Trip Report – 7/19/03
Submitted by Chuck Noe
On Saturday, July 19, 2003 three separate dives were attempted at Goodenough Springs by GSEP team members Chuck Noe, Rick Aurich, Mike Gault, and Lovan Chetty. The conditions encountered were beyond what I imagined possible at this site.
In March of 1975 the Texas Water Development Board issued Report #189 documenting the major and historical springs of Texas. In this report, it was surmised that only two “first-magnitude” springs remained in the state, Comal Springs and San Marcos Springs (a first-magnitude spring is defined as one discharging >100 cf/s). Both San Felipe Springs and Goodenough Springs, near Del Rio were assumed to have fallen below this 100 cf/s discharge rate. In fact, the report stated that the head of water (Lake Amistad) over Goodenough Springs “has probably greatly reduced or even stopped the flow of this spring”. This assumption could not be further from the truth.
While we have continued to witness strong and unabated flow from Goodenough over the past three and one-half years, this latest observation was nothing short of incredible. The discharge we encountered was downright intimidating and made any efforts to penetrate the system foolhardy at best.
Each of us encountered what could only be described as a “violent” flow of turbid water coming from the cave before we entered even the cavern zone. The flow was strong enough to initiate unintentional purging of any regulator that was not perfectly positioned to avoid the water pressure. And pulling forward against the flow required a strong, determined effort.
I managed to reach the anchor/tire at 126 ffw after stopping twice to control my free-flowing backup regulator. By keeping my head ducked into the flow and turning the breathing resistance knob, I had managed to keep my primary regulator from purging unnecessarily. I was able to recognize the tire only by the eye-bolt sticking out of the gravel floor and the attached lines (the tire was completely buried). Reaching forward I managed to hook my hand over the front edge of the tire, which had a washed-out area below and in front of it. I grabbed the continuing guideline (3/16” heavy braided line) and pulled hard on it to verify that its attachment was still intact further in the cave. It was still secure.
At this position, I was experiencing a slightly reduced flow by hiding behind the tire and the warning sign that lies just past it. The plan was to rendezvous with Rick at this point to discuss further penetration. Though I considered the possibility of proceeding further to look for clear water without him, I knew the only prudent choice was to fall back to Rick’s position so that we could both confirm each other’s safety. In addition, I knew that the one-foot visibility would only worsen the dangers of entanglement or being knocked unconscious in the cave. We chose to exit.
We met Mike and Lovan on the buoy-chain while ascending and they decided to exit the water as well (having already encountered the conditions on their first dive). Everybody completed deco without incident and we all climbed back aboard the Swamp Yacht to marvel at what we had experienced.
The conditions witnessed at GE on this dive bring up a number of questions. While a considerable amount of rain (from Hurricane Claudette) had fallen in the surrounding areas earlier in the week, we had grossly underestimated its effect on this spring. I have attached a graphic showing total storm precipitation levels of up to 12.5 inches to the southwest of Goodenough in the Mexican state of Coahuila. There was general heavy rainfall (3”-10”) in a wide swath to the west of Goodenough. What I find surprising is that this recharge translated into such tremendous spring flow in only three days’ time. The porosity of this sediment must be quite high. Additionally, I believe it is quite possible that the recharge zone for this southern tip of the Edwards Aquifer may indeed reach well into the hilly areas of Mexico, well south of Val Verde county (since this is where the heaviest rains were concentrated).
Another question that will possibly remain unanswered relates to the source of the spring’s turbidity. I can’t help but believe that the silt and clay, which is abundant in the bedding-plane level at Goodenough, is the source of this turbidity. I observed a “lack” of these sediments on my excursions past the Laird Restriction. While the deeper source waters likely contained some suspended contaminants, I doubt that this water was inherently cloudy to the degree we witnessed at the cave’s entrance. An impossible dive into the Fire Hydrant Tunnel would be the only way to confirm this theory (which will most surely go unproven). It is important to keep in mind that all the conclusions related here are from a layperson’s perspective and could eventually be proven wrong, but still these are the only observations being made at this time.
