FISHERIES REPORT of the LOWER COLORADO RIVER by The

Home , Mohave Valley, Palo Verde Valley, Parker Valley, Pyramid Canyon, Ringbolt Rapids, San Diego Aqueduct

FISHERIES REPORT OF THE LOWER COLORADO RIVER

The Fisheries Task Group Colorado River Great Basin Field Committee

September, 1951

Printing and Distribution by

Arizona Game and Fish Commission Phoenix, Arizona FISHERIES REPORT OF TBE LOWER COLORADO RIVER

The Fisheries Task Group Colorado River Great Basin Field Committee

