In this issue: Shell Creek Watershed improvement plans, AFO rules, aquifer mapping via helicopter, Lake Wanahoo, and more
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Innovative Bio-Engineering Approaches for Shell Creek

Facing ongoing challenges with erosion, water quality and flooding, the Shell Creek Watershed Improvement Group (SCWIG) is looking at some innovative approaches to improving the health of this watershed in northeast Nebraska. 

SCWIG, a group of landowners and farmers that formed in 1999, has seen considerable success in promoting no-till, buffer strips and other Best Management Practices to help improve the quality of the water draining into Shell Creek. Now, the group is ready to tackle some of the major structural issues with the creek itself.

The Shell Creek Watershed Environmental Enhancement Plan was completed earlier this fall and recommends three kinds of structural improvements to the creek: 

“Log cribwall stabilization” is being recommended to help reduce bank erosion. This is  a bioengineering alternative to the traditional rip-rap method and involves placing stacked layers of logs, rocks, and soil along the edges of a creek.

“Bench wetland restoration” is being recommended to reduce further cutting of the creek channel and to provide an outlet for confined floodwaters. This would involve reconnecting orphaned oxbows to the creek by excavating them down to the current flood level.

Tributary stabilization is the third structural measure being recommended. Along the lower reaches of many of Shell Creek’s tributaries, “knickpoints” have formed - areas where mini-waterfalls have resulted from the tributaries trying to cut their way down to the main creek’s level. Grade-control structures could help stabilize these knickpoints, reduce erosion rates, and prevent further downcutting in the tributaries.

An Open House was held in Platte Center in September 2014 to update landowners, farmers, and city and county officials on the Environmental Enhancement Plan.

To move forward with restoration plans, SCWIG is pursuing grant funds from several partners this fall, including the Nebraska Department of Environmental Quality, the Nebraska Environmental Trust, and the Lower Platte North NRD. If approved, design and permit work could begin as early as April 2015, with construction beginning the following year. Specific project locations have not yet been determined, but will likely focus on bridges, roads, and other important infrastructure. The project partners are encouraging property owners to assist with project siting and plan implementation.

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Lake Wanahoo & Facts About Flooding

On two separate occasions in early September, lowland flooding occurred in some eastern parts of Wahoo, and Highway 77 north of town was briefly closed or restricted to one lane. The NRD has received numerous questions about why this flooding wasn’t prevented by Lake Wanahoo. There are several key facts to consider: 

1. No Dam Can Provide 100% Flood Protection

Lake Wanahoo is designed to provide flood control for Sand Creek, but it was never intended to prevent all flooding under any cirumstances. Heavy rainfall events can still cause flooding, especially when other nearby creeks are running higher than usual. A good question to keep in mind is “how much worse would the flooding have been without Lake Wanahoo?”

In the five years since the dam was completed, Highway 77 has been partially or completely overtopped along a small stretch near Sand Creek a total of 3 times (2 of them this September). By way of comparison, it was not at all uncommon for Highway 77 to be completely closed and under several feet of water 2-3 times each year before the dam was built. 

2. A Dam Can Only Control Its Own Watershed

In the 10 days leading up to the flooding on September 4, the Sand Creek watershed upstream of Lake Wanahoo received 6-7” of rain (average preciptation for Wahoo is 3.5” for the entire month of September). The lake worked as intended, capturing this water and metering it out as slowly as possible. 

However, the watersheds west of Wahoo (Cottonwood Creek and Wahoo Creek), which Lake Wanahoo does not control, received 8-10” of rain over the same period. (On August 29th, a Wahoo Creek stream gage near Ithaca saw the 9th highest “peak discharge” recorded since it began operation in 1950. )

Flooding began when that water from Wahoo and Cottonwood Creeks reached the point where Wahoo Creek and Sand Creek merge south of Wahoo. With nowhere else to go, water began to back up in Sand Creek as well, eventually causing it to spill out of its banks east of Wahoo. This wasn’t a failure of Lake Wanahoo; in fact, if the dam hadn’t been controlling the rate of discharge from Sand Creek, the flooding would have been much worse.

