Infrastructure Success on Salt Creek

Infrastructure Success on Salt Creek

Nebraska’s recent floods devastated the areas around the Missouri, the Platte, and Nebraska’s other major rivers. Lincoln, the state capital, however, emerged relatively unscathed. Part of the reason for this was the successful performance of the flood control structures on the Salt Creek. These structures are operated by the Lower Platte South Natural Resources District (NRD).

In this interview, Paul Zillig, general manager of the Lower Platte South NRD, speaks with Municipal Water Leader Managing Editor Joshua Dill about the district’s experiences during the flood event and its lessons learned.

Joshua Dill: Please tell us about your background and how you came to be in your current position.

Paul Zillig: I been working for the Lower Platte South NRD for 40 years. I went to the University of Nebraska, where I majored in natural resources and agricultural economics. When I started here in 1979, the NRD had a staff of about six people. Since then, I’ve been involved in pretty much every aspect of what the NRD does. I served as assistant manager for 34 years and the last 3 years as general manager.

Joshua Dill: Would you tell us about the history of the Lower Platte South NRD?

Paul Zillig: Nebraska’s NRDs started in 1972, when the Nebraska Legislature decided to consolidate the 180 existing special purpose districts around the state into the current 23 NRDs. The state gave the NRDs a dozen statutory responsibilities and authority on pretty much all aspects of natural resources management, including flood control, groundwater management, erosion control, water supply, drainage and stream stability, recreation, forestry, and fish and wildlife habitat. It also gave them the authority to levy a property tax. The state required that each NRD had a locally elected board of directors to set priorities, hire staff, and make local decisions concerning the budget, the tax levy, and projects and programs.

Joshua Dill: How big is your service area?

Paul Zillig: Our NRD covers 1 million acres, so we’re one of the smaller NRDs in the state. We cover parts of six different counties, including the city of Lincoln. NRD boundaries closely follow watershed boundaries, so we include the Salt Creek and Weeping Water watersheds along with a few other smaller watersheds along the lower Platte River. The population of our NRD was 314,000 as of the last census, but today it is probably closer to 350,000, with Lincoln’s population nearing 300,000.

Stevens Creek A17-1, located 4 miles east of Lincoln, is one of the 180 flood control dams owned and operated by the Lower Platte South NRD.

PHOTO COURTESY OF LOWER PLATTE SOUTH NRD.

Joshua Dill: Please tell us about your experience during the recent flood.

Paul Zillig: It happened in mid-March, but it felt like the middle of winter owing to the amount of snow around. It was a surprise flood; we were anticipating nothing more than the usual localized flooding caused by ice jams along the Platte River as the spring melt occurs. We had 3/4 to 11/2 inches of rain. Typically, that type of rain event does not cause any kind of flooding problems or concerns. We were quite surprised at the amount of runoff. We monitored our flood warning system of U.S. Geological Survey stream gauges and both the U.S. Army Corps of Engineers’ and the NRD’s flood control dams. Salt Creek reached flood stage, but only caused minor damage. It was at its sixth-highest level in the past 50 years. Without the Salt Creek levees in Lincoln, the 10 Army Corps dams (the largest dam, Branched Oak, was at a record level), and all the smaller NRD flood control structures, the flooding along Salt Creek would have been much worse! We did not fare nearly as well along the Platte and Missouri Rivers.

The multi-NRD Western Sarpy Clear Creek Levee Project performed well until the flood flows exceeded the 50-year design capacity. At that point, the levees overtopped and breached at a few locations. This was a common occurrence along the Platte and Missouri Rivers in eastern Nebraska. Flood damage was widespread, and water supply services for our largest communities, Lincoln and Plattsmouth, were disrupted.

Joshua Dill: How did this flood compare to previous floods?

Paul Zillig: The flooding along the Platte and Missouri Rivers in this NRD was at all-time record levels. We hope not to see that again anytime soon! The flooding along Salt Creek was minimal: Flood elevations in Lincoln were approximately 8 feet below the record flood of 2015.

Joshua Dill: What kind of damage to your district sustain?

Paul Zillig: The main damage was to bridges and infrastructure along both the Platte and Missouri Rivers. Agricultural land was flooded and damaged by erosion and debris, but crop damage was minimal. Sand and gravel operations along the Platte River sustained some damage and have been out of operation. Local roads sustained damage. Homes, cabins, and businesses along the floodplain sustained damage, and several were destroyed. A number of bridges, railroad lines, and levees were damaged. The City of Lincoln’s well field is in the floodplain area along the Platte River that was also affected. The City of Plattsmouth experienced quite a bit of damage to its sewage treatment plant, and its wells will be not operational for most of this year; it has an agreement to purchase some water from a local rural water district.

