Research Notes
- Past readings: http://drekbeach.org/api/fullSummaries
- Beach water quality: https://data.cityofchicago.org/Parks-Recreation/Beach-Water-Quality-Automated-Sensors/qmqz-2xku
- Beach weather station: https://data.cityofchicago.org/Parks-Recreation/Beach-Weather-Stations-Automated-Sensors/k7hf-8y75
- Park events: https://data.cityofchicago.org/Events/Chicago-Park-District-Event-Permits/pk66-w54g
These are notes taken from Chicago Park District.
- Lab methods look at fecal indicators to determine the potential of E. Coli levels.
- Beach advisories get posted at 235 parts per million (ppm) as recommended by EPA.
- Sampling methods
- Samples are taken at least 5 days a week
- If there is a high sample late in the week, Parks will resample on the weekends (e.g., Friday tests will come back on Saturday, if high, they’ll visit on Saturdays)
- Two samples are taken 50 feet from each other for each beach.
- Per #20, there is sometimes large disagreements between the two readings. The geometric mean is still used and it can take as much as 20 readings to get a stable estimate for any given location (per EPA).
- Samples are taken at least 5 days a week
- Built by US Geological Survey and Michigan State
- They looked at day-of-summer as part of the model
- Sometimes there are localized issues (e.g., Rainbow Beach had a stormwater problem)
- Have only used own-data, haven’t used other data sources
During the summer of 2015, Chicago Park District piloted a new, expensive form of testing for E. Coli bacteria by trying to detect DNA fragments in the water. This new test has a turn-around time that returns results within the day. It was piloted at 5 of Chicago's beaches. However, this method is very expensive. Likewise, the DNA and Lab Culture test did not always agree.
The lab data currently contains DNA testing data and those lab results should be removed from the analysis since they are expressed in different units. This method has a threshold of over 1,000 ppm before an advisory is issues.
Economic and Health Risk Trade-Offs of Swim Closures at a Lake Michigan Beach
This paper presents a framework for analyzing the economic, health, and recreation implications of swim closures related to high fecal indicator bacteria (FIB) levels. The framework utilizes benefit transfer policy analysis to provide a practical procedure for estimating the effectiveness of recreational water quality policies. Evaluation criteria include the rates of intended and unintended management outcomes, whether the chosen protocols generate closures with positive net economic benefits to swimmers, and the number of predicted illnesses the policy is able to prevent. We demonstrate the framework through a case study of a Lake Michigan freshwater beach using existing water quality and visitor data from 1998 to 2001. We find that a typical closure causes a net economic loss among would-be swimmers totaling $1274−37 030/day, depending on the value assumptions used. Unnecessary closures, caused by high indicator variability and a 24-h time delay between when samples are taken and the management decision can be made, occurred on 14 (12%) out of 118 monitored summer days. Days with high FIB levels when the swim area is open are also common but do relatively little economic harm in comparison. Also, even if the closure policy could be implemented daily and perfectly without error, only about 42% of predicted illnesses would be avoided. These conclusions were sensitive to the relative values and risk preferences that swimmers have for recreation access and avoiding health effects, suggesting a need for further study of the impacts of recreational water quality policies on individuals.
Sharyl J. M. Rabinovici ,* Richard L. Bernknopf , and Anne M. Wein U.S. Geological Survey, Western Geographic Science Center, 345 Middlefield Road MS 531, Menlo Park, California 94025 Don L. Coursey Irving B. Harris Graduate School of Public Policy, University of Chicago, 1155 East 60th Street, Chicago, Illinois 60637 Richard L. Whitman U.S. Geological Survey, Lake Michigan Ecological Research Station, 1100 North Mineral Springs Road, Porter, Indiana 46304 Environ. Sci. Technol., 2004, 38 (10), pp 2737–2745 DOI: 10.1021/es034905z Publication Date (Web): April 8, 2004 Copyright © 2004 American Chemical Society
