A Reconsideration of the Law of the River in an Era of Scarcity Lawrence J. MacDonnell Attorney and Consultant Boulder, Colorado

Overview 1.We are already depleting as much or more water than the basin reliably yields 2.UB is being asked to prepare itself for a “Compact call.” 3.Changes must be made in LB uses before there should be such a call

Basin Hydrology Early estimates: 17.3 maf at Yuma plus 2.2 maf of depletions=19.5 maf undepleted flows; maf at Lee Ferry BOR, 1947: 16.4 maf at Lee Ferry Tipton, 1965: 13.0 maf at Lee Ferry (low flow 30 year period) Stocton & Jacoby: 13.5 maf at Lee Ferry (long-term tree ring analysis) BOR, 1988: 15.2 maf at Lee Ferry

Basin Consumptive Uses Annual Average Lower Basin mainstream8.0 Lower Basin tribs2.5 Upper Basin3.7 Mainstem res. evap.2.0 Mexico2.9 Total19.1 maf

Lower Basin Consumptive Uses ( average) Arizona -mainstream2.6 maf -tributaries2.2 California -mainstream5.1 Nevada -mainstream0.27 -tribs0.12 –Lower Basin Res. Evap.1.3 Total11.59 maf

COLORADO RIVER BASIN Water Supply (in MAF) Consumptive Uses ( average) Upper Basin RunoffUpper Basin 3.7 Reconstructed from record 15 Res. Losses 0.7 Reconstructed from tree ring studies 13.5 Lower Basin mainstream year low average 13 Res. Losses year low average 11.8 Tribs. 2.5 Lower Basin tribs 3.0? Mexico 2.9 Total Available Water Supply ? Total 19.1

A Compact Call? UB obligated under 1922 Compact to deliver 75 million acre-feet of water at Lee Ferry over running 10 year periods What would happen if annual releases over a given 10-year period from Glen Canyon Dam did not provide 75 maf?

Lingering Unresolved Issues 1: Water for Mexico 1944 Treaty: 1.5 maf/yr Minute 242: bypass kaf/yr “excess” deliveries: ~100kaf/yr 750 kaf/yr from UB: is this legally required? What is the effect of continuing growth of tributary water use in LB? How to include the interrelated groundwater use that reduces tributary streamflows? AZ responsible for bypassed water?

Lingering Issues #2: LB Evaporative Uses 1922 Compact allocates 7.5 mmaf/yr of consumptive use to LB Compact also provides for an additional consumptive use of up to 1 mmaf/yr in LB Evaporation losses from reservoirs and losses from mainstream in LB about 1.3 mmaf/yr How to account for this depletion in basin water supply? Compact negotiators were aware of large losses between Lee’s Ferry and Yuma; tributary inflow was the source of water to offset these losses

Lingering Issue #3: LB Beneficial Consumptive Uses Compact allocated to LB 7.5 mmaf/yr for beneficial consumptive use USSCt decided this was water from the mainstream (clearly wrong) LB consumptively used annual average of 8 mmaf between (now [since 2002] CA cut back to 4.4 but AZ CAP diversions up) Legal status of AZ CAP diversions to replace gw pumping? Are uses “beneficial”? Water delivered vs. water consumed Designate uses of mainstream beyond 7.5 mmaf as unsecured

Some Larger Considerations 1.Return to full basin level framework regarding all sources and uses of water 2.Principle of accountability for all depletions (state budgets; depletions must stay within) 3.User-pays principle 4.Consider fungible consumptive use shares for mainstream water

Summary 1.Basin water supply may already be overused 2.Expectations in every state to increase their consumptive uses; certainly the UB expects to be able to use at least 6 mmaf/yr, 2 mmaf/yr more than at present 3.Not possible without some significant changes in LB uses