Suwannee River Water Management District

Transcription

1 Suwannee River Water Management District March 10, Agricultural Water Use Monitoring Report 9225 C.R. 49 Live Oak, FL

2 2014 Agricultural Water Use Monitoring Report Suwannee River Water Management District Governing Board George M. Cole, Ph.D. Donald Ray Curtis, Don Quincey, Jr. Kevin W. Brown Alphonas Alexander Virginia H. Johns Virginia Sanchez Guy N. Williams Gary Jones Executive Director Ann B. Shortelle, Ph. D.

3 Table of Contents Background... 1 Introduction... 2 Monitoring Methods... 8 Monitoring Status Monitoring Results Future of Agricultural Water Use Monitoring Table of Figures Figure 1. Preliminary USGS Estimated Groundwater Use in North Florida Counties: Figure Groundwater Permitted Allocation by Major Category... 3 Figure 3. Agricultural Permit Size Relative to Total Agricultural Allocation... 5 Figure 4. Irrigated Areas by Major River Basin... 6 Figure Irrigated Area by County... 7 Figure 6. Permitted Active and Proposed Groundwater Allocation by County... 7 Figure 7. Typical Datalogger, With Cover Removed Figure 8. Approximate Area Served By Electrical Cooperatives... 9 Figure 9. Typical Electric Meter Figure 10. Portable Flowmeter Attached to Irrigation System for Flow Measurement.11 Figure 11. Monitoring Types by County Figure 12. Withdrawal Points Slated for Monitoring In 2015 by County Figure 13 District-Wide Percentage of Monitored and Unmonitored Wells by Acreage Figure 14. District-Wide Percentage of Monitored and Unmonitored Wells by Allocation Figure 15. Average Withdrawals From Monitored Users As A Percentage of Their Permit Allocations Figure 16. Average Monthly Application Rate Figure 17. Average Monthly Application Rate And Rainfall,

4 List of Tables Table 1. Typical Costs For Direct And Electrically-Monitored Withdrawal Points Table 2. Irrigated Area And Status Of Wells Table 3. Allocation Of Monitored Wells... 14

5 Drip irrigation system Background Without actual use data, efforts to plan future new withdrawals or to model the effects of withdrawals on the aquifer are reliant on estimation methods. In 2013, the District Governing Board, recognizing that accurate data for planning and modeling is essential for water management, enacted a water use monitoring rule requiring monitoring of withdrawals from wells with an inside diameter of 8 or greater and on surface water withdrawals with a pipe size of 6 or greater on new permits or permits subject to renewal or modification. In anticipation of the new rule, in September 2012 the Governing Board approved a directive that provided assistance for water use reporting for agricultural users. It was the intent of the Board to offer a convenient, inexpensive, and unobtrusive alternative to self-reporting by giving permittees the option, at no charge, to have District staff collect water use data from their irrigation systems. The Board recognized that District resources could be more effectively applied to the actual collection of water use data, rather than the administration needed to enforce self-reported data, and that direct monitoring would result in high quality, impartial data. It was the further intent of the Board that the data be used only for estimation purposes in planning and modeling. In order to expand data collection beyond new permits, modifications, and renewals, the District offered a permit extension for existing users as an incentive to voluntarily enter the program. The directive was designed to work in conjunction with permit conditions to ensure automated reporting of water use data for maximum reliability and the least amount of cost. The following report summarizes agricultural water use for the first full year of implementation. 1

6 Introduction The District completed a water supply assessment (WSA) in The results of the 2010 WSA identified four water supply planning regions which were declared Water Resource Caution Areas by the District Governing Board. The 2010 WSA concluded that declining water levels are apparently the result of groundwater withdrawals originating in the District, the St. John s River Water Management District (SJRWMD), and the State of Georgia. Figure 1. Preliminary USGS Estimated Groundwater Use in North Florida Counties: 2010 Data compiled by the US Geological Survey. Total Groundwater use per county provided in Million Gallons per Day. Groundwater uses over 10 MGD are identified by user group within each county The 2010 WSA highlighted the shared groundwater resources between the District and the SJRWMD. As a result, an Interagency Agreement was executed on September 13, 2011, between the District, the SJRWMD, and the Florida Department of Environmental Protection. The main components of the Agreement include a literature review, development of a joint regional groundwater flow model, data collection and sharing, and the development of a joint regional water supply plan. The Agreement prompted initiation of the joint development of the North Florida Southeast Georgia Regional Groundwater Flow Model and the creation of the North Florida Regional Water Supply Partnership Stakeholder Advisory Committee in order to get stakeholder input during the joint regional water supply planning process. Development of a regional groundwater flow model, which is an integral part of the regional water supply planning process, requires the best data available. One of the primary calibration 2

