Delaware River Basin Commission

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1 New York City Water Supply System is greater than 100 years old Provides water to 9 million people 1.3 billion gallons per day on average The Delaware System provides 50% of the City s water supply need The Catskill System Provides 40% The Croton System Provides 10% (up to 30% during drought) Delaware River Basin Commission Formed in 1961 by President Kennedy and the Governors of Delaware, New York, New Jersey and Pennsylvania to coordinate the use of the Delaware River Basin between the States and the City of New York. The agreement allows NYC to divert up to 800 mgd from the basin, while NJ is permitted 100 mgd.

2 Drought Drought Case Study: Future Climate Change Scenario vs. the NYC Drought of Record Some projected droughts rival the drought of record in intensity and duration Source: CCSR

3 NYC Precipitation Climate Change Precipitation Projections Range of NASA GISS projections for average precipitation increases: 2.5%-7.5% by the 2050s 7.5%-15% by the 2080s Precipitation intensity (avg. amount of rain on a given day) could increase between 8%-9% by 2050s* Number of precipitation events is expected to increase between12%-13% by 2050s* *Source: Northeast Climate Impacts Assessment, 2006.

4 Recent Severe Storms in NYC October 11, 2007 DEP rain gauge in northern Queens measured total rainfall of 2.66 inches August 8, 2007 National Weather Service rain gauges in metropolitan area measured up to 3.3 inches of rain within a two-hour period (a 25-year storm). DEP s rain gauge in Bay Ridge measured total rainfall of ~ 4.5 inches July 18, 2007 DEP rain gauges measured 2.67 inches total in Northern Queens. 3-5 inches in a 4 hour period (some spots go 3 inches in an 1 hour period) April 15, 2007 National Weather Service s rain gauge at LaGuardia Airport measured 6.69 inches total. 7 inches most in northern Manhattan greatest since September 1882 Previous notable storm was on September 23, 2004 where 2.52 inches accumulated in Central Park in an 1 hour period Potential Climate Change Impacts on New York City Reservoir Watersheds Mean temperatures are expected to increase by 3 to 5 F by the 2050s, and 4 to 8 F by the 2080s Greater temperature and evapotranspiration Less water More intense heat waves will mean increased water demand, increased evaporation, and possibly increased eutrophication Warmer winters may alter streamflow patterns Most GCMs suggest an increase in annual precipitation of up to 15 percent by the 2050s, while pointing towards increases in both flood and drought extremes Greater precipitation More water More intense precipitation Greater turbidity, lower water quality?

5 Climate Change Integrated Modeling Project Analyze NYC s complex water supply network resiliency to climate change. Project will occur in two phases: Phase I: Use sensitivity studies to study existing modeling system WOH (90% of supply): water quantity, incl. system indicators like probability of refill, reservoir storage levels Testing of water quality parameters in indicator reservoirs: turbidity (Schoharie) and eutrophication (Cannonsville). Phase II: focused from results of Phase I, will use upgraded models and climate data sets System wide recommendations WOH and EOH water quantity Entire system testing of water quality Catskill system turbidity and Delaware system eutrophication DRBC - FFMP Delaware River Basin Commission - Flexible Flow Management Program Usable Storage (%) L1 L2 40 L3 Watch Current Plan - Discharge Mitigation - Fisheries - 35 mgd L4 Warning 30 L5 Emergency /15 10/15 2/15 0 6/1 7/1 8/1 9/1 10/1 11/1 12/1 1/1 2/1 3/1 4/1 5/1 6/1 Date 110 Future Plan - Increase NJ s allotment - Detach NYC releases from the location of the salt front in lower Delaware Basin during a drought emergency. - NYC would still make releases, but at a fixed rate independent of the salt front. Usable Storage (%) 100 L1-a L1-b 90 L1-c /15 2/ /1 7/1 8/1 9/1 10/1 11/1 12/1 1/1 2/1 3/1 4/1 5/1 6/1 Date

6 Water Supply Repair Needs Leak in the Rondout-West Branch Section of the Delaware Aqueduct Leaking between 20 and 35 mgd Two known primary locations of concern: Wawarsing & Roseton Currently supplying 50% of the City s water 600 MGD Reliable capacity declining 900 MGD to 840MGD Wawarsing Roseton Water Supply Need for Repair Augmentation Need (mgd) Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Supply to Eliminate Maximum Shortfall Supply to Eliminate 95th %ile Shortfall Supply to Eliminate 90th %ile Shortfall Supply to Eliminate 75th %ile Shortfall Supply to Eliminate 50th %ile Shortfall 325 mgd Year 1 Year 2 Year 3 Year 4 Outage Duration

7 Programs Being Evaluated to Meet Need DEP is currently evaluating alternate water sources and system optimization methods to provide the water needed during the repair of the RWB Tunnel. These include: Redundant tunnels Optimization of the existing system Hudson River Groundwater Tunnel Alternative

8 Optimization of Existing System Maximize use of the existing water supply system via conservation measures, reclaimed wastewater and modifications to existing water supply infrastructure. Hudson River Pump New York Harbor or Hudson River water for drinking water purposes Schedule: Years Issues: Very high operations cost due to energy needs. Difficult to turn on and off. Public may be resistant to drinking what they perceive to be lower quality water. Could impact the Hudson River salt-front.

9 Groundwater Groundwater Capacity Benefits: 10 to 80 mgd continuously, with potential for an additional short-term supply capacity of up more than 100 mgd Capital Cost Estimates Are High due to level of treatment necessary Schedule: 1 to 21 years Sustainable supply, not susceptible to drought or climate change.