he Bureau of Reclamation has proposed installing a Temperature Control Device (tcd) on Glen Canyon Dam, to warm the water sufficiently during certain months of the year (May through September) to help the endangered humpback chub, other native fish and the blue-ribbon trout fishery below the dam. This didn¹t just come out of thin air; the idea of warming the water has been batted around for a while now. In the Glen Canyon Dam Environmental Impact Statement (eis) the u.s. Fish and Wildlife Service issued what¹s known as a jeopardy opinion about the humpback chub and BuRec was obligated to respond. The opinion stated that the chub were in jeopardy from continued operations of the dam, and that the temperature of the water was a limiting factor in their survival. Although the chub spawn in warm tributaries (mostly in the lcr), when the young fish hit cold water as they leave the spawning grounds, they are either killed outright or so physically disabled by the cold that they are an easy catch for predatory non-native fish. Sounds pretty simple. Warm the water a little (about seven degrees celsius leaving the dam) when the chub need it and they¹ll flourish, right? Well, maybe. Then again, maybe not.

There are some problems with this proposal, not the least of which is that the Bureau did only an Environmental Assessment (ea) on the proposal, instead of a full-blown eis, which requires a lot more research and time to complete. What¹s more, their ea was done without the aid of much substantial biological and ecological science. And if you read the ea‹something I wouldn¹t wish on anyone‹some glaring gaps in our knowledge become quite clear, gaps that make us here at gcrg a little nervous about just jumping in with yet another major change to a system that has seen plenty of changes already.

When Glen Canyon Dam was put in, three very important physical processes were stopped: sediment flow, wide temperature fluctuations and seasonal floods. No one knows which of these three factors is the most important for the native fish in the river, but it is very likely that all three are so interconnected that singling one out for a simplified solution is not the answer, and may do more harm than good. For example:

• While warming the water may indeed help the native fish, by BuRec¹s own admission, it will most likely make conditions more favorable for voracious predators such as channel catfish and brown trout, and for other non-native species that compete with the natives for food and spawning areas.
• Warming the water may also increase the possibility of diseases such as whirling disease to enter the system, and again by BuRec¹s own admission, Asian tape worm, which already exists in the lcr, would likely increase after warming the water.
• We do not know if warming the water in this fashion is a reversible process. In other words, if we begin to see decline in the native fish populations, can we just turn the cold water back on again and everything will recover‹or have we pushed a delicate balance too far over the edge?
• What are the impacts and consequences of warming up the food base in the river? We know very little about the aquatic food base and the needs of the native fish in the system. Again, are we going to tip a delicate balance too far over the edge to recover if we do this?
• The alternative chosen for a tcd was one of the cheapest and simplest to install, but it lacks a great deal in flexibility. Should we be looking at a different design that will allow for finer detail in range of temperatures during different seasons?
• The proposed design for the tcd draws water from higher in the reservoir, a process that may not be possible to enact in low-water years. What about the consequences of putting this whole thing in motion and then not being able to use it in critical years due to low reservoir levels? Do we set up the native fish to need warmer water and then not be able to give it to them?

These are just a few of the concerns we had in reading the Bureau¹s ea. In the long run, it is clear that we know far too little about the intricacies and complexities of this ecosystem, dam-controlled or not, to be carelessly turning knobs and changing parameters. The aquatic and riparian ecosystem of the Colorado River through Grand Canyon are an interconnected web which defy oversimplification. Perhaps we do need to warm the water to help the native species of the Colorado River. We feel that this should be determined through a carefully conducted eis that considers this and all other alternatives. If it is determined that temperature modifications are needed, we must look very carefully at the proper device and technique to achieve this. Cost effectiveness and simplicity of design may work for bureaucracy, but ecosystems rarely notice those details.

Whether you agree that Glen Canyon Dam should be decommissioned immediately or left to go naturally (as it will), the beast is with us now and we need to manage its behavior as carefully and mindfully and knowledgeably as possible to protect the ecosystem it has created. Going back to the days before the dam is not possible anymore. There are non-native species, diseases and toxic chemicals throughout the system that have changed it for the foreseeable future. We cannot go back but we can move forward. We can and must begin to effectively and as far as possible restore natural processes, native biodiversity and natural systems and patterns to this river. Only in that way can we let the patient heal herself and once again become a true, living river.

Christa