7 inputs to the model is water use data. The collection of water use data is critical to the planning process to make the most accurate predictions possible for future water use estimates. Historically the District has collected water use data from some public supply and industrial users, but no long-term data from agricultural users. The District collected data from up to 176 agricultural withdrawal points at 48 volunteer farms between 2008 and 2012, which was the most intensive data collection attempted up to that time. By the close of 2014, permitted agricultural water use made up 36% of the total District surface water and groundwater allocation and 66% of the groundwater allocation (Figure 2). Currently the vast majority of all agricultural water use in the District is withdrawn from groundwater. Figure Groundwater Permitted Allocation by Major Category 5 MGD 32 MGD 151 MGD 369 MGD Agricultural (66 %) Commercial/Industrial/Mining (27 %) Landscape/Recreation/Aesthetic (1 %) Public Supply (6 %) Agricultural use accounted for 66% of the total groundwater allocation District Agricultural Permitting, Allocations, and Irrigated Area District rules require individual consumptive use permits for groundwater withdrawals greater than 100,000 gallons per day and wells 8 or larger, or systems of a combined capacity of 1 MGD or greater. As of the end of 2014, there were 1,673 agricultural water use permits with a total allocation of 369 million gallons per day (MGD). For perspective, the allocation is about 8% of the average annual flow of the Suwannee River near Branford. The District began using the Agricultural Field Scale Irrigation Requirements Simulation (AFSIRS) supplemental irrigation model in July 2013 for the evaluation of the water demands of new agricultural water use permits. Supplemental irrigation is the amount of water needed for a particular crop in addition to rainfall. The model was developed by the University of Florida Institute of Food and Agricultural Sciences (IFAS) and it simulates daily water balance of the 3

8 crop root zone using historic climate data (rainfall and evapotranspiration). This effect significantly improves the estimation of irrigation water needs. Model inputs include crop type(s), irrigation system type and efficiency, planting season(s), soil type(s), soil water holding capacity, water table depth, and other parameters. The District evaluates supplemental irrigation needs based on the 1-in-10 year drought conditions, which reflect below-average rainfall and above-average evapotranspiration. The assumed drought conditions mean that allocations likely over-represent the groundwater actually pumped during normal or wet years. AFSIRS predictions of agricultural supplemental irrigation water needs are more accurate than models used previously by SRWMD. The model is also used in water supply planning estimates of current and future agricultural water use demands, which will ultimately align with permitted allocations. AFSIRS is accessed through an online GIS-Based Water Resources and Agricultural Permitting and Planning System (GWRAPPS) interface. Field of young soybeans in Suwannee County 4

9 Of the nearly 1700 agricultural water use permits in the District, 55% have allocations of less than 100,000 gallons per day. The largest 5% of permits hold 39% of the agricultural water use allocation. The top 10% hold 55% of that total, while the top 50% represent 94% of the total agricultural allocation, meaning 50% (over 800 permits) account for only 6% of the allocated use (Figure 3). Figure 3. Agricultural permit size relative to total agricultural allocation Agricultural Permit Size Relative to Total Agricultural Allocation 100% 90% Percent of Total Agricultural Allocation 80% 70% 60% 50% 40% 30% 20% 10% 0% Largest Permits Smallest Permits Permits Ranked from Largest to Smallest The largest 100 permits account for over 40% of the agricultural allocation 5

10 An estimated 75% of the allocated agricultural groundwater allocation and 90% of the irrigated acreage occurs in the Suwannee River and lower Santa Fe River basins. Figure 4 shows the concentration of irrigated acreage in these basins. Figure 4. Irrigated Areas by Major River Basin Estimated 2010 Florida Statewide Agricultural Irrigation Demand (FSAID) coverage courtesy of FDACS. Waccasassa acreage includes acreage east of the basin boundary As of 2014, there were an estimated 142,000 acres with active or proposed irrigation systems. Suwannee County had by far the highest acreage with 37,839 acres. Taylor County had the lowest acreage associated with a permitted use, followed by Bradford and Union counties (Figure 5). 6

11 Figure Irrigated Area by County Alachua Bradford Columbia Dixie Gilchrist Hamilton Jefferson Lafayette Levy Madison Suwannee Taylor Union 0 5,000 10,000 15,000 20,000 25,000 30,000 35,000 40, Estimated Active and Proposed Irrigated Area (Acres) Total estimated acreage is 142,000. Source: SJRWMD, 2012 SRWMD county total irrigated acreage from Table B-1, Estimating Florida Statewide Agricultural Irrigation Demand (FSAID) using Economics and Engineering Models Report by the Balmoral Group, dated 9/22/14, with permitted data added by SRWMD. Because allocations within the District s permitting database were derived using more than one method and the allocations are considered to represent higher-than-typical usage, allocation values are not used directly in planning or modeling. However, in the absence of actual use data they are used to spatially distribute estimated actual use. Allocations by county generally follow the pattern of irrigated acreage, with Suwannee County having the highest total allocation (88.9 MGD) of permitted actual and proposed groundwater use (Figure 6). Figure 6. Permitted Active and Proposed Groundwater Allocation by County Alachua Bradford Columbia Dixie Gilchrist Hamilton Jefferson Lafayette Levy Madison Suwannee Taylor Union Allocation (MGD) 7

