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Home My WebLink About5 - Presentation - Update on Boulder's water yields, operations models and reliability criteria ame& Assessing Boulder's Water Supply Reliability December 21, 2009 Lee Rozaklis AMEC Earth and Environmental (formerly Hydrosphere) lee. rozaklis@amec.com ameO Outline Boulder's Water Supply Reliability Criteria Description of the Boulder Creek Watershed Model Modeling Water Supply Reliability Results of Model Runs ameO Boulder's Water Supply Reliability Criteria Boulder's Water Supply Reliability Criteria ame& Adopted by City Council as part of 1988 Raw Water Master Plan Based upon the recognitions that: No municipal water supply system can be 100% reliable There are trade-offs between reliability and economic/environmental costs (Water supply goals during droughts) ■ Up to 1-in-20 year severity - satisfy all water needs ® 1-in-20 year to 1-in-100 year severity - minor to significant demand reductions, subject to maintaining viability of permanent landscaping ® Up to 1-in-1000 year severity - supply "essential uses" (indoor domestic, commercial, industrial, fire fighting) ame& Boulder Creek Watershed Model How It Works ame& Represents streams, ditches, 152 DEMN 38 reservoirs, water rights, demands 296 150 146 RESV 4 198 133 and return flows as a network of LINK 163 LINK 156 LINK 140 L LINK 161 LINK 40 LINK 411 links and nodes having different LINK410 132 ranks or priorities. DECR 1 147 306 LINK 139 LINK 14 146 LINK 412 136 LINK 407 B me Re rvoir ■ Allocates native water to Water ri C]htS -INK 416 129 INK 145 AI based upon their relative priorities, LINK 138 given supplies, demands, decree DEMN33 limits and stream structure. MB D MB cGinn Ditch Cottonwoc Solves allocation using linear L202 Ditc programming L203 LINK417 DECR 100 L201 184 DC79 334 DEMN 79 :97 MB Erie Municipal DC96 Demand Solves each time step several times DC99 00 282 183 DM45 MB South BOUT anyon to represent operation of exchanges, L199 itch releases, etc., that are driven by DECR37 rules other than water right priorities Sc rer itch What it Simulates ame& ' All major aspects of Boulder Creek basin. hydrology, water rights, imports, exports, diversion/storage facilities, operating policies, water uses, return flows f xay ~J Operation of CBT and Windy Gap projects and deliveries to ..1 Boulder Creek users s„ ,Y \ Ohi7C•IT1 G fJ ' Calls by water rights' _ downstream of Boulder Creek BCWM - Hydrology ame& 17 Inflows: F Woodland Creek at Skyscraper Reservoir ■ Jasper Creek at Jasper Reservoir Middle Boulder Creek gain at Nederland .P 116i - z, A North Boulder Creek at Silver Lake ■ Caribou Creek ■ Como Creek/North Boulder Creek gain at Lakewood ■ North Boulder Creek gain at Orodell L Y`~ ■ Middle Boulder Creek gain at Orodell~K ■ Four Mile Creek y.';. ■ South Boulder Creek at Gross Reservoir ■ South Boulder Creek gain at Denver's diversion r ■ South Boulder Creek gain at Lafayatte diversion ti ■ Boulder Creek gain - Orodell to 75t" Street ■ Boulder Creek gain - 75t" St. to Lower Boulder Ditch, ,t ■ Boulder Creek gain -Lower Boulder Ditch to Coal Cr. ■ Boulder Creek gain - Coal Cr. to St. Vrain confluence ■ Colorado River at Hot Sulphur Springs ,ALI cam BCWM Water Rights ' 572 individual surface water rights diverting from: • North Boulder Creek • Middle Boulder Creek IN THE DISTRICT COUWT OF OOLLOER COLA. 7. COL; The South Boulder Creek e Dtth In the .hitter of the Vrlarvty of Y'ater Rlgh[5. • Boulder Creek ' Exchange rights (Boulder, Boulder White JrI a a Rock Ditch, Lafayette, Louisville) ~~f~J~;`~a >k4-r .n., .,o„r/.T-q r%s.