AGENDA ITEM D6. Climate Outlook

Transcription

1 AGENDA ITEM D6 DATE: June 1, 2016 TO: Matt Jordan, General Manager FROM: Alison Adams, Chief Technical Officer SUBJECT: Regional Water Supplies and Member Demands Status Report SUMMARY: RECOMMENDATION: This item provides the current water supply conditions, including hydrologic conditions, water demands, and sources of supply. Revisions to the Agency s Water Shortage Mitigation Plan are underway. A technical advisory committee was formed and has held two meetings. Receive Status Report DISCUSSION: Since the beginning of the fiscal year (October 2015), Tampa Bay Water has delivered million gallons per day (mgd) to meet the members demands. This is 2.33 mgd (1.47%) more water delivered than for the same period last year. The region is experiencing typical spring dry weather which has increased water demands for April and May. Daily river flows remain at seasonal lows. Storage from the regional reservoir is providing source water for the Regional Surface Water Treatment Plant. A summary of conditions is highlighted below. Total rainfall across Tampa Bay Water s service area was 2.2 inches and 3.9 inches, respectively, for the months of April 2016 and May Monthly flows in Alafia and Hillsborough Rivers averaged 127 mgd and 94 mgd (54 th and 60 nd percentile), respectively, for April. Monthly flows averaged 96 mgd and mgd (76.6 th and 34.6 th percentile), respectively, for the month of May. Reservoir storage is at 12.2 billion gallons. Desalination facility is currently online at 12 mgd and expected to be offline in about two weeks. The 12-month running average Consolidated Wellfield pumpage is at 78.9 million gallons per day (mgd). Delivery of water to Member Governments year to date (through May 2016) is 2.33 mgd higher than the same time period last year. The City of Tampa Hillsborough Reservoir is at ft. Climate Outlook Climatic conditions are continuing to transition from El Niño to La Niña. The NOAA s Climate Prediction Center indicates that La Niña is favored to develop during summer 2016, with about a 75% chance of La Niña continuing through the fall and winter

2 Matt Jordan June 1, 2016 Page 2 In addition, NOAA s Climate Prediction Center states that the 2016 Atlantic hurricane season, which runs from June 1 through November 30, will most likely be near-normal, but forecast uncertainty in the climate signals that influence the formation of Atlantic storms make predicting this season particularly difficult. This is a more challenging hurricane season outlook than most because it s difficult to determine whether there will be reinforcing or competing climate influences on tropical storm development, said Gerry Bell, Ph.D., lead seasonal hurricane forecaster with NOAA s Climate Prediction Center. "However, a near-normal prediction for this season suggests we could see more hurricane activity than we ve seen in the last three years, which were below normal. Hydrologic Conditions Water Year 2016 (October 2015 through September 2016) started with slightly below average rainfall for October, but returned to normal rainfall totals for the month of November. Rainfall totals dropped significantly in December The effects of El Niño finally arrived in January 2016 resulting in a monthly rainfall total that was twice the longterm average. Rainfall totals for February through April were slightly below normal; while rainfall totals for May was 1.4 inches above average. Year to date rainfall totals across the region are near normal, inches (only 0.01 inch less compared to long-term normal) (Figure 1). Overall, hydrologic conditions for the Tampa Bay area continue to be near normal compared to the past few years, when hydrologic conditions were wetter than normal. According to recent long-range atmospheric forecasts, hydrologic conditions may change to a drier pattern in the upcoming fall and winter as conditions transition to La Niña towards the end of Winter Permitted available flows in the Alafia River averaged mgd for the month of April and 9.68 mgd for the month of May. In the month of April, daily withdrawal of water from the Tampa Bypass Canal averaged mgd whereas withdrawal for the month of May averaged 9.22 mgd. Currently, there are no permitted withdrawals from the Alafia River or Hillsborough River as daily flows are at their seasonal lows. The City of Tampa has activated Harney Canal augmentation and has been diverting 20 mgd to supplement the Hillsborough Reservoir. Water Demand and Supply Summary For Water Year 2016, Tampa Bay Water has budgeted to deliver 164 mgd. This includes an annual delivery to the City of Tampa of 6.0 mgd average. Total delivery to the member governments for the months of April and May were mgd and mgd, respectively. These monthly water delivers are higher than spring time delivers in previous years. Total delivery for April 2016 was 1.34% higher than April 2015 delivery, delivery for May 2016 was 1.17% higher than the same month last year. Tampa Bay Water s delivery for