12 District Monitoring Program As an incentive to increase the number of monitored wells, the District offered a permit extension for water users who voluntarily sign up for the monitoring program. In addition, water users who are involved in District water-conservation cost-share programs are required to enroll in the monitoring. The directive expires in September 2017, unless extended by the Board. Monitoring Methods Direct Monitoring: Once the monitoring rule was implemented in March of 2013, District staff began deploying monitoring devices on qualifying systems. The devices use a datalogger that monitors the presence or absence of threshold pressure that indicates whether the system is pressurized or not. The units are stand-alone, with the only connection to the system being a ¼ pressure line. The monitoring units are equipped with cellular modems that transmit hourly data to the District. Cellular data costs are about 20 cents per month per unit. The Florida Department of Agriculture and Consumer Services (FDACS) provided funding for most of the units in use. Where possible, staff re-purposed equipment from the voluntary water use program. For the new program, staff chose equipment that was consistent with existing District hydrologic data collection to streamline purchasing and eliminate redundant datahandling software. Maintenance consists of cleaning solar panels and replacement of desiccant, and is scheduled for twice a year when crop types are recorded. Data is stored as both hourly and monthly run time, in hours. Figure 7 shows a typical logger/pressure sensor/modem device. Figure 7. Typical Datalogger, with Cover Removed. 8

13 Electrical Use Monitoring: Pumps that use electricity outnumber diesel-run pumps by almost two-to-one for withdrawal points that are subject to District monitoring. Staff recognized that electrical energy use could be used as a proxy for direct monitoring. Staff understood that asking water users to submit power bills or read their meters would be a formidable administrative challenge, and proposed that electrical use data be sent directly from the power companies, provided that the water users authorize the reporting. The District worked with four electrical cooperatives that provide the majority of service in the area to produce reports of electrical use for qualifying systems (Figure 8). Figure 8. Approximate Area Served by Electrical Cooperatives The first agreement was signed in November 2013, and the last in March Two other utilities declined participation. The cooperatives provide energy use reports in kilowatt-hours and peak 15-minute demand in kilowatts for each billing cycle with the permission of the account holders. Run-time in hours is computed from these reports and stored in mostly 30-day increments. The method is suitable for most of the systems that run on electricity, but is not suitable for complex, interconnected systems or ones that have highly variable flow rates. 9

14 Figure 9. Typical Electric Meter Meter information is recorded in the field and provided to the local cooperative along with a signed permission form from the electrical account holder For both methods, flow rates are either measured using an ultrasonic flow meter (Figure 10), or estimated based on irrigation system size or well capacity. Approximate costs for both methods are shown in Table 1. Table 1. Typical Costs for Direct and Electrically-Monitored Withdrawal Points Direct Electrical-Use Cost per Withdrawal Point Monitored Monitored Equipment $1, $0.00 Installation $ $0.00 Permissions and Meter Information Acquisition $0.00 $90.00 Flow Measurement (1 hour) $60.00 $60.00 Set-up Costs Total $1, $ Maintenance/Crop Entry (biannual) $80.00 $ % Equipment replacement $60.00 $0.00 Quality Assurance / Quality Control $24.00 $24.00 Data plan(annual)* $3.00 $10.00 Maintenance costs (annual) $ $54.00 *Varies Staffing for the program in 2014 consisted of one full-time hydrologic data collection specialist, one three-quarter-time Engineer 1, one quarter-time program supervisor, and help from permitting and water resources staff. 10

15 Figure 10. Portable ultrasonic flowmeter attached to irrigation system for flow measurement. Accurate measurements require several feet of straight pipe upstream and downstream of the meter. Monitoring Status As of December 31, 2014, over 200 monitoring devices were installed and 235 wells were monitored through power use (Figure 11). Around 90 of the monitoring devices were installed where electrical use estimation is applicable. Data from these devices were compared to the power use estimation, and found to be within 3-4% on systems with consistent flow rates. Monitoring devices from these sites will be moved to diesel-powered systems, although a few will be left in order to provide continued assurance that the electrical-use method is accurate. Figure 11. Monitoring Types by County 60 Number of Wells Electrically Monitored Directly Monitored Both Methods

