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  • 1

    South Loup Watershed Management Plan

    Open House April 5, 2016

  • 2

    Welcome

    Introductions

    Name

    Affiliation/Role

    What is your primary concern in the South Loup Watershed?

    Make sure you have signed in

  • 3

    Todays Objectives Share the results of watershed study

    Allow for 1-on-1 conversations with each agency

    Provide opportunity for public questions and input

    Please

    Provide Input

    Ask Questions

    Fill out a Comment Card

  • 4

    Project Partners

  • 5

    Consultants Assisting

    Central hub for various local, state and federal datasets

    Non-biased opinion Engineering and Scientific Resources Experienced in writing watershed plans JEO Project Manager: Adam Rupe

  • 6

    South Loup Land Use

  • 7

    E. Coli Impairment

  • 8

    Overall Project Goals

    Identify the causes of the problems

    Recommend solutions that are based on accepted and tested agricultural Best Management Practices (BMPs) or Conservation Practices

    Get input from local residents

    Compile everything into a plan

  • 9

    Project Components

    Stakeholder and Public Involvement

    Hydrology Analysis

    Identified Conjunctive Management Opportunities

    Stream Assessment

    Pollutant Source Identification

    Recommendations

    Surface Water Quantity

    Surface Water Quality

    Groundwater Quantity

    GroundwaterQuality

    Holistic Approach

  • 10

    Stakeholders & Public Involvement

    Public Survey

    Stakeholder Meetings

    Community Presentations

    News Articles

    Website Information

    Public Open House

    Land Owners | General Public | NRCS | NRDs | DNR| NDEQ| Nebraska Game & Parks

  • 11

    Watershed Survey

    May 5, 2015 Kickoff Meeting

    June 3 496 Postcards mailed out

    June 11 - Survey Press Release

    Total of 51 Responses (10%) Received

    0

    5

    10

    15

    20

    25

    30

    Responses Volume

    *Collected via Internet (hardcopy optional)

  • 12

    Survey Objectives

    1. Identity Best Management Practices (BMPs) that are currently being utilized in the watershed

    2. Identify what additional BMPs would landowners/residents be most willing to implement

    3. Identify additional steps that may be necessary to increase implementation of BMPs

  • 13

    Survey Results Summary

    Over 50% aware of groundwater and stream level declines

    Approximately 25% aware of water quality problems in river

    Some conservation practices already implemented in watershed

    Respondents are willing to implement additional BMPs costs are biggest hurdle

  • 14

    Hydrology Assessment

    Purpose:

    1. Document trends in factors that potentially impact flows in the South Loup River

    2. Determine watershed runoff volumes for use in the water quality modeling efforts

  • 15

    Trends in Annual Precipitation

    Precipitation data available at Ravenna, Broken Bow, and Arnold

    Conclusions: Mixed trends in precipitation

    gages Departure from long-term

    averages trending to be more greater

  • 16

    Trends in Measured Streamflow Incomplete gage records at Ravenna as well as

    limited dataset (5-yrs of data) at Arnold Analysis considered South Loup at St. Michael,

    Mud Creek, and South Loup above confluence with Mud Creek.

    Conclusion: Declining trend in gaged streamflow trend is less severe during 1986-2011 period

  • 17

    Well Development and Estimated Depletions

  • 18

    Hydrology Assessment Summary

    Declining trend in gaged streamflow trend is less severe during 1986-2011 period

    Little or no trend in watershed runoff for 1986-2011 period Mixed trends in precipitation gages; departure from long-

    term averages trending to be more severe Plateau in the groundwater depletions curve is

    correlated to the limitations on new well development.

    Only 21 wells installed post-2008 under LB483;corresponding to 1,455 new irrigated acres in the South Loup watershed.

    Still seeing lag effect from depletions

  • 19

    Conjunctive Management (CM)

    Coordinated and combined use of surface water and groundwater to accomplish the following, for example:

    Increase the availability and reliability of that supply.

