Wilber Groundwater Quality

Implementation Plan

City of Wilber, NE

May 5, 2015 – 10:00 am

Nebraska Wellhead Protection Network

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Jason Ripa, Wilber Water Operator

Jonathan Mohr, Environmental Planner/Scientist

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Wilber WHPA

• Population – 1,855• 2,800 acres

CATEGORY 2014

Corn 1024

Sorghum ND

Soybeans 959

Winter WheatND

Alfalfa 8

Other Hay/Non Alfalfa

30

Fallow/Idle Cropland

ND

Open Water 7

Developed 224

Deciduous Forest64

Grass/Pasture

482

Woody Wetlands2

Total AcresAssessed

2,800

2003 – NDEQ’s SWP Grant

Flow meter and ET gages

Soil moisture probes

Agronomic soil sampling (0-36”)

Soil sampling reporting

UNL Extension – Saline County & Wilber/Clatonia FFA outreach

Residential water sampling and bacteria sampling

Four vadose zone samples - UNL

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Past Source Water Protection Efforts

2008 – NDEQ’s SWP Grant

Irrigation management – ET gages, education, watermark sensors

Nutrient management – educational meetings, agronomic soil sampling (0-36”)

GIS and contaminant source mapping

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Past Source Water Protection Efforts

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Municipal NO3 Trends

Data Collection

Analysis and Reporting

On-the-Ground Activities

Community Workshop

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2014 SWP Project Goals

30 sites total in 12 different fields

15-feet deep, composite samples (0-3, 3-6, etc.)

Analysis using agronomic laboratory

Sampled two native prairies to have a natural background level

Recorded tillage, fertilizer, and irrigation practices, cattle, etc.

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2014 Vadose Soil Sampling

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Root Zone & Vadose Zone

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Soil Sampling

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Soil Sampling

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Groundwater Quality Data

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Land Cover Trends

National Agricultural Statistics Service (NASS)

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Geologic Cross Section

Depth Below

Ground Surface General Soil Description

0 20 Clay with top soil

20 50 Sand mixed with gravel

50 55 Discontinuous clay layers

55 120Sand mixed with gravel

120 140Gravel mixed with sand

140 160Clay/shale/sandstone

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Geologic Cross Section

Depth Below

Ground Surface General Soil Description

0 20 Clay with top soil

20 50 Sand mixed with gravel

50 55 Discontinuous clay layers

55 120Sand mixed with gravel

120 140Gravel mixed with sand

140 160Clay/shale/sandstone

According to UNL, nitrate travels 2.5 to 3.0 feet/year

• Faster through sand/gravel than clay

• Wellhead Protection Area has a 20 foot clay layer

• Approximately 25-30 years for NO3 to travel to groundwater through 80-feet of material

• What was applied in the late-80s

or early 90s is what may be in

the aquifer now

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How long does it take NO3 to travel?

Source: Plant and Soil Sciences eLibrary, UNL

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Native Prairie Soil Results

Native Prairie = 7 lbs/acre-foot, used as a natural background

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Dryland vs. Irrigated Soil Results (Median)

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Irrigated Soil Results

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Dryland Corn Soil Results

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Field with no anhydrous, spring application

No anhydrous, spring application only

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Former CRP (cropped 2014/15)

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Overall Results Comparison

PRAIRIE VS. DRYLAND VS. IRRIGATED (MEDIAN) LBS/ACRE-FT

DEPTH PRAIRIE DRYLAND DRYLAND EXCESS

LOADING

IRRIGATED IRRIGATED EXCESS

LOADING

0-3' 5.3 21.5 16.2 28.8 23.5

3-6' 7.1 15.3 8.2 24.3 17.2

6-9' 7.1 15.0 7.9 25.8 18.7

9-12' 7.1 14.5 7.4 27.0 19.9

12-15' 7.1 12.2 5.1 19.1 12.0

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Potential Load Reduction Estimates

Land Management Scenario Estimated Reduction(lbs/ac-ft)

Conversion of Irrigated to Dryland 14.5

Conversion of Irrigated Row Crop to Grass

21.6

Conversion of Dryland Row Crop to Grass 7.4

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Irrigation Status

What is the Wilber Groundwater Quality Implementation Plan?