16 Staff initially focused on larger projects, resulting in a faster rollout since the larger projects have fewer points of contact and have multiple wells that are close to each other. Fewer than 4% of the total agricultural permits have allocations greater than 1 MGD. Of these large permits, 70% have monitoring conditions with almost half being monitored. On the other end of the spectrum, 55% of agricultural permits have allocations of 0.1 MGD or less. Six percent of these small permits have monitoring conditions. More than 300 applications for new permits, renewals, and modifications were received in 2013 and 2014, resulting in a backlog of wells with monitoring conditions. Figure 12 shows the number of wells with monitoring conditions awaiting sign-up into the program. About one-third of these wells had not been drilled as of December 31, Figure 12. Withdrawal Points Slated for Monitoring in 2015 by County Wells Slated for Monitoring in 2015 by County 120 Active Wells with Monitoring Condition Proposed Wells with Monitoring Condition 100 Number of Wells Active wells have been drilled. Proposed wells have been permitted, but not drilled as of December 31,

17 By the end of 2014, 31% of the District s estimated irrigated acreage was being monitored, with an additional 25% signed up for monitoring. An additional 13 percent of qualifying total acreage was identified as associated with proposed wells that is, wells that were permitted in but were not drilled by the end of The 31% of actively monitored acreage is equal to the acreage associated with permits that do not have monitoring conditions. In the unlikely event no more wells are signed into the program and all proposed wells are drilled, when the backlog is caught up about 70% of the District s irrigated acreage will be monitored. Table 2 shows the breakdown of acreage associated with monitored wells, active and proposed wells with monitoring conditions, and wells without monitoring conditions by county. Table 2. Irrigated Area and Status of Wells By County Monitored 31% Enrolled and Drilled 25% Figure 13 District-wide percentage of monitored and unmonitored wells by acreage Not Enrolled 31% Enrolled but Not Drilled 13% 13

18 In the absence of actual use data, permitted allocations are used for spatially distributing estimated actual water use in planning and modeling. Table 3 shows the breakdown of permitted allocations associated with monitored wells, active wells with monitoring conditions, proposed wells with monitoring conditions, and wells without monitoring conditions. Slightly more than 50% of the District s agricultural allocation is currently not subject to monitoring, whereas only 31% of the acreage is not. This is likely due to a bias in the dataset, where newer permits with monitoring conditions have had allocations derived using the more conservative GWRAPPS model discussed earlier in this report. Table 3. Allocation of monitored wells Monitored 23% Enrolled and Drilled 17% Enrolled but Not Drilled 9% Figure 14. District-wide percentage of monitored and unmonitored wells by allocation. Not Enrolled 51% 14

19 Monitoring Results Overall, water use in 2014 by monitored users was 47% of their permit allocations (Figure 15). In terms of volume pumped, total monitored use was 40 MGD out of an allocation of 85 MGD. Figure 15. Average withdrawals from monitored users as a percentage of their permit allocations. Monitored Allocation 40 MGD 47% of Total Monitored Allocation 85 MGD Monthly data shows the seasonality of irrigation in the District. April, May, and June have the highest water use, based on monitored overhead systems with records beginning in On average, these three months accounted for almost 50% of the withdrawals for the year (Figure 16). Winter months, usually the time of highest aquifer recharge, had the lowest rates. Data since 2008 also shows variability across months according to rainfall patterns, although variability is also highly dependent on crop types, which include field corn, peanuts, soybeans, and carrots. While 2014 had above-average rainfall overall, the distribution was uneven, with one of the wettest winter-spring periods since the 1990s and in most areas the driest summer since the 1950s. Overhead irrigation rates in April and May of 2014, both much wetter than normal and following a wet winter, were the lowest in the 7 years of records (Figure 17). Figure 18 shows average monthly application rates and rainfall since Figure 16. Average monthly application rate, Average Application Rate Per Month Inches April Jan 2008 Jan 2009 Jan 2010 Jan 2011 Jan 2012 Jan 2013 Jan 2014 Jan 2015 May June 15

20 Figure 17. Average monthly application rate and rainfall, Wetter than normal month Drier than normal month Normal month Monthly Rainfall Rates were calculated from overhead systems over a variety of crops and crop rotations. Rainfall totals are the average of Madison, Suwannee, and Hamilton county rainfall, since most of the irrigation systems in the dataset were located in these counties. 16

21 Future of Agricultural Water Use Monitoring The program s primary goal in 2015 is to continue adding new wells into the database. Other goals include: Use data to verify existing irrigation demand models, which include statewide values that may not correspond to local soils, climate, and practice. Use data to identify relationships between water use and variations in local rainfall and soil type. Use data to provide a solid anchor for the next cycle of water use projections and in support of groundwater modeling. Investigate ways to further reduce monitoring costs. Subsurface drip irrigation for corn crop July

22 March 10, 2015 For additional information please contact Suwannee River Water Management District 9225 CR 49, Live Oak, FL