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have been modified in the model to reflect current conditions. Table 3 shows the modeled rates of these high capacity wells. High capacity wells beyond two miles retain the original pumping rates assigned to them in the Metropolitan Council’s 2014 modeling effort. Well usage is also addressed in Part 2 of this chapter. Water Quantity Data Elements Surface water quantity– The Minnesota River and Mississippi River are the major discharge features located within the domain of the model developed for this project. Numerous smaller discharge features havebeen added to the model domain and are explained in greater detail in the Metropolitan Council’s technical report for the Metropolitan Model (May 2014). Groundwater quantity- Review of groundwater appropriations permits in the State Water Use Data System ( SWUDS) databasewas performed to identify high capacity wells in the area that might affect delineation of the wellhead protection area. Most high capacity wells as of 2014 were includedin the Metropolitan Council’s model. High capacity wells within two miles of the Centerville wells were updated in the model for the purposes ofthis delineation effort and are listed in Table 3. The City of Centerville we modeled at the rate outlinedin the wellhead protection rules, based onhistorical or projected within with 5 yearsof the current date. Modeled Centerville wellrates are shown in Table 2. Water Quality Data Elements Surface water quality– Major surface water features in the area, such as the Minnesota River and Mississippi River, which are in direct hydraulic connection with the Prairie du Chien and Jordan aquifers, serve as flow boundaries within select layers of the Metropolitan Model. The Prairie du Chien and Jordan aquifers are also in connection with more localized streams and lakes, as documented in the Met Council model report (May 2014). Since these major rivers are points of drainage fromthe aquifers, the quality ofwater in these rivers does not playa large role in Centerville’s water quality. More pertinent is the quality of stormwater that infiltrates into the capture zones forthe City’s wells. Surface water quality will be addressed in greater detail in the updated Part 2 plan. Groundwater quality– Results ofroutine monitoring ofthe Centerville wells are contained within the files ofthe MinnesotaDepartment of Health. Historical monitoring has shown that the water qualitywithin the Jordan aquifer in Centerville is generally of excellent quality. Nitrates levels in Centerville’s wells remain low(less than 1.0 mg/L), indicating that nitrates-contaminants from turf fertilization is not impacting groundwater quality. Sampling of tritiumhas taken place at Centerville Wells 1 and 2. Tritiumis an isotope ofhydrogen that was released into the atmosphere during the above-ground testing of nuclear weapons in the early 1950s. While harmless, the presence of tritiumin aquifers indicates that someportion ofthe water was in contact with the atmosphere within the past 60 years. A tritiumlevel of1 tritiumunit (TU) or greater is an indication that these aquifers are somewhat vulnerable to contamination. The tritiumlevels range between non-detection (<0.8 TU) in Well 1 to 2.6 TU in Well 2. 6