THE PARIA RIVER MOUTH 

AS AN EXPERIMENTAL HUMPBACK CHUB REARING SITE: 

A PRESENTATION TO THE GLEN CANYON DAM 

TECHNICAL WORK GROUP 

Lawrence E. Stevens 

Grand Canyon Wildlands Council

Prior to completion of Glen Canyon Dam, the mouth of the Paria River and 

adjacent Colorado River hosted a large population of humpback chub. Early 

observations by Mormon residents, and AGFD fisheries studies from 1964-1968, 

documented the abundant presence of HBC in and around the Paria River confluence. 

That reach of the Colorado River mainstream is remarkably similar to that near the Little 

Colorado River confluence, with abundant backwaters and eddies, and much 

opportunity for near-shore warming, particularly if the mainstream is warmed by low 

reservoir levels or by a TCD. The Paria River HBC population has been extirpated, the 

loss of which is the primary example of range reduction for this endangered species in 

Grand Canyon. Interviews with early Lees Ferry residents reveal that HBC ran up the 

Paria River at least as far as the Mormon dam (ca. 5 km upstream from the confluence), 

and HBC were particularly abundant in the Paria River mouth when the mainstream 

Colorado River flooded (May-July). Other native fish then or since reported in the lower 

Paria River included razorback sucker, Colorado pikeminnow, flannelmouth sucker, and 

speckled dacce. The Paria River sometimes is too warm in mid-summer to support 

native fish above the mouth area, except in springs in the narrows, so the large ponded 

mouth of the Paria River likely served as the spawning and rearing area for HBC in predam time. 

Glen Canyon Dam eliminated seasonal ponding and habitat availability at the 

Paria River mouth; however, a gravel mine was used for roadbed materials by the 

Mormon homesteaders and, since by the National Park Service. The gravel mine lies 

immediately upstream of the Paria River mouth on the Paria River delta. 

 In this presentation, I discuss development of an experimental rearing facility in 

these gravel mines. Such a facility would allow the Glen Canyon Dam AMP to learn 

about in situ HBC and other native fish propagation, and eventually to restore HBC to its 

former range in the vicinity of the Paria River. This plan calls for the construction of 

several, small gated ponds, to be used for experimental and rearing facilities. Water for 

the ponds would be derived from the Paria River, and mainstream water would be used 

to cool the ponds in mid-summer. Following successful pilot studies with flannelmouth 

suckers, larval HBC would be placed into the Paria ponds, and reared and released into 

the mainstream.. Unlike all other sites proposed for second HBC populations, the Paria 

River site is a practical site for such studies, as it has easy to access by road. The 

ponds would provide opportunities to test ideas about TCD and other issues facing 

native fish in Grand Canyon. 

These ponds would be temporary, experimental facilities, and may be inundated 

under flows >45,000 cfs; therefore, they should be maintained and operated as such, 

without long-term expectations or insured production each year. Such ponds would be 

easy and inexpensive to construct, and will be easily replaced if inundated by high 

flows. 

I present the pros and cons of the use of ponds, and a draft design and schedule 

for pond construction.