtain their water. The small community surface water system most commonly obtains its supply from one or two small impounding reservoirs. However, a substantial number of communities instead obtain their water from either direct river withdrawals or off-channel storage of water withdrawn from streams and rivers. Sixty of these 320 small community surface water systems were interviewed to gather information on the availability of data to determine the drought vulnerability of these systems. Although hydrologic and physical data exist for evaluating many of these systems, relatively few of the interviewed system managers could provide such pertinent information. A summary of selected hydrologic data is provided that can be used to determine the relative severity of major historical drought periods for various portions of the Midwest. Focus is given to historical droughts and available data for the southern portion of the Midwest where most surface water supply systems are located, comprising parts of Kansas, Missouri, Iowa, Illinois, Indiana, and Ohio. Geographic differences in drought severity are described, as is the influence of the physical characteristics of a water supply on the “critical” drought duration that a community must consider. Basic water budget analyses of water supplies and data needs are presented. Reservoir capacity measurements and estimates of inflow are the most critical data in reliable assessment of water supply adequacy. Depending on data availability, estimation of inflows may be straightforward to highly uncertain. For water supply systems that withdraw directly from a stream or river, the existence of long-term stream gage data on that river is particularly crucial to evaluate supply adequacy, and such data for larger streams and rivers are often available. With impounding reservoirs, which are typically located on smaller streams, data for that stream may often not exist; however, data from a “surrogate” gage that is considered to be hydrologically similar are often sufficient to estimate water supply yield. Systems that use off-channel reservoirs often withdraw water from smaller streams that do not have data for accurate depiction of their yield, and these systems also appear to be the most vulnerable to severe drought conditions. Case studies are presented to provide examples of yield calculations and innovative approaches that selected small communities have undertaken for addressing drought vulnerability. The role of demand management (drought response and water conservation) in evaluating drought vulnerability is also presented. If hydrologic data and basic physical data such as storage capacity are lacking, it may be difficult for either system managers or experienced professionals to estimate a community system’s yield and potential drought impacts, particularly for off-channel reservoir and low channel dam systems. However, managers should attempt to understand the type of drought period likely to test the adequacy of the available supply and can begin recording basic system observations, such as daily withdrawal records and reservoir drawdown, in a readily-accessible form that will be useful for future evaluations.published or submitted for publicationis peer reviewe

The Next Frontier: Making Research More Reproducible

Science and engineering rest on the concept of reproducibility. An important question for any study is: are the results reproducible? Can the results be recreated independently by other researchers or professionals? Research results need to be independently reproduced and validated before they are accepted as fact or theory. Across numerous fields like psychology, computer systems, and water resources there are problems to reproduce research results (Aarts et al. 2015; Collberg et al. 2014; Hutton et al. 2016; Stagge et al. 2019; Stodden et al. 2018). This editorial examines the challenges to reproduce research results and suggests community practices to overcome these challenges. Coordination is needed among the authors, journals, funders and institutions that produce, publish, and report research. Making research more reproducible will allow researchers, professionals, and students to more quickly understand and apply research in follow-on efforts and advance the field

Data for Assessing Drought Vulnerability of Illinois' Community Surface Water Systems

Illinois Department of Natural Resourcespublished or submitted for publicationis peer reviewe

Operating Rules for Improving the Firm Yield of an Off-Stream Blending Reservoir System Used for Reducing Nitrate in Drinking Water and Drought Storage

Community water supply systems dependent upon surface water sources susceptible to both low flows contaminant concentrations exceeding drinking water quality standards can use off-stream blending reservoirs (OSBR) to increase their water supply reliability and avoid investments in expensive treatment technology. The water quality operating rules (WQOR) that water supply systems use to regulate inflow into their OSBR affect their firm yield (i.e., the amount of water guaranteed for supply). The impacts of three types of WQOR on firm yield are explored from a retrospective planning perspective using a simulation model with a daily time step. The water supply system in Pontiac, Illinois, which utilizes its OSBR to meet an internal nitrate-N concentration guideline of 8.0 mg/L through blending, is modeled as a case study. Using streamflow and nitrate-N data from May 1979 to April 1999, a firm yield of 2.21 mgd (million gallons per day) is attained under its current WQOR in which the OSBR is only filled when the concentration in the Vermilion River is less than or equal to 4 mg/L (River Concentration Rule). If the rule is modified to allow the inflow of water of any concentration into the reservoir when the reservoir concentration is at or below 4 mg/L, the yield rises to 2.32 mgd (Reservoir Concentration Rule). When a constraint limiting the reservoir inflow to a concentration of 8 mg/L or lower is added to the Reservoir Concentration Rule, the yield rises to 2.67 mgd (Hybrid Concentration Rule). This increase indicates that limiting the inflow of high-nitrate water into the OSBR can increase the firm yield. Yet, in many cases, a moderate relaxation of water quality constraints can elevate the firm yield as long as the system is willing to invest in the additional algae control effort which may result from such a decision. Under all three WQORs defined above, the critical period that limits the firm yield consists of a drought in 1988 followed by a two- or three-year period of above-normal nitrate-N concentrations in the river. The potential effects of reservoir nitrate sinks and nutrient management practices on the firm yield are also quantified. When nitrate losses at a hypothetical first-order rate of just 0.02 ft/d at 20?? C are considered, the firm yields under the three WQORs increase to 2.39, 3.56 and 3.24 mgd, respectively. Meanwhile, a uniform 20 percent decrease in the nitrate-N concentration in the Vermilion River leads to 43, 39 and 33 percent increases in the firm yield, respectively. The firm yields attained with the three WQORs all exceed the system???s 2005-2009 average daily demand of 1.95 mgd. Yet, a sensitivity analysis demonstrates that the firm yield can fall below this demand when accounting for the uncertainty of low flows, net evaporation and the reduction of raw water nitrate-N concentrations to less than 8.0 mg/L when blending takes place. A further assessment of the system???s vulnerability to a water shortage, which should include an estimate of the nitrate loss rate in the reservoir, is warranted

Water Supply Assessment for Kaskaskia River Watershed Development: Phase 1 Technical Report

published or submitted for publicationis peer reviewe

Watershed Supply Assessment for Kaskaskia River Watershed Development: Phase I Technical Report

This document was prepared for the Kaskaskia Basin Water Supply Planning Committee to aid their development of a plan for meeting the future growth of water supply demands within the basin. It contains background information to provide an overview of management criteria and an understanding of the constraints and policies used in conducting analyses and making decisions concerning water use within the Kaskaskia Basin. This report describes the following work of the Illinois State Water Survey, funded by the Illinois Clean Coal Institute: Retrieval and summation of existing information regarding surface water and groundwater availability in the region. This report of existing information will also include information provided by the Illinois Department of Natural Resources-Office of Water Resources (IDNR-OWR) addressing the water supply storage and allocations from Carlyle Lake and Lake Shelbyville. Development of surface and groundwater hydrologic models to simulate the hydrology of the Kaskaskia River watershed, water levels in the federal reservoirs, and selected local groundwater resources. Specific models developed include: a Streamflow Accounting Model, a Watershed Simulation Model and Reservoir Routing Models, and a set of Groundwater Flow Models. Major portions of this report deal with a summary of existing information. The models developed in this study will be applied to water use planning scenarios in the ongoing Phase II effort funded by the IDNR-OWR. Only limited results are available for inclusion in this report.published or submitted for publicationis peer reviewe