3. Dams Are Designed for a Specific Water Level

During late spring/early summer, Lake Wanahoo is temporarily drawn down one foot below its normal level to provide extra capacity during the period of peak rainfall for the year. So, why not keep the lake at that level all the time? Because dams in climates like ours are designed to operate at full pool, with water being released constantly. Keeping the lake below that level for too long is harmful to aquatic life, water quality, recreation, and the overall effectiveness of the dam.

Look, Up in the Sky!

High-Tech Helicopter Flights to Help Map Aquifers

This fall, residents of the Lower Platte North NRD may see an unusual sight in the skies: a low-flying helicopter towing a large hexagonal frame.

No need to panic, though: this unique equipment is simply part of a project to map groundwater aquifers and subsurface geology in the district.

The NRD is a member of the “Eastern Nebraska Water Resources Assessment” (ENWRA) project, which is trying to build a precise and detailed catalog of surface and subsurface water in this part of the state. The “SkyTEM” system you may see flying this fall is part of that effort.
 

Graphic courtesy of Scott Beachler/NET Television

SkyTEM uses electromagnetic waves to remotely map subsurface geology. Here’s how it works: 

The frame that hangs below the helicopter contains a loop of copper wire that essentially turns it into a large transmitter. The helicopter flies along a predetermined grid at 50 miles per hour, with the SkyTEM apparatus transmitting rapid bursts of electromagnetic waves into the ground.

Different kinds of materials (such as the sand, gravel or clays in aquifers) respond differently to this electromagnetic stimulation. The SkyTEM equipment can detect these variations and, with computer-aided mapping tools, build detailed, 3-D maps of aquifers and other subsurface features. These maps are then cross-referenced, or “ground truthed,” with known test holes and wells.

The advantage of this system is that it can provide a much more detailed and accurate picture of aquifers, and in a much shorter time frame, than the traditional method of just drilling test holes on a grid. 

The SkyTEM flights will be taking place at various locations in the district throughout the fall and will map a total of 207 miles.

The electromagnetic waves from the SkyTEM are similar to ordinary radio waves and pose no threat to people or animals, so residents don’t need to worry if they see the mapping helicopter overhead. 

You can learn more about the project and see a video of the SkyTEM in action here. If you have any questions, please contact Water Resources Manager Larry Angle at 402.443.4675 or langle@lpnnrd.org.

Lower Platte North Multi-Jurisdiction Hazard Mitigation Plan Update

In January 2014 the Lower Platte North NRD began the process of updating the regional Hazard Mitigation Plan originally developed and approved in 2010. Communities are encouraged by FEMA to have pre-disaster mitigation plans in an effort to reduce impacts and cost associated with natural disasters. FEMA requires that these plans be updated and approved on a five year cycle. 

Communities across the NRD met in January and February to initiate the planning process. Since that time, JEO Consulting Group, Inc. has worked to gather regional data and complete the risk assessment for participating jurisdictions.

This project is funded by a grant from the Federal Emergency Management Agency (FEMA) with the local match being provided by the Lower Platte North NRD. Public meetings have been scheduled for the following dates and locations:

  • October 9th: 2:00 pm at the Fremont City Offices, 400 E. Military Avenue;
  • October 14th: 7:00 pm at the David City Library, 399 N. 5th Street; and
  • October 16th: 7:00 pm at the Lower Platte North NRD office, 511 Commercial Rd.

Community members interested in attending meetings are welcome, if you are unable to attend one of the public meetings but would like to offer insight or comment please contact your county emergency manager or the NRD. The Lower Platte North Multi-Jurisdiction All-Hazard Mitigation Plan will be posted for public review and comment upon completion on the NRD website and the project website (www.jeo.com/hazards). 