«t nr.CF,.,.y (Y.9G r%!l- N X.! h... a d ifs ..,T rr I 'd 11, ' Instream flow rights .a „M,M1 ' Downstream South Platte water rights (represented as calls) ' Boulder Creek basin water rights not modeled: ■ Groundwater rights ■ Surface rights on minor tributaries • Storage rights for small reservoirs • Small direct flow rights on upper reaches BCWM - Imports and Exports ame& Imports: ' Colorado-Big Thompson via Boulder Feeder Canal ' Windy Gap via via Boulder Feeder Canal Exports: _ Colorado-Big Thompson via South Platte Supply Canal (Lower Boulder/ Coal Ridge ditches) ' Models operation of CBT project system in order to estimate quotas for model runs using pre-1955, paleo and climate change hydrology BCWM - Diversion & Storage Facilities ameO Municipal points of diversion • Boulder • Lafayette 2 • Louisville • Denver • Erie (South Boulder Creek portion):' • Nederland,, rt F s~ <ti 4 Irrigation Ditches - ■ 24 irrigation ditches on Boulder Creek ■ 18 irrigation ditches on South Boulder Creek • Reservoirs ■ Barker Reservoir ■ Boulder's watershed reservoirs (7) • Marshall Reservoir ■ Waneka Reservoir • Baseline Reservoir M~ • Val mont/Leggett/H ill crest Boulder Reservoir + • Goose Haven Reservoirs • Six Mile Reservoir • Panama Reservoir • Skyscraper, Park , Jasper Reservoirs (optional) BCWM - Operating Policies ame& All users: Use direct flow before storage Boulders water supply system reservoir release rules ■ exchange rules y r 1 ■ Boulder Reservoir operations' ■ Instream flow program ■ Drought recognition & response = ' Lafayette's water supply system ■ Reservoir release rules ■ Exchange rules F `9. ' CBT Project y' supplemental supply deliveries _ Boulder Creek Basin Network ame& Boulder Creek Watershed for the City of Boulder - Hydrosphere Excel CRAM Network Schematic cansmN nkpWwopx~nen Aron - t~is / /-w I~ - - ` \ - - tt t, 5 J l i q z ,1 - J How it Operates ame& ' Time series of variable natural stream flows, climate data and trans- basin imports: -historical/recorded for 1907-2006 -tree ring-derived for 1566-2002 -climate change scenarios ' M&I uses: fixed annual demands ' Irrigation uses: fixed acreage, variable demands due to climate variations ' South Platte calls: variable based upon climate/ET ame& Tree Ring-Reconstructed Natural Flow, Boulder Creek Near Orodell 120 period of record 100 80 as m L V 60 40 20 0 1666 1616 1666 1716 1766 1816 1866 1916 1966 Year ameO Modeling Water Supply Reliability Boulder's HistorY in ModelinJ SYstem ReliabilitY am 1988: Separate water rights and system models; "firm yield" analysis based on 1950-1985 hydrology; extrapolated stochastic analysis (10 x 100-year traces) based on 1950-1985 hydrology. Mid 1990s- Integrated water rights and system model, expanded period of record (1950-1994). 