AVAILABILITY OF AQUIFER PROPERTY DATA IN THE DENVER BASIN

The four principal bedrock aquifers of the Denver Basin and the overlying alluvial aquifer are a vital water resource for Front Range communities in Colorado. To assist decision makers manage these resources, aquifer property data were collected for the South Platte Decision Support System (SPDSS) being developed by the State’s Division of Natural Resources.

Transmissivity (T), hydraulic conductivity (K), storativity (S), and specific yield (Sy) data were collected from published and un-published sources and include aquifer pumping tests, specific capacity tests, and laboratory analyses. In addition, a SPDSS monitoring well was drilled, core samples collected, and the Arapahoe Aquifer tested about 10 miles east of Denver International Airport. Data were screened, converted to consistent units and added to a database. The data collection efforts yielded over 1,600 data values for T, K, S, and Sy for the bedrock and overlying alluvial aquifers.

Point value maps and summary statistics were produced for each data type by aquifer. The maps highlight the distribution of the data and revealed that the majority of the data for the bedrock aquifers reside near the Denver Metro area, and storativity data are scarce for most of the basin. The maps also help demonstrate the heterogeneity of the bedrock aquifers. Analysis of the lab data revealed uncertainty in historical data due to unknown sampling, preservation, and analytical methods. Specific capacity data were converted to transmissivity as a cost-effective means to filling data gaps in parts of the Denver Basin.

Much of the data collected for the SPDSS had been previously published in reports which are not easily available to the public. Now that the data have been combined into a single database they will be an important and readily available tool to assist the State and others in making informed water resources decisions regarding the South Platte River Basin's aquifers.