3 Matt Jordan June 1, 2016 Page 3 October 2015 through May 2016 averages mgd which is 2.33 mgd or 1.47% above delivery for the same period last year (Figure 2). Aggregate groundwater production from the 13 Tampa Bay Water wellfields totaled mgd and mgd for the months of April and May, respectively. Production from the 11 Consolidated Wellfields totaled mgd and mgd for the months of April and May, respectively. The 12-month running average Consolidated Wellfield production stands at 78.9 mgd through May 31 st. (Figure 3). Surface water (including water purchased from the City of Tampa) totaled mgd and mgd for the months of April and May, respectively. The Tampa Bay Water Desalination facility is currently producing 12 mgd but is expected to go offline in about two weeks. In April, a drawdown scheduled was prepared to use about 5 billion gallons of water from the regional reservoir. This planned drawdown is to allow for additional inspections of the interior surface of the reservoir and additional data collection. The plan includes lowering the reservoir stage to an elevation of 120 feet; full is a stage of feet. This level is expected to be reached in early July and refill will start soon after the inspection is completed. Refill is expected to start by mid-july. The reservoir is planned to be completely refilled by the end of September or sooner depending on summer rains. (Figure 4) For the months of April and May a total of 2.74 billion gallons of storage has been used from the regional reservoir to meet Surface Water Treatment Plan production needs. Currently BG water is stored in the regional reservoir. Water Shortage Mitigation Plan The Board approved the updated Water Shortage Mitigation Plan in February The Water Shortage Mitigation Plan uses rainfall, streamflows, and reservoir storage as indicators of the health of the region s water supplies. Tampa Bay Water is currently under normal hydrologic conditions. The outlook for the region s water supply conditions remains good. The cumulative rainfall in the region is now at 8.66 inches surplus for the month of May (compared to 9.00 inches surplus in April 2016). Stream flow is 24.4 mgd surplus for the month of May (same as for the month of April). The regional reservoir is at BG on May 31 st. Currently, the region is in transition from seasonally dry spring months to the rainy summer season. Updated climatic outlook indicates the transition of El Niño climatic condition to neutral over the upcoming summer. While the models indicate a better than 50% chance of transitioning to La Niña in winter of 2016 (close to 60% for the winter months of December-February season), it remains highly uncertain as to the strength of La Niña. Conditions will become clearer in the next two to three months. Water year 2016

4 Matt Jordan June 1, 2016 Page 4 summary and climatic outlook update for water 2017 (October 2016 through September 2017) will be presented at October Board meeting. Staff are currently updating the current Water Shortage Mitigation Plan including the triggers for entering and exiting water shortage phases. A technical working group comprised of Member Government and SWFWMD staff has been formed and monthly meetings to discuss the results of data analysis and development of the updated Plan are scheduled. The updated Water Shortage Mitigation Plan is expected to be completed by April Staff continues to work with Member Governments in collecting water restriction and conservation information, discussing and exploring various short-term and long-term demand management alternatives, implementing a consistent public awareness campaign throughout the region, and identifying additional opportunities to optimize existing water resources. BACKGROUND: Data collection, analysis, and interpretation as well as decision-making are ongoing for a multitude of factors that influence and constrain the Agency s operations. These include hydrologic and environmental conditions, supply and demand conditions, treatment plant parameters, water quality constituents, along with equipment/machinery and infrastructure variables. Summary monthly information is compiled and provided to the Board through the Board Agenda Packet, and supplemented as necessary. A summary of highlights is presented annually. Attachments

5 9 Figure 1. Water Year 2016 Monthly Rainfall Totals vs. Average Monthly Rainfall 8 7 Monthly Rainfall Totals, inches Oct Nov Dec Jan Feb Mar Apr May Jun July Aug Sept Average Rainfall WY 2016 Actual Rainfall

6 Figure 2. Tampa Bay Water Delivery Water Year 2016 Compared To Water Year million gallons per day % increase mgd WY mgd WY Tampa Bay Water Delivery mgd WY 2015 Water Year to Date Delivery WY 2016 Water Year to Date Delivery

7 Oct-14 Nov-14 Dec-14 Jan-15 Feb-15 Mar-15 Apr-15 May-15 Jun-15 Jul-15 Aug-15 Sep-15 Oct-15 Nov-15 Dec-15 Jan-16 Feb-16 Mar-16 Apr-16 May-16 Jun-16 Jul-16 Aug-16 Sep Figure 3. Consolidated Wellfield Production 12 month running average through May 31, 2016 = 78.9 MGD 90 MGD Actual production WY 2015/2016 Target Wellfield Production WY Month Running Average Regulatory Limit Production, million gallons per day

8 Figure 4. Regional Reservoir Storage 8 7 Oct BG Oct BG Monthly Diversions (Billions of Gallons) Storage Volume (Billions of Gallons) Oct-15 Nov-15 Dec-15 Jan-16 Feb-16 Mar-16 Apr-16 May-16 Jun-16 Jul-16 Aug-16 Sep-16 Oct-16 Month Reservoir Influent Reservoir Effluent Cumulative storage -4