Looming Monster

Technical Discussion of the Lag Effect

The NDNR has provided limited information to the public on the subject of the Lag Effect.  What it has provided to the public is contradictory to other information it has provided elsewhere.  This article will attempt to make sense of the numbers.  This is a technical discussion for those who want to know the numbers.

Definitions

RRCA - Republican River Compact Administration.  One member from each of the three states, Nebraska, Kansas, Colorado.  Roger Patterson is the NE rep.

NDNR - Nebraska Department of Natural Resources

Cell = The RRCA has divided the 19,000,000 acres of the basin into 53,000 one square mile cells.  The cells do not match the existing section lines.  Each cell is assigned a value for soil type, recharge rate, irrigation type, precipitation, etc.

QR - Quick Response well. Unofficially any well within 1 mile of the center of the stream.  The NRDs are being told they are to determine what well is a quick response well.  There is a great deal of confusion on who defines this and how many wells and acres fall in the QR category.   This number matters, as this type of well is assigned a Depletion Factor that is higher than other types of wells.  These wells are also subject to much greater restrictions.

Upland - Any well that is not a quick response well.

Depletion Factor - The effect a well has on the baseline flow of the stream.  This is a key number and has been impossible to obtain.  We estimate it, but there is no official report of what these numbers are.  In fact, the NDNR says this set of numbers is unobtainable.  We disagree and have provided a methodology that would allow their retrieval.   This suggestion is ignored, as the NDNR does not want to release these numbers.

Baseline Flow - This is the flow in the stream that originates from the aquifer.  The stream flow is the amount of water in the stream, including runoff from precipitation.  Stream flow includes baseline flow plus runoff.

Public Statements by the NDNR made at numerous meetings and confirmed in emails to WaterClaim:

• The Average Lag Effect is about 33% for quick response wells.
• The Average Lag Effect is about 16% for upland wells.
• The Lag Effect is like a depreciation schedule.  The water we pump this year will cause a depletion of the baseline flow in future years.
• Almost 100% of all aquifer pumping will cause a depletion to the baseline flow at some point in time.  It may be as few as 3 years and as many as many decades.

• Pumped	Year	1	2	3	4	5	6	7
  Yes	1	33.3%	33.3%	33.3%
  Yes	2		33.3%	33.3%	33.3%
  Yes	3			33.3%	33.3%	33.3%
  Yes	4				33.3%	33.3%	33.3%
  No	5
  		-	-	-	-	-	-	-
  		33.3%	66.6%	99.9%	99.9%	66.6%	33.3%	0.0%

  This chart has been confirmed by Ann Bleed, in a July 12, 2004 email, as an accurate representation of how the Lag Effect works.

  "This is what I understood you to say at the meetings in Imperial and again in McCook.  Is this correct?

  Close to 100% of all ground water pumping will eventually affect baseline flow.  It is simply a matter of when.

  For a 33% quick response well it would be    [table above inserted]

  If a QR well has a 33% depletion affect on the stream, then it would have a consumptive use of about 33% of pumping in the year the pumping took place.  In the year after the pumping took place, it would have another 33% consumptive use affect, etc., as in the table above.

  Table assumes pumping happening in the first 4 years with no pumping in year 5.  By year 7 there is no further affect on the stream from the well’s pumping in years 1-4. 

  Am I understanding the methodology correctly?"  -- quote from our email to Ann Bleed.

  Response - "I think you got it. Ann"

Note, WaterClaim is not saying this is correct.  We are simply analyzing the information that we have been provided.  In fact, we will demonstrate that this explanation that has been repeatedly provided to the public (by the NDNR) cannot be correct.

According to the NDNR, the total 1998-2002 average per year QR volume is 342,455 acre feet. 

Click to see worksheet showing the consumptive use, if one applies the percentages given by the NDNR for QR and Upland wells.

As can see, the consumptive use quickly balloons to a 1:1 ratio on quick response wells; and for upland wells, the ratio will hit 1:1 within seven years.  This is an impossible number, as it means that the basin's consumptive use would be 1,083,530 acre feet per year.  The total allocation for the 5 year period is 281,007.  This includes the water available for surface water users. 

Therefore, we conclude that what the NDNR is telling the public and the NRDs cannot be correct.  Not even Kansas is claiming that consumptive use is greater than a fraction of the actual pumping.

This leaves several possible alternative explanations.  The NDNR misspoke, and they did not mean what they have been telling everyone at multiple meetings.  Instead, one of the following ideas might be correct:

1. The Depletion Factor is much less than what the NDNR is reporting.
2. The Depletion caused by pumping is delayed years before the depreciation begins to take effect.
3. The number of QR wells is much less, but the Depletion Factors for these QR wells are much higher than 33% while the Depletion Factors for upland wells are close to 0.
4. 100% of the well pumping does not eventually affect the baseline flow.

The problem is that we do not know the answers, but the NRD is being asked to implement changes that will dramatically affect the communities and do so with insufficient information.  When we can demonstrate that the explanations given are incorrect, it should cause the decision makers to pause long enough to obtain clarification from the experts.