Groundwater And Climate Change: South Washington Watershed District Prepares For New Challenges
Posted in East Metro Water Area Voices
June 13, 2016 by Angie HongLink to story online
Near the southeast corner of Inwood Ave. and County Rd. 10 in Lake Elmo, construction crews are busy moving dirt and pouring foundations for 130 new detached townhomes. The place is a hive of activity with contractors buzzing in and out throughout the day, digging trenches and laying pipe beneath roads that appear overnight. Further south, there are 11 residential developments currently under construction in Woodbury and another eight being built in Cottage Grove. Tractors are rolling, wood frames going up – signs advertise new restaurants, retail shops, and a school for the people coming here to live.Managing the impacts of development on water resources has been at the core of South Washington Watershed District’s mission since its inception in 1984. In the early years, a joint powers agreement was formed between five cities – Afton, Cottage Grove, Lake Elmo, Oakdale, and Woodbury – to address flooding concerns. Over time, the name changed, a watershed district was formed to replace the joint powers agreement, and the boundaries expanded to include Newport, St. Paul Park, Grey Cloud Twp. and Denmark Twp. South Washington Watershed District now covers 110 square miles, including 12 lakes, 120 miles of piped and natural streams, 2,400 acres of wetlands and the confluence of the Mississippi and St. Croix Rivers.
Development brings both challenges and opportunities. More rooftops, streets and parking lots means more places where rain and melting snow runs off instead of soaking into the ground. In the land-locked northern portion of the watershed, increased runoff used to cause flooding that put homes and roads underwater in southern Woodbury and northern Cottage Grove. The runoff also carries dirt, pollution and nutrients from the landscape into rivers, lakes and wetlands. As a result, some of the lakes in Woodbury began to turn green with algae during the 1990s. Less obvious was the impact to groundwater. More water running off the land means less infiltrating down into aquifers; that combined with more people washing clothes, watering lawns and flushing toilets has resulted in declining groundwater levels in some parts of the watershed. Working with the county and cities to ensure sustainable groundwater use will be a priority for the watershed district in coming years. It provided $50,000 in assistance to the city of Cottage Grove to install a system at its city hall that reuses stormwater for irrigation, and has also helped to fund similar projects at Prestwick and Eagle Valley Golf Courses.
Along with changes to the landscape, development has also brought a larger tax base and more funding to address water concerns – some of which actually began back when Cottage Grove and Woodbury were nothing but farm fields. To address flooding problems, the watershed district built a regional infiltration basin on the border between Woodbury and Cottage Grove. The basin collects runoff after spring-melt and large rainstorms and allows it to soak into the ground. The 80-acre parcel, restored to native prairie and oak savanna, is part of the South Washington Conservation Corridor – a greenway that provides critical native habitat and will eventually connect trails from Lake Elmo Park Reserve all the way to the Mississippi River south of Cottage Grove Ravine Regional Park. A combination of pipes and natural streams running south from the basin will also provide a route for water to safely reach the river in the event of a mega-storm – the kind expected to be more common in the future due to climate change. Elsewhere in the watershed, the district will be working with cities and developers to size storm ponds and pipes appropriately during development and redevelopment so that communities are better protected from the impacts of large storms.
During the next ten years, South Washington Watershed District will continue working to improve water quality in area lakes and streams. The district provides grants to homeowners to plant raingardens in their yards that reduce runoff and increase groundwater infiltration. Rules established by the district require developers to use stormwater ponds, infiltration basins (large raingardens), and other best management practices in their new developments to prevent stormwater pollution. In some places, the watershed district has worked with private landowners to retrofit existing parking lots and roadways so that less runoff makes it to nearby lakes. As a result, Armstrong Lake in Oakdale; Colby, Markgrafs, and Wilmes in Woodbury; and Ravine Lake in Cottage Grove are all improving in water quality. In rural Afton and Denmark Twp., the watershed district has also been working with landowners to reduce runoff pollution to Trout Brook, which flows through Afton State Park to the St. Croix River. These efforts will continue in the future, as the district works toward cleaner lakes and streams for fishing and recreation.