Could the Lower Salt River near Phoenix become a blue ribbon trout fishery to rival Lee’s Ferry or the San Juan?
That question arose in the early ‘90s during the last wet years Arizona experienced. There was so much wet stuff in the watershed that the Salt River Project had to release water into the Lower Salt year round from Stewart Mountain Dam that backs up Saguaro Lake.
With those high year-round flows combining with the high nutrient and insect forage levels in the Salt, the trout stocked into the river experienced phenomenal growth rates and anglers were routinely catching 18-inch-plus, hard-fighting rainbows. The possibilities captured a lot of imaginations.
Angler groups and Arizona Game and Fish Department fisheries biologists began asking themselves, "Have we been missing an opportunity here for a Blue Ribbon trout fishery in the desert just a short drive from downtown Phoenix?"
But there was also another question biologists needed to answer - what is the impact of the current flow and trout stocking regime on native fishes, and what might be the impact on those natives from increased flows should they be implemented in the future?
In partnership with the Bureau of Reclamation, Game and Fish launched a research study on the Lower Salt to answer these and other questions. The study was primarily aimed at the native fish question, but sought some answers - or at least some more biological information - on the year-round trout fishery question. That initial study has is finished.
The answer on the year-round trout fishery was not definitive, but the biological information and speculation rendered the possibility as a bleak one. The problem is water quality: the high water temperatures and low dissolved oxygen content during the summer would make trout survival, and therefore carryover, marginal at best.
Research biologist Scott Bryan said the summer water temperatures at even 1,200 cubic-feet-per-second flows get up to around 77 degrees. For rainbow trout, the department has to be extremely careful when stocking fish in water that is over 70 degrees. Temperatures as high as 77 degrees can be lethal to stocked trout.
Then there is the dissolved oxygen problem. Trout do best when the dissolved oxygen in the water is higher. Three milligrams per liter is about the minimum for trout survival. As water temperatures rise, even greater amounts of dissolved oxygen can be necessary for trout. During the summer, the Lower Salt gets down to about two milligrams per liter, or lower.
"Based on those two water quality factors, our biological assumption is that trout will not over-summer on the Salt. Some may survive, especially in the deeper pools, but most would not," Bryan pointed out.
However, he added, this is by no means a definitive answer. To truly answer the question, further research would be needed. Expensive research; the investigation would have to entail doing costly experimental flows.
There was also another question to be answered relative to the trout fishery; would it be possible to have increased winter flows to bolster the seasonal trout stocking and fishing on the Lower Salt?
During the winter, releases from Steward Mountain Dam are typically lowered to about 8 cfs (except in very wet years when upstream reservoirs are full). At that point, the trout stocking shifts downstream toward Granite Reef Dam. The winter trout fishery is sustained from Verde River inflows to the Salt River, miles downstream from Stewart Mountain Dam. Those Verde River flows are enough to sustain a popular put-and-take trout fishery during winter from where the Verde River enters the Salt to the Diversion Dam a few miles downstream.
The question everyone wanted answered is what might happen if the winter flows from Stewart Mountain Dam were increased to a minimum flow regime of 50 cfs? The study results provide a good news, bad news scenario.
The good news is that native fish would probably not be severely impacted by increased flows, although the current flow regime probably gives them the habitat-use edge over the nonnative rainbows, bass, sunfish and catfish (sometimes even walleye) that are in the river.
The bad news is the possible costs (and money source) for implementing such a practice.
The annual cost for delivering enough water to sustain 50-cfs flows in winter would be around $90,000 (that would actually be the cost of lost opportunity for generating hydroelectric power). The cost for the additional trout would be around $11,000 annually. The cost of implementing increased law enforcement and creel surveys along that stretch of river in winter would be around $8,500 each year. But because of the native fish question, the cost of monitoring the effect of the increased flows on the natives would be around $100,000 per year.
That brings in a fiscal reality check: where would the money come from?
"We don’t have that type of money available in Game and Fish coffers without impacting other programs," explained Fisheries Branch Chief Larry Riley.
A special use fee for that area is possible has been suggested by some but if kept reasonable, it would not generate sufficient income to support the whole operation. Collecting and enforcing such a fee could also be challenging.
While having a blue ribbon winter fishery along the Salt for the entire stretch doesn’t look financially feasible, there is an alternative to have at least a small stretch of blue ribbon fishing.
Mesa Regional Fisheries Program Manager Jim Warnecke has offered an alternative; stocking larger rainbow trout in the first 1.3 miles downstream from Stewart Mountain Dam during the spring flows from April through June. This would entail having special catch-and-release regulations for that stretch, or possibly allowing a one fish bag limit, with the fish being more than 16 inches long.
"The estimated cost of the larger trout would be $5,500 annually and it would provide some blue ribbon trout fishing close to Phoenix. Access for that stretch of river is not good right now, but it could be improved through volunteer labor building trails. It’s certainly something to consider," Warnecke said.
But this initial research project also prompted another intriguing question: Is there a future possibility of creating a popular fishery for a native sport-fish -- the bonytail chub?
Roundtail chub are hard-fighting fish that anglers sometimes catch along the Lower Salt, and more routinely catch along upper stretches of the Verde River. Could roundtails be raised in the hatchery for a put-and-take native fishery? Would anglers actually participate in large enough numbers to make such a fishery possible?
While the latest research didn’t provide all the answers biologists need, or even a lot of good news, it did set the stage for possible future studies (if funding sources can be found), and sparked some other intriguing questions and possibilities for the future. The book is not closed on the Lower Salt potentials.