To put this into perspective I have attempted to approximate the flow rate of Goodenough on the date we experienced these conditions. Without accurate cross-sectional survey data, I have to approximate the cave opening at 60 square feet (though it could possibly be 100 sf or more). Having experienced currents of varying degrees over the past 20+ years I believe that I can accurately gauge the flow at GE this past Saturday to be in excess of five knots. It was far in excess of any scooter ride I’ve ever taken and was more like the sensation experienced while being towed behind a boat. Using these approximations I could reasonably estimate the discharge to be in excess of 400 cf/s. This easily surpasses the measured discharge rate of Texas’ most prolific spring (Comal Spring) which has ranged from 300-350 cf/s in recent years. For comparison this is more than six times the average discharge rate of the combined Devil’s Cave system at Ginnie Springs. It is also slightly more discharge than the recorded average flow for Wakulla Springs (a much larger conduit than Goodenough).
While nobody expects this flow rate to continue, we still do not know how quickly it will subside. With lake levels a full 12 feet higher than our trip of a month ago, conventional wisdom would predict a subsidence of flow in the cave, but many forces are at work here and actual observations are the only accurate means of determining the true conditions. I hope to be able to make additional observations on-site in the next few weeks.
At this time I would request that we not cancel our next planned event (August 16/17), but it will be necessary to confirm that the system has once again normalized before carrying out our planned objectives. I am committed to checking conditions again before this date in order to better judge the possibility of holding a legitimate team event in August. Please do not abandon your plans for this August date until I am able to witness the trends in the spring firsthand.
Thanks go out to Rick, Mike, and Lovan for their invaluable help on this last trip. And thanks to Rio Trailers for “stocking” the necessary replacement springs for the boat trailer. I will surely be pleased when the National Park Service completes the planned pavement of Box Canyon Road.
Please see page three for a look at the rainfall accumulations from Hurricane Claudette. The “red dot” on the Mexico/US border roughly represents the location of Goodenough. The areas that show significant rain are all at higher elevations than the spring and are possible extensions of the aquifer’s recharge zone.
Chuck
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Addendum to Trip Report – 7/19/03
Submitted by Chuck Noe
Subsequent to my trip report of 7/19/03 I acquired an additional piece of information that may be of benefit in unraveling the mystery of Goodenough Springs.
I began utilizing the Sensus Pro data recorder on our 6/21/03 trip in an effort to systematically record information from my dives at GE. This device purportedly records the accurate depth, time, and ascent rates during a dive and is programmable for sampling intervals. I have set the sampling interval on my unit to be five seconds.
So far, on each GE dive, the device has stabilized at a constant temperature reading while inside the cave. While the exact reading may or may not be perfectly accurate, the relativity of this reading is important.
I first had the opportunity to check the temperature reading from this latest dive last night and found it very interesting that the cave temperature was a full 2 degrees F. lower than on the previous dives. The temperature was recorded to be 80 degrees as opposed to 82 degrees on my previous recordings.
Based on this finding I believe that it is possible, and quite likely, that the extra flow experienced on this date originated from a shallower water source. I also believe it is possible that this source is proximally closer to the spring. This could be one explanation for the unusually high turbidity of the water as well.
According to scientific data, the ground-water temperature at a depth of 30 to 60 feet generally exceeds the mean annual air temperature at a given location by 2.5 degrees F. Below these depths, the temperature increases about 1.8 degrees for every 100 feet of depth.
The mean annual temperature for the Del Rio area, as recorded by the National Weather Service, is 69.7 degrees F. We can therefore conclude that the ground temperature at 50 feet of depth is around 72 degrees. In order for the water to reach 82 degrees in temperature, it would have to originate at least 600 feet below ground (50 feet + 555 feet). It is also likely that due to the cooling of these waters while passing through shallower layers, the source water could be even deeper than 600 feet.
I believe it to be very significant that the temperature was significantly different on this past trip, during the high-flow period. But I do not believe that it is indicative of a shallower primary/permanent water source.
Chuck