Joshua Dill: How did your district’s flood control infrastructure perform?

Paul Zillig: The NRD’s infrastructure performed really well. The NRD owns and operates approximately 180 small dams on mostly intermittent streams. We have 13 miles of levees along Salt Creek. The Salt Creek Levee Project is an Army Corps project that the NRD now owns and operates. The Army Corps also has 10 flood control structures in the Salt Creek watershed. The largest of those structures, Branched Oak Lake, a reservoir of a little less than 2,000 acres that was built in the 1960s, was at an alltime high. It was storing 41/2 feet of additional floodwater (8,190 acre-feet of water, or 2.7 billion gallons) that otherwise would have caused more flooding downstream. Both the levees and the flood control structures functioned really well. There’s no doubt that the damage would have been a lot worse without those projects in place.

Paul Zillig.

PHOTO COURTESY OF LOWER PLATTE SOUTH NRD.

Joshua Dill: What are your top lessons learned from this experience?

Paul Zillig: The top lesson learned was that we need to keep in mind the amount of potential runoff that existing snow and ice can present. Before this flood occurred, 3/4 inch of rain wouldn’t have concerned me, but with the frozen ground and the snow and ice already on the ground, there was an additional 2–3 inches of runoff in the watershed just waiting to happen. We are accustomed to a gradual melting of snow and ice, but in this case the rain caused a rapid melt that resulted in the widespread flooding. We’re fortunate that we didn’t have even more rain, like many other NRDs did.

Joshua Dill: What are your top issues going forward?

Paul Zillig: The main challenge for the Lower Platte South NRD is aging infrastructure. We have 180 dams and 13 miles of levees. We need to make sure we continue to monitor and inspect those projects and determine when the pipes, culverts, and other facilities need to be repaired or replaced. We are also partnering with the Army Corps on a $25 million flood control project here in the city of Lincoln, the Deadman’s Run Flood Reduction Project. It’s basically a conveyance channel/bridge enlargement project. There are about 500 homes in the 100-year flood plain, so the potential flood damages and flood insurance costs are sizable. We hope to implement this project in the next 3 years. The City of Lincoln and the NRD are sharing the local costs.

We’re also partnering with the City of Lincoln to look at a flood resiliency study for the Salt Creek floodplain area. We are looking at the successes of other communities and at best management practices. We are also looking at climate change and what we can anticipate in the future and trying to figure out the steps we can take to reduce the threat of flooding.

The Lower Platte South NRD operates and maintains the 13.5-mile Salt Creek Levee Project in Lincoln, seen here during the flood of May 2015. The $22 million project has reduced flood damages by $99 million since its completion in the 1960s.

PHOTO COURTESY OF LOWER PLATTE SOUTH NRD.

In addition to flooding, another issue is drought. Three local NRDs have partnered with the Cities of Lincoln and Omaha and the state to prepare a drought contingency plan with the assistance of the Bureau of Reclamation. We know that both droughts and floods will occur again.

Joshua Dill: What has been your experience working with the Nebraska Legislature and the governor?

Paul Zillig: We have a good working relationship with the legislature and the governor. The districts of 13 of Nebraska’s 49 state senators overlap at least to some degree with this NRD. We reach out to them annually to offer to meet and discuss natural resources, any of the NRD projects or programs, or any concerns or needs in their district.

Joshua Dill: As a district whose infrastructure performed quite successfully in this flood, do you have any advice for other NRDs?

Paul Zillig: My advice is to continue to properly maintain your flood control projects. Overall, our flood control projects operated as designed. There were instances where the flows exceeded the projects’ design capacities and damaged them.

Joshua Dill: What is your vision for the future?

Paul Zillig: We really want to protect our natural resources for future generations. As I look at it as the general manager of the NRD, we really need to look closely at what we can do to minimize flood damage. There are different ways of approaching that, including projects and better floodplain management.

Our district is also looking at improving the quality both of groundwater and surface water. It is already good, but it can be better. A lot of what we do besides flood control is trying to work with landowners on helping them manage their land to improve their surface water, the runoff from their land, and the groundwater beneath their property.

Paul Zillig is general manager of the Lower Platte South NRD. He can be contacted at pzillig@lpsnrd.org.