For more information on this planning effort, contact Tom Mountford, Lower Platte North NRD Assistant Manager, at 402.443.4675 or tmountford@lpnnrd.org.

 

Work on Highway 77 Expressway Reaches Wanahoo Dam

In mid-September the former County Road M running over the Lake Wanahoo dam closed for paving of the Highway 77 Expressway. 

The road will be closed between County Road 17 and the Highway 77/92/109 junction for approximately a month and a half. To access Wanahoo, use County Road 17 from the north or the east side entrance on Highway 109.

Work is expected to be complete in late October or early November. When complete, the Highway 77 Expressway will loop around the west and north side of Wahoo, run across the Wanahoo dam, and link up with the existing Highway 77/92/109 junction 1 mile north of Wahoo.

Reminder: Fall Fertilizer Restrictions


Under the NRD's Ground Water Management Areas rules & regulations, fall application of commercial nitrogen fertilizer is restricted for the entire district:
  • Fall application of commercial nitrogen fertilizer is prohibited on non-sandy soils before November 1
  • Fall and winter application of commercial nitrogen fertilizer is prohibited on sandy soils until March 1
In the district's Phase II areas (Bellwood & Schuyler/Richland areas), additional requirements apply:
  • Commercial nitrogen fertilizer only permitted on non-sandy soils from Nov. 1 to March 1 if approved inhibitor is used at recommended rates.
  • Operators applying commercial fertilizer from Nov. 1 to March 1 must furnish records from their dealer that an approved inhibitor was used as recommended.
  • Use of fertilizer calibration meters will be encouraged for all fertilizer applications.
Failure to observe fall fertilizer restrictions could lead to a cease-and-desist order from the NRD board and loss of NRD cost-share funds.
 

Questions & Answers About Animal Feeding Operations & Inspections

If you are an animal producer, you may need to request an initial inspection from the Nebraska Department of Environmental Quality (NDEQ) to determine if a Livestock Waste Control Facility is needed at your operation. Some questions that every animal producer should ask:

  • Is my operation an Animal Feeding Operation (AFO)? If so, what size category?
  • Do I need to request an initial inspection from NDEQ?
Find out how to get the answers to these questions here!

Schuyler Levee Project Nears Completion

Approximately 65% of 2.5 Mile Levee Done; Completion Projected for Mid-November

Construction is nearly complete on a levee project to reduce flooding in the city of Schuyler.

The Lower Platte North NRD and  Schuyler are the local partners in the project, which involves a 21/2 mile levee along a stretch near Shell Creek north and east of Schuyler. The Federal sponsor is the U.S. Army Corps of Engineers. 

When complete, the levee will remove approximately 20% of the city from the 100-year flood plain.

Major construction on the levee began this spring and was approximately 2/3rds complete at the end of August. Wet weather has slowed down work, but the project is still on track for completion in mid-November.

Project construction and land rights costs for the project are approximately $3.9 million, with 65% ($2.54 million) coming from the Corps and the remainder ($1.37 million) from the local partners.

Approved Flow Meters for Special Quantity Areas

Approved Flow Meters for Special Quantity Areas

Beginning in 2015, irrigators in the NRD’s Special Quantity Subareas will be required to install flow meters. Meters must be on the NRD approved list or meet all NRD specifications. Approved meters include the following:

Manufacturer: McCrometer
Model: McPropeller
Notes: all propeller meters

Manufacturer: Sparling
Model: Propeller Saddle Meter
Notes: Model 312 propeller meter

Manufacturer: ARAD Group
Model: Saddle Water Meter
Notes: meter for irrigation applications

Manufacturer: Geyser
Model: Saddle Meter
Notes: all propeller models for farmland

Manufacturer: Senniger
Model: Ag Rotor Meter
Notes: propeller model

For a full list of flow meter requirements and specifications, visit lpnnrd.org, or contact Russell Oaklund at 402.443.4675 or roaklund@lpnnrd.org.

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