Ernie Aust was one of the most unique NRCS employees I have had the privilege of working with. Ernie was special. He served as Area Conservationist in Southwest Iowa and I was fortunate to have him as a supervisor. Looking back, it is obvious Ernie missed his calling. His talents would have been better utilized as an engineer or resource conservationist. During our professional visits, Ernie had little interest in talking about performance appraisals and workload analysis; instead he wanted to talk about engineering practices and variations that could achieve better conservation. He loved to debate how a practice design could be modified so as to enhance resource management.
One day early in our relationship, Ernie and I had a particularly intense discussion about the form and function of a grassed waterway. As a young pup with the Soil Conservation Service (later renamed the Natural Resources Conservation Service), I was taught a grassed waterway should be designed so that any sediment carried within the water should be deposited somewhere downhill, beyond the field boarder; somewhere like the neighbor’s field or maybe even a stream or river.
The rationale for moving the sediment beyond the waterway was, and still is, to prevent excessive sediment from being deposit within the grassed waterway. This sediment causes the waterway to lose shape, reducing its capacity to carry water, which results in a need to spend money to re-shape the waterway. Well that was conventional wisdom, not Ernie Aust wisdom.
For Ernie, grassed waterways could provide more than just soil erosion benefits – they could also be designed to filter sediment from the water flowing through it. Ernie argued that grassed waterways could be designed to trap sediment, rather than passing the sediment downstream. As I later came to realize, this slight design modification was brilliant.
By design, a grassed waterway is used to reduce ephemeral erosion (Figure 1). Waterways are usually designed to be a broad and shallow vegetated channel with the purpose of moving surface water downslope across farmland without causing ephemeral erosion. Then, as water travels down the waterway, the design and vegetation prevents ephemeral erosion that would otherwise result from concentrated flows.
By Ernie’s calculations, a carefully designed waterway could probably trap a higher percentage of sediment, per linear foot, than a traditional filter strip along a stream. He argued that in order for waterways to trap sediment, they would need to be built wider and shallower, and allowed to develop dense standing vegetation (meaning, do not mow the grass). This would slow the water even more, allowing most of the sediment to drop out.
Ernie’s argument for designing sediment-trapping waterways is even more compelling to me today. What is preventing us from designing grassed waterways to trap sediment? Yes, they would need to be cleaned out and reshaped more frequently, but at least this type of system would trap the sediment closer to the source. To me, this is brilliant conservation!
That day with Ernie was an eye opener for me, but it was just another regular day for him. He was always willing to challenge traditional processes and his rationale was logical and well thought out. I had been trained by conventional resource conservationists and I was no match for Ernie’s relentless “what if” approach. Ernie was a pioneer in precision conservation, always questioning and never accepting status quo. The conservation world needs more transformative individuals like Ernie Aust. I miss working with him.