Greenspace: 2018 a watershed year for Dobbins Creek
2018 was a watershed year for water quality and flood mitigation in the Cedar River Watershed’s Dobbins Creek area.
The year wrapped up with the completion of five projects in December that slow and treat stormwater runoff from more than 1,000 acres. The projects include water-detention structures and earthen berms and restores some habitat.
However, much more is to come in 2019 as the Cedar River Watershed District is just beginning to tackle an ambitious list of 25 projects, with a total price tag of $8.4 million, to address flooding and improve water quality. So far, nine of those projects are complete with six more slated for completion in 2019. The goal is to reduce flooding by 8 percent at the Cedar-Dobbins confluence in southeast Austin.
The biggest improvement completed in 2018 was Dobbins 1. Taking years of planning and study, the Dobbins 1 project encompassed 810 acres and created a stormwater capacity covering more than 50 acres. That project allows more land to be covered with stormwater than Austin’s 40-acre East Side Lake, a reservoir created by a dam on Dobbins Creek.
“Lots of work went into it, and we were fortunate to work with great landowners,” said Cody Fox, Cedar River Watershed District project manager.
Dobbins 1 will reduce peak stormwater flows by more than 80 percent. The berms are expected to keep an estimated 134 tons of sediment and 218 pounds of phosphorus — equal to more than 65,000 pounds of algae — out of Dobbins Creek.
The projects have been funded by a $3.2 million grant from the Hormel Foundation and more than $4 million in state grants and bonds. Up to $1 million from a CRWD local project levy is available, if needed.
The 2019 projects will focus on an additional 1,000 acres. Those capital improvement projects will focus on upland water storage and slowing stormwater flow to help reduce downstream stream bank erosion.
“By slowing stormwater, these CIP structures keep a lot of soil and nutrients from entering streams while reducing flood damage to buildings, roads, bridges and farm fields,” Fox said.
Other projects completed this year include a grass waterway earthen berm north of Interstate 90 to reduce gully erosion and reduce the risk of heavy rain over-topping Mower County Road 20 downstream.
West of Dexter, an earthen berm was built to protect a downstream grass waterway by better directing rain water into it. Prior to the work, heavy rains often led to water cutting through several areas of a fence line bypassing the grass waterway, causing erosion. Another berm west of Dexter along fence lines was built to minimize obstructions in the farm field and reduce the amount of cropland taken out of production.