2003: Use of tree ring-based hydrology and climate data; drought recognition and response triggers developed and incorporated into model. Extension of gage-based hydrology to cover 1907-2006 2006: Incorporation of climate change scenarios into model as part of Climate Change Vulnerability Study Previously: Firm Yield Approach ame& 35000 no reduced deliveries, even durin , drourhts 30000 Annual Deliveries 25000 a~ 20004 - m U- Annual Minimum Storage Contents - - - - - - - - ` 15004 10000 systeri storage 5000 - ,crashes" at end of critical drought 1703 1728 1753 1778 1803 1828 1853 1878 1903 1928 1953 1978 Problems with Firm Yield Approach ame& ' Based upon an arbitrary critical drought ' Unrealistic portrayal of how system would operate (overstates the system's capabaility) ' Assumes an accurate crystal ball ' Does not provide useful information or options to decision makers ' Sometimes useful in situations where major growth in future water demand is expected Now: Reliability Assessment Approach ame& 35404 reduced deliveries in response 34000 to ctrou 1~t tr1- ,ors------------------------- Annual Deliveries 25000 F 'V400 CL) U- v A nual Minimum Storage C ntents L _ A000 10000 system storage is drawn down but 5044 does not empty 0 1703 1728 1753 1778 1803 1828 1853 1878 1903 1928 1953 1978 Benefits of Reliability Assessment Approach ame& ' Tests the system against a range of droughts ' Allows for evaluation of trade-offs between varying levels of reliability ' More realistic portrayal of how system would operate ' Does not assume foreknowledge ' More intuitive to decision makers ' Particularly useful when dealing with uncertainty (i.e. climate change) Assessing Boulder's Water SuppIY ReliabilitY am Impose a specified municipal water demand level onto variable time series climate and hydrologic data Municipal demands reduced during droughts according to Drought Plan response triggers and water use reduction goals "Scoring" based upon Boulder's reliability criteria Allows for evaluation of alternate demands, drought response strategies, reliability criteria ameO Results Results Caveats ame& Boulder's municipal demand of 28,600 AF/year (probably overstated) No carry-over in CBT project storage (currently allowed but not a permanent policy) No change on Boulder's drought response thresholds or system operating rules (study did not look at coping mechanisms) No consideration of Colorado Compact calls or other limitations on CBT's ability to divert entire physical supply except for local bypass requirements. Summary of Results -Boulder Water Supply came 1-in- 1-in-20 1-in-100 1000 year year year Emission Model criterion criterion criterion Scenario Type Year met? met? met? Drought Plan (300 years) yes yes yes BASE CASE es es es 131 Wet 2030 yes yes yes 131 Mid 2030 yes yes yes 131 Dry 2030 yes yes A113 Wet 2030 yes yes yes AlB Mid 2030 yes yes yes A113 Dry 2030 no yes yes A1B Dry3 2030 no A2 Mid 2030 es es es A2 Dry 2030 es es 131 Wet 2070 yes yes es 131 Mid 2070 yes yes yes 131 Dry 2070 yes yes yes Al B Wet 2070 yes yes yes AlB Mid 2070 yes yes yes A1B Dry 2070 no yes Al B Dry3 2070 no yes yes A2 Mid 2070 no yes yes A2 Dry 2070 no Note: "yes" = criteria met in each of the 11 traces Summary of Model Results ame& # of "events" 1-in- maximum average of 1-in-20 1-in-100 1000 % of years (1 or more event maximum delivery consecutive years year year year with reduced with reduced length, delivery reductions, Emission Model criterion criterion criterion deliveries deliveries) years reduction (AF) (AF) Scenario Type Year met? met? met? Avg Max Avg Max Avg Max Avg Max Avg Max Drought Plan (300 years) yes yes yes 3% 6 4 6552 3313 BASE CASE es es es 2% 3% 3 5 4.8 7 2526 5334 1247 1604 B1 Wet 2030 yes yes yes 0% 0% 0 2 0.5 2 524 1573 1159 1573 B1 Mid 2030 es es es 4% 5% 5 