First project of the season is complete

This rock channel was built to address erosion issues near Pioneer Lake.
Photo supplied

Construction season is officially underway at the Chisago Soil and Water Conservation District and the first project wrapped up in April. The project is located in Center City in a residential neighborhood. Runoff gathered in the roadside ditches and then ran into Pioneer Lake. Erosion was occurring in the channel near the lake and there was no treatment of the water before it entered the lake, bringing chemicals, fertilizers, and pesticides with it.
To stabilize the erosion, an existing rock channel was re-constructed to remove sediment that had built up over time and to shape the channel better. A properly shaped channel should have a lower middle than either side, but we often see channels where the rock is highest in the middle. This ends up pushing the water out and it runs alongside the channel where it can actually cause more problems. A bowl of rock at the bottom of the channel was installed to dissipate any remaining energy and allow sediment to drop out before the water slowly enters the lake.
Upstream from the rock channel, several of the ditch bottoms were used as pretreatment areas to help clarify the water before it reaches the rock channel. Giving water a place to slow down and temporarily pond helps sediment settle out of the water column. It also give the water time to infiltrate into the ground, where it enters the water table. Soil is a natural clarifier of water, so any water that infiltrates is cleaned. Plants take up some of the water that is able to infiltrate as well.
The pretreatment areas alone are able to remove over 280 pounds of sediment and 1 pound of phosphorus from the runoff water that would otherwise enter the lake. In the lake, a pound of phosphorus is enough to create 500 pounds of algae.
Up next: we have several agricultural projects scheduled to begin when the rain stops! Stay tuned to future updates or visit our website at www.chisagoswcd.org to see any of the projects that have been completed in previous years.

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