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Meeting: Santa Fe County Hydrology Model Development ~ Click here for Santa Fe County Hydrological Study Slide Show
and Application Presentation
Location: Agua Fria Fire Station
Date: March 16, 2006 6:00 pm - 8:00 pm
Presenters: Steve Wust, Director, SFCounty Water Resources Dept
Karen Torres, SFCounty Hydrologist
Cindy Arditto, INTERA Hydrologist
John Utton, SF County, Water Rights Contract Attorney
SUMMARY REPORT submitted by TRA Board Member Bob O’Connor
A year and a half ago, County Commissioners began to analyze how the County had been building out its current water infrastructure in anticipation of the long-talked-about Northern New Mexico Water Authority. In the past, water infrastructure followed the same development path as road infrastructure, i.e. developers for each subdivision built the road infrastructure and the water infrastructure then donated it to the County to maintain and operate. The conclusion the Commssioners came to was that this system was too haphazard, and entirely developer and location driven.
The City and County concluded they needed to pool their resources and collaborate on the development of a single, consistent, scientific model that would help Santa Fe plan map out its water needs and water use strategies over the next 40 years, and to provide reliable data on 4 Critical Criteria:
1) How to develop and maintain a sustainable water supply
2) How to do this in a way that minimizes the impact on existing domestic wells and public utility water users
3) How to do this in a way that minimizes the impact to existing streams/springs
4) And how to do all this at a reasonable cost to taxpayers
The plan needed to be done based on:
1) Good hydrology data
2) Data that takes into account current and future population distribution
3) Data that took maximum advantage of existing water infrastructure
4) Data that noted the proximity to existing large wells
5) Data that identified the location and proximity to existing domestic wells
A company named INTERA was hired as a consultant to develop a 3-D hydrology model that would map the location of the aquifer and provide recommendations for Optimal New Well Locations that would:
1) Provide the most sustainable yields
2) Have the least impact on the aquifer and springs
3) Be most proximate to existing water infrastructure
4) And could be undertaken at the most reasonable cost.
INTERA mapped:
1) All known geological/hydrological formations and structures
2) All geological fault lines
3) The location of the aquifer
4) The location of surface and ground water sources
5) The location of current pumping locations and how much water was being extracted
6) And identified pertinent stream volume and underwater spring data
This data was complied from many sources but primarily from OSE, USGS, New Mexico Bureau of Geology, New Mexico Resources Bureau, from Buckman Well Field data, from previous hydrology reports considered highly reliable and from LANL.
The model area agreed to is an area that does not include all of Santa Fe County. But is an area which includes the areas most likely to experience growth and human impact over the next 40 years. Without the benefit of a map, the area basically extends South past Eldorado but does not include the Galisteo Creek basin; to the East it ends at the base of the Sangre de Cristo mountains; to the North it extends to the boundary of the Santa Cruz and Santa Clara Rivers; and to the West to goes to the Rio Grande and the base of the Jemez Mountains where all previous studies had ended before.
Using MODFLOW 2000, a publicly available code and CDM code analysis, INTERA basically created a 3-D cartoon of the Area of Interest (AOI) that cut the core into cross sections and in essence mathmatically simulated the relationship between the terrain, the aquifer and the geological structures within the AOI.
INTERA then took all current and projected future City/County water use figures over the next forty years and cross-referenced this data against the 3-D model. They then ran computer simulations that pumped each of the projected 4 new well locations at a rate of 60 gallons per minute/365 days a year/for 40 years to see what kind of stress such pumping would have on the aquifer based on all current known data. This was considered a "maximum pump stress test," and not a measure of realistic water use, in order to push the outer limits on pumping to see the end result.
In simple layman's terms, the idea was to determine exactly how much water was going into the system over time from all available sources and how much water is leaving the system on a daily/monthly/annual basis.
The computer-simulated data was then calibrated or compared against actual known field data. According to INTERA, the results in their model were within a 5% margin of error which is considered in the trade "highly reliable."
This computer-simulated data was then literally laid down against other data on a map of the AOI using a scale of 0 - 100, red being the most undesireable/green being the most desirable. Factors like existing well fields, maps of exisiting domestic wells, existing stream areas, infrastructure, high density population areas, off-limits property like BLM land, City/County land, private property and pueblo lands were all mapped out against this matrix.
This is probably best understood in the graphics which are included in the CD-ROM I will be circulating next week. And from the correlation of all this data as a whole, recommendations were arrived at for the Optimal New Well Locations.
It is important to note that this 3-D Hydrology Model is just one facet of what Steve Wust called the "City and County's Conjunctive Use Strategy," a fancy word for a "mix-and-match" patchwork of possible water sources - public wells/domestic wells/surface water diversion through the Buckman Direct Diversion Project and other sources/the importation of water from outside sources/de-salination/treated effluent/and aquifer recharge injection strategies - all of which are being considered as City/County officials look into the future.
Nowhere however, in all these computations, was there any mention of conservation.
Bottomline, this Hydrology Model Report is an Interim Report. More data is being gathered. Public input has just been gathered. A Final Report with recommendations to the City and County should be ready for review amd comment sometime late April/May 2006.
The Optimal New Well Locations identified in the current report are only recommended sites. There has been no actual well drilling to date.
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