Sustaining Central Sands Water Resources
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This document aims to provide a common framework for scientists to communicate within and across disciplines regarding future water resource management throughout the Central Sands of Wisconsin. It reviews interdisciplinary research pertinent for 1) understanding how the land cover and land use of the area has changed over time; 2) documenting long-term changes in regional groundwater levels, lake levels, and stream baseflows and related meteorological variables; and 3) investigating water resource management strategies and frameworks that have been implemented in other regions of the United States and throughout the world. Reviewed research shows that the Central Sands aquifer has been a primary resource for agriculture, human water supply, industrial and stock supplies, recreational activities and ecosystems. Land use and land cover has changed from predominantly prairies, savannahs, and forests in the early 1800?s to present-day agricultural, forested and urban areas. From 1948 to 2006, average annual temperatures throughout the region have increased 1 to 2�C and growing seasons have lengthened by 15 to 20 days resulting in increased climate-driven average annual evapotranspiration. During this same time period, total annual precipitation has increased between 5 and 15 cm leading to an increase in climate-driven recharge between 5 and 10 cm, despite increases in average annual evapotranspiration. Meanwhile, regional groundwater levels, lake levels and baseflow in streams have declined over the last several decades with the greatest declines in levels and flows close to the groundwater divide and in streams near groundwater pumping wells. The declines in groundwater and associated surface water levels have been understood as a reduction in recharge estimated between 4.5 and 14.2 cm per year depending on the location in the aquifer. The discrepancy between long-term climate trends and surface water and groundwater observations suggests that land use practices, such as irrigated agriculture,influence groundwater and associated surface water levels. The paucity of long-term groundwater and surface water datasets has limited analyses that can be conducted without the use of more complex groundwater flow models. Drainage ditches throughout the region have potential to lower local groundwater levels and shorten groundwater flow paths. Regional effects of drainage ditches have not been conducted. A shared-vision planning framework and potential strategies for water resources management are summarized to encourage discussions aimed at implementation of solutions with the greatest potential of success toward meeting the goals previously defined during stakeholder conversations. Future groundwater and surface water management will require comprehensive modeling that can test alternative land use and land management strategies. Key knowledge gaps that currently hinder a comprehensive modeling approach include land management influences on rates of evapotranspiration, data collection and ecosystem valuation. Modeling would need to be conducted on a transient time scale to accommodate annual and inter-annual variations in weather and dynamic land management practices. Given the comprehensive review of the state of water resources science in the Central Sands along with a framework and strategies that have been implemented in other areas of the nation and the world, this document aims to support future strategic planning and implementation of water resources management in the Central Sands region of Wisconsin.