    Reduce groundwater declines

    Protect water quality

    Fundamental recognition of hydrologic interconnection of SW and GW management decisions must consider both

  • 20

    Typical CM Components

    Storage of excess SW through recharging aquifer

    Reduction of SW/Increased Use of GW during dry periods

    Ongoing monitoring program to inform management decisions

  • 21

    Potential CM Project Locations and Criteria

    Areas completely contained within 10/50 area (hydrologically connected)

    Areas of groundwater declines

    Areas with highest bacteria loads

    Areas in the upper half of the South Loup watershed

  • 22

    Other Siting Criteria

    Excess Flow is defined as those streamflows that are in excess of the existing surface water rights that are in priority

    CENEB shows that on average: 88% of precipitation in the South Loup basin is lost to

    evapotranspiration

    8% is lost to deep percolation (groundwater recharge).

    On average only 4% of rainfall is available for capture as runoff. Comparable to approximate 3% basin yield, based on runoff trend analysis

    Detention along the main stem of the South Loup River or one of its perennial tributaries would likely be more viable than runoff alone

  • 23

    On-Stream CM Opportunities

    Capture Runoff + Baseflow during non-recreation season

    Functions: Biological/Natural treatment of bacteria

    Active storage managed to augment flows during low flow periods (quantity and quality benefits)

    Flood storage to detain/treat watershed runoff

  • 24

    Recharge and Retiming Affects

    Seepage provides return flows over entire year, including irrigation season

    Active releases increase stream levels during low flow periods

    Reduce concentration of bacteria (dilution) in River

  • 25

    On-Stream Storage Facility Elements

    Normal Pool Active bacteria treatment

    Active Storage Managed storage and releases

    to augment streamflows during low flow periods

    Target is based on deficit between average drought flows (2001-2006) and average flows (1988-2011)

    Flood Storage - volume to detain 1 of watershed runoff for 48 to 72 hours

  • 26

    ELM 10/50 Area and Potential Recharge Sites

    Perennial tributaries modeled: Sand Creek (Callaway)

    Sand Creek (Arnold)

    North Fork of South Loup River

    Spring Creek

    Conclusion: Sand Creek (Callaway) and Sand Creek (Arnold) subbasins have negligible (modeled) baseflow

  • 27

    Areas with Highest Bacteria Load

  • 28

    North Fork of South Loup River Example

    Runoff Storage: Capture first 0.5 inches of rainfall

    Drainage Area: 23 sq. mi.

    23 sq. mi. x 640 ac/mi x 0.5 inches x (1 ft/12 inch) = approx. 620 AF flood storage req.

    Active Storage Deficit in average July/August/September flows

    during drought is approximately 215 AF

    Normal Pool Active bacteria colony (assume 10AF)

    Functional Storage Volume= 620 AF + 215 AF + 10 AF = 845 AF

    Flood Storage= 845 AF x 20% = 170 AF

    Total storage = 1,015 AFApprox. Project Area = 80 acres*

    *Area estimate based on 15-ft average depth, and increased 20% for squaring land area

  • 29

    North Fork of South Loup River Example

    Conclusion Based on modeled baseflow

    estimates, the North Fork of South Loup River monthly baseflow exceeds the normal storage requirement.

    This means that the baseflow captured should make up the streamflow deficit during an average drought.

    This streamflow deficit is located at the confluence with the tributary and the South Loup River.

  • 30

    Summary Sites on perennial streams were conceptually

    developed to provide: active storage for flow augmentation detention storage for water quality benefits (dead pool for

    bacteria treatment)

    A flow monitoring program of mainstem and tributary streamflows in the upper part of the South Loup Watershed should be initiated in order to prioritize potential project locations and feasibility.

    Data from monitoring efforts can: confirm supply estimates refine augmentation goals

  • 31

    Summary Specific site locations on tributaries were not identified as

    part of this conceptual effort. Considerations for future efforts in siting projects on tributaries should include: Maximizing available water for capture Water quality hotspots, where treatment provides most

    benefit Potential environmental impacts of project infrastructure Connectivity of aquifer to streamflow at site location Potential impacts to existing infrastructure Adjacent landowner impacts both structure/pool impacts as

    well as elevated groundwater level impacts Opportunities for additional augmentation (above benchmarks

    considered in this analysis) or storage opportunities above storage requirements discussed (e.g. recreation pool)

  • 32

    Pollutants of Concern

    Pollutant Common Sources Impacts

    Bacteria (E. coli) Livestock manure Septic systems Wildlife

    Human health risks

    Nutrients

    Fe