• 40-page Plan that discusses nitrate levels in soil, groundwater, and land use cover trends within the WHPA

• Management practices

• Monitoring recommendations

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Planning Document

How can the City Council utilize the Plan?• “Assisting with decision making for future well locations in

addition to management decisions related to the quality of groundwater in the Wilber source water area.”

• A tool in the toolbox

• Eligibility for funding through LBBNRD’s

District-wide watershed plan

• Written as an “Implementation Plan”

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Planning Document

1. Complete a detailed vulnerability assessment for the WHPA and upgradient areas one mile

2. Utilize this plan, along with LBBNRD’s District-wide Nonpoint Source Plan, to apply for additional funding

3. Work with NDEQ, LBBNRD, and UNL Extension to gather data

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Plan Recommendations

4. Establish an annual nitrate monitoring network utilizing FFA

5. Continue abandoning wells

6. Consider two more monitoring wells in addition to LBBNRD’s 2015 well

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Plan Recommendations

1. Irrigation Scheduling – reduced leaching

2. Furrow Irrigation Conversion to Pivot – reduced leaching

3. Chemigation – putting fertilizer on when the plant will use it quickly

4. Variable Rate Irrigation (VRI) – reduced leaching

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Irrigation Management Practices

Cropmetrics.com

1. Continuous No-till

2. Crop Rotation – alfalfa, wheat

3. Cover Crops – soil health, nutrient management

4. Crop to Grass Conversion

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Cropping Management Practices

1. Split Nitrogen Application – two small batches

2. Nitrogen Inhibitors – this practices is debatable

3. Spring Fertilizer Application Only

4. Record Keeping – following through with recommendations

5. Soil Sampling – producer financial benefits

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Fertilizer Management Practices

A detailed vulnerability assessment will allow the City to:

1. Better characterize the vulnerability of the aquifer to potential surface contamination,

2. Understand the horizontal and vertical extent of contaminants,

3. Verify the source water area, and;

4. Identify additional land management strategies to reduce the threat.

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Detailed Vulnerability Assessment

1. Wilber Nitrate Reduction ProgramRow crop to alfalfa conversion – $125/acre up to 100 acres

Spring fertilizer application - $15/acre up to 500 acres per year

Agronomic soil sampling – 90 samples for two years plus 400 2.5-acre grid samples

Producer workshop with featured speaker on nitrate reduction practices

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2015 Wilber SWP Planned Actions

2. EquipmentWater level measuring equipment

Dedicated level logger and pump (additional monitoring well installed by Lower Big Blue NRD)

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2015 Wilber SWP Planned Actions

Provided by LBNRD

3. Groundwater Quality Data CollectionWell sampling and analysis – sample up to 30 wells 3x in 2 years

Nitrate and bacteria (one round)

Record well screening intervals

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2015 Wilber SWP Planned Actions

Provided by LBNRD

4. Detailed Vulnerability AssessmentHydrogeological cross sections

Evaluating nitrate data, screened intervals and well depths of 30 wells to be sampled

Review well logs and construction data on municipal wells

Create aquifer vulnerability map based on material and thickness of source aquifer

Review existing WHPA model

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2015 Wilber SWP Planned Actions

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Detailed Vulnerability Assessment

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Detailed Vulnerability Assessment

1. Nitrate levels in Nebraska will continue to rise as irrigation is expanded

2. Water quality data was outdated, to make sound decisions data collection is vital

3. Producers are changing their methods, but incentives are necessary

4. Soil sampling – biggest bang for the buck, used as a ‘non-financial incentive’

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Take Home Messages

5. Planning allowed City to layout priorities for several years

6. Soil nitrate data allowed to make a scientifically informed decision for a long-term high-quality water supply

7. Soil sampling and other activities have caught the attention of the producers

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Take Home Messages

Questions?

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