Broad interest in local water issues was evidenced by the fact that over 50 residents from SaddleBrooke, Oracle, and Oro Valley filled the meeting room at Columbia University's Biosphere campus Jan 23 to attend the second of two Oracle Water Roundtable meetings. 

Oracle residents Linda Leigh and Ann Woodin hosted both events.

The first Water Roundtable meeting was a daylong event held last March and was closed to the public and the press. 

The primary purpose of the first meeting was to determine what is known about this area's groundwater supply.

The original panel consisted of 23 participants including executives from Robson Communities Inc. and representatives of Anam Inc., two development companies whose projects would add nearly 100,000 people in the Oracle Junction area at buildout. 

According to Woodin, the results of the first meeting were inconclusive.  She summarized the results by saying, "at the present time there is not sufficient hard scientific data to assert that there is or that there is not enough retrievable groundwater to supply the proposed developments" as called for in the Pinal Comprehensive Plan near Oracle Junction. 

According to information in Pinal County documents, the County Comprehensive Plan authorizes development projects that would add about 190,000 people, primarily clustered around Oracle Junction.  Of the 19,000 approximately 120,000 would depend on water from the aquifer that supplies Oracle. 

The purpose of the second roundtable meeting was to give the public a chance to ask questions about the water situation. 

Only two of the original 23 participants presented material at the second meeting, both were scientists: Robert Scarborough is a geologist with the Arizona Desert Museum and Stan Leake is a USGS hydrologist.

Robson and Anam representatives did not attend the second meeting. 

Scarborough gave an overview of the geology of the area and Leake covered the hydrology of the regional aquifer that lies under Falcon Valley, north of the Pinal/Pima county line.

Leake was asked if the regional aquifer could sustain 120,000 additional folks and still attain "natural safe-yield," a condition where the amount of water pumped is equal to the amount naturally recharged. 

Leake said that current estimates for natural recharge to the regional aquifer indicate that the amount of water pumped would exceed the natural recharge and the aquifer would decline without artificial recharge. 

The only source of water for artificial recharge is CAP water, which would have to be piped up to the regional aquifer to prevent water level decline.

Leake was asked what possible consequences could result if the wells supplying the developments authorized by the Pinal Comprehensive Plan were placed over the deepest part of the aquifer at Oracle Junction. 

Leake said that placing wells water in the Oracle Junction area to supply 120,000 people would worsen the overdraft problem for communities south of Oracle Junction.

According to the Northwest Explorer, water levels at wells in Oro Valley are already declining at an alarming rate. Water levels at 6 of Oro Valley's well sites have dropped more than 20 feet in the last 2 years.

Leake said that groundwater from the regional aquifer moves south towards Tucson at a rate estimated between 1,140,478,500 and 1,792,180,500 gallons per year.  Leake's maps showed that this water passes through a relatively narrow channel under Oracle Junction. 

Leake explained that massive pumping in the Oracle Junction area would intercept much of this groundwater instead of allowing it to flow under wellheads south of the junction.

The principle of using high pumping rates to slow water movement in an aquifer is the basis of a strategy Robson says they will implement to protect the aquifer from the Page-Trowbridge radiaoctive/toxic-waste landfill (PTRL). 

Robson plans to build their SaddleBrooke Ranch project directly adjacent to PTRL, which lies a few miles to the northeast of Oracle Junction. 

Robson executives have said the company would place the high-volume wells for the golf courses near the landfill so as to retard the migration of contaminants should PTRL suffer a massive leak. 

Robson executives also contend that regular testing of the water from the golf-course wells would provide early detection of a leak and allow swift corrective action to be taken, limiting harmful effects.

Leake also outlined several consequences that can arise from depleting an aquifer, one of which is land subsidence. 

Land subsidence occurs when the water level in an aquifer drops and the land over the aquifer sinks to fill in the space where the water used to be. Subsidence can cause fissures in the earth. 

Potential subsidence is of interest because PTRL lies over the regional aquifer. 

Fissures around or through the landfill could release contamination to the aquifer and have significant negative effect on the financial and physical wellbeing of the people dependent on the groundwater. 

A SaddleBrooke resident noted that because groundwater moves under PTRL then south towards Tucson, a leak in PTRL could compromise the financial and physical health of people living in Catalina, Sun City Vistoso, Oro Valley and Eagle Crest, a 925 house development currently under construction just south of Oracle Junction.

The following map illustrates.

Because Leake wanted to keep the discussion focused on the big picture, he discouraged discussion of the PTRL situation.  As a result, the fact that the federally regulated contaminant Toluene was twice confirmed to be present in groundwater sampled from beneath PTRL was not addressed.