8 6.6 11 2848 5334 1369 1899 B 1 Dry 2030 yes yes 7 11 6.3 10 4138 9377 1419 1800 Al B Wet 2030 es es es 0% 0% 0 2 0.3 1 295 1573 719 982 Al B Mid 2030 es es es 4% 5% 5 7 5.8 7 3120 5334 1371 1724 Al B Dry 2030 no yes yes 7% 11% 10 16 7.1 10 3953 5838 1448 1864 A1B Dr y3 2030 no 23% 27% 27 36 11.3 14 10120 1847 2232 A2 Mid 2030 yes yes yes 3% 5% 5 6 5.2 6 2736 5334 1286 1656 A2 Dry 2030 es es 16 22 8.5 11 4426 5838 1484 1716 B1 Wet 2070 es es es 0% 0% 0 2 0.5 2 426 1573 893 1234 B1 Mid 2070 yes yes yes 2% 3% 3 6 4.2 6 2533 5334 1217 1713 B1 Dr 2070 es es es 3% 5% 4 6 4.8 6 3098 5838 1414 2044 Al B Wet 2070 yes yes yes 0% 0% 0 2 0.3 1 295 1573 719 982 AlB Mid 2070 yes yes yes 2% 3% 3 6 3.7 6 2531 5652 1106 1818 Al B Dry 2070 no yes % 16% 18 26 8.9 13 9657 1857 2253 Al B Dry3 2070 no yes yes 4% 6% 6 10 5.5 7 3829 5838 1481 1755 A2 Mid 2070 no yes yes 5% 6% 7 10 5.8 7 5933 9036 1431 2078 A2 Dry 2070 no no no 21% 26% 23 29 12.8 17 10475 12332 2153 2467 (Averages and maxima for the eleven 437-year traces in each scenario) ame& Reduced Deliveries - Base Case, Trace 11 2500 2000 period of record 1500 m a~ UL a 1000 500 0 1566 1616 1666 1716 1766 1816 1866 1916 1966 ame& Reduced Deliveries - 131 Wet 2070, Trace 24 1800 1600 1400 period of record 1200 1000 a~ 800 a 600 400 200 0 1566 1616 1666 1716 1766 1816 1866 1916 1966 ame& Reduced Deliveries - A2 Dry 2070, Trace 257 10000 9000 8000 7000 period of 6000 record Q 0 5000 m L Q 4000 3000 2000 1000 0 1566 1616 1666 1716 1766 1816 1866 1916 1966 Seasonal Changes in Flow ame& Scenario Annual Winter Spring Summer Fall Base Case 0% 0% 0% 0% 0% B1 Wet 2030 7% 19% 19% -18% 15% B1 Mid 2030 -2% 4% 13% -28% -7% B1 Dry 2030 -3% 9% 7% -21% -1% Al B Wet 2030 12% 21% 24% -8% 14% A1B Mid 2030 -2% 5% 13% -25% -12% Al B Dry 2030 -4% 19% 8% -26% 6% A1B Dry3 2030 -6% -3% 2% -23% 0% A2 Mid 2030 -1% 8% 10% -22% 4% A2 Dry 2030 -5% 8% 7% -28% -2% B1 Wet 2070 9% 38% 27% -28% 23% B1 Mid 2070 0% 23% 16% -27% 2% B1 Dry 2070 0% 62% 15% -34% 9% Al B Wet 2070 16% 45% 35% -21% 27% All B Mid 2070 5% 46% 25% -35% 16% Al B Dry 2070 -4% 65% 15% -44% 12% AI B Dry3 2070 -3% 32% 13% -35% 7% A2 Mid 2070 0% 47% 20% -41% 11% A2 Dry 2070 -4% 62% 19% -49% 0% i ame& Change in Lower Boulder Creek Irrigation Demands 90% 80% 70% 60% 50% 40% 30% 20% 10% - - - - 0% Base B1 B1 B1 Al B Al B Al B Al B A2 A2 B1 B1 B1 Al B Al B Al B Al B A2 A2 Case Wet Mid Dry Wet Mid Dry Dry3 Mid Dry Wet Mid Dry Wet Mid Dry Dry3 Mid Dry 2030 2030 2030 2030 2030 2030 2030 2030 2030 2070 2070 2070 2070 2070 2070 2070 2070 2070 ame& Supply vs. Demand - Base Case 35000 30000 25000 72% 20000 Q 15000 10000 5000 0 El 4 Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep ❑ Orodell Supply ■ Irrigation Demands ameO Supply vs. Demand - Al B Dry3 2030 35000 30000 25000 57% 20000 LL m L Q 15000 10000 5000 0 Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep ❑ Orodell Supply ■ Irrigation Demands ame& Supply vs. Demand - A2 Dry 2070 35000 30000 38% 25000 20000 m a 15000 10000 5000 of E o o r---1 r Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep ❑ Orodell Supply ■ Irrigation Demands ame& Irrigation Demands vs. Deliveries 120000 100000 80000 60000 a 40000 20000 0 ~e eo ~o !bo ,~o 10 10 10 10 6~ Ga ~o ~o ~yo do ~yo ~o ~yo ~yo ~yo ~yo ~yo do ~o ~yo ep ~o do ~o a e ~e~ fie'` e1``a o~ `a `a a ~ ti0 ^S~ o6 P~ P~ het`` ~O P~ Q►~ Q, P~~ Qi Qi P~ Q, P~~O e P P ■ Diversions 0 Shortages