Projections

We have made the following charts large so they will be easier to see.  If you set your monitor resolution high then one graph will fill the screen.  The graphs show the predictions made by the DNR for how much water will be allocated to each district, how much each is expected to use and how much of a surplus or shortage each is expected to have.  Note, there are a very large number of assumptions built into these predictions and hence they should only be used a very rough guide.  Think of them the same way you do next years weather forecast. 

The blue line is the projected allocation.  The allocation is the district's share of the virgin water supply.  This is made up of the precipitation, seepage from the aquifer, and seepage that would have come from the aquifer if it had not been intercepted by ground water pumping.  All three of these numbers are estimates with precipitation being the most accurate estimate of the three.

The linear allocation is the allocation trend line.  For each of the three districts, this trend line increases over the 40 year simulation .  This means the simulation works under the assumption that the virgin water supply increases by a small amount over the next 35 years.

The red line is the projected depletions.  This is the projected Consumptive Use.  Consumptive Use is the decrease in the stream flow caused by activities of man.  This includes ground and surface water irrigation, evaporation from the reservoirs, seepage from the stream into the aquifer.  The affect previous year's groundwater pumping has on the stream today is an estimate made by the Computer Simulation.  This is one of the most important estimates.

The linear depletion is the depletion trend line.  For each of the three districts, this trend line increases over the 40 year simulation .  This means the simulation works under the assumption that the negative effect of man on the stream increases by a small amount over the next 35 years.

The yellow area is the amount of the depletion greater than or less than the allocation.  Any yellow below the 0 line means that district used more water than it was allocated.  If the yellow is above the 0 line, then the district could have used more water than it did.

The light blue area is the yellow area averaged over three years.  This smoothes the surpluses and shortages out.  The Settlement Agreement allows for a 5 year average unless it is a water short year, in which case it is a three year average.  The light blue area under the 0 line means the district must make a reduction in Consumptive Use to stay in compliance.

We include the year designation on the axis on some of the graphs and not on others.  The years really don't matter, as it is all a project with little chance of matching reality.  However, the years give an idea of how things may work.

What the graphs reveal.  

For the URNRD, the depletion trend remains below the allocation trend line.  For the MRNRD and the LRNRD, the depletion trend lines grow faster than the allocation trend line.  This means that the Middle and Lower are increasing their usage faster than their allocation and, hence, will overuse their allowance more frequently.

The first four charts show the projections, assuming things continue as they are now.  The irrigation retirement programs do not happen, and the Tri Basin consume their legitimate excess share of the mound.

The bottom set of charts show the districts with the assumption that CREP & EQIP do exist and the Tri Basin does not consume its Mound credit. 

The last chart shows the projected Mound credit as used by the computer simulation that allowed us to generate these graphs.   The actual Mound credit in 2003 was 9,500 acre feet.

Recommendation

It took us a lot of work to piece the various data together and create these graphs.  There is no one source for the data, and this information is only now available to the people setting policy because we gave it to them.  Tri Basin NRD data and how it affects the overall Basin is very difficult to find.  We believe the DNR should do a set of Model runs that simulate the same things these graphs do.  Then present this information to the NRDs for their consideration.  We think this information should be provided to the NRDs and the public by the DNR so that the policy makers can take into consideration as much information as possible in making their choices.   Any thing short of this makes all policy decision a  guess by those setting policy.  Even with the simulations it is a guess since the simulations are based on a large number of guesses.  However, the State has committed itself to live by this system.