Cooperative design of a water quality monitoring system for the Big Thompson River Watershed, Colorado
Date
1999
Authors
Greve, Adrienne I., author
Loftis, Jim C., advisor
Ward, Robert, committee member
Laituri, Melinda, committee member
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Abstract
Water from the Big Thompson River and the Colorado-Big Thompson Project (a trans-mountain diversion of Colorado River water to the Big Thompson River) is a valuable resource to the North Front Range region of Colorado. The water is utilized for many purposes (e.g. municipal, irrigation, industrial, recreation, and ecosystem health). Over half a million people depend on the Big Thompson system for drinking water. In recent years a slow decline in water quality has been observed at some locations, particularly in reservoirs lower in the watershed. This trend, coupled with increased pressure to provide accurate data about water quality, has lead a group of stakeholders in the Big Thompson Watershed to seek a better way in which to monitor and manage their water, through cooperation. Stakeholders within the Big Thompson Watershed, who make up a group called the Big Thompson Watershed Forum (BTWF), formed a partnership with Colorado State University to design a water quality monitoring network. The design process was broken down into five steps: objectives, variables, monitoring locations, sampling frequency, and cost analysis. Each step was completed in a cooperative manner, through a series of meetings with BTWF members. The meetings provided an opportunity for members of the BTWF to shape the monitoring system based upon concerns and priorities specific to the watershed. The resulting water quality network is governed by five objectives. The objectives address regulatory requirements within the watershed, eutrophication of reservoirs, and the estimation of loads, spatial trends, and temporal trends. A variable list of 38 water quality parameters was defined as the minimum group of variables that meet the informational goals laid out in the objectives. The list included 12 inorganic variables, nine metals, five organic parameters, seven microbiological variables, and five field parameters. Monitoring locations were defined based on the objective list, already existing monitoring sites, and watershed hydrology (e.g. mixing distance, confluence locations, diversions). Thirty-nine monitoring locations were chosen; 29 moving water sites and 10 reservoir sites. Each site was given a priority rating of high or low. The group of 31 high priority sites is the smallest network that satisfies the needs of all BTWF participants. The seven low priority monitoring locations will be sampled if financially feasible. Sampling frequency was determined on a seasonal basis. Three seasons were determined based on annual flow and water temperature cycles. It was originally hoped that historical data could be used to estimate background variability, allowing the sample size required for a specified level of accuracy in mean and trend detection to be determined. Only 11, of the 38 variables on the variable list, had historical data available, and only three, of the 11, had enough data to accurately estimate background variability. Sampling frequencies for variables with inadequate historical data were based a maximum frequency set for each season. During seasons one and two, no variable is to be sampled at a frequency higher than twice a month except for biological parameters. The maximum frequency during season three is monthly. The cost estimate step was utilized as a feasibility check on the monitoring program. The aim for the cooperative monitoring program was more thorough information for the same or less cost. If the monitoring program cost exceeded the sum of all current monitoring budgets, adjustments were made in variables, monitoring sites, and sampling frequency. The final cost estimate was $405,259.00 per year, roughly the same as the $401,500.00 currently spent. In order for an undertaking such as this design and monitoring program to succeed, all participants must be willing to compromise and devote large amounts of time in order to allow for a truly cooperative effort. Those individuals most active in the design process typically represented local entities. The resulting monitoring network therefore gave higher priority to local water quality concerns, highlighting the differences between local informational needs and those defined by state and federal governments. The monitoring system currently includes a set of objectives, variable list, monitoring network, and sample frequency. They have been developed, discussed, and agreed upon by all BTWF participants. The completion of the monitoring network indicates that the BTWF is on its way towards the final goal of a long-term monitoring program operated by, and benefiting all agencies involved.
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Subject
Water quality -- Colorado -- Big Thompson River Watershed -- Measurement
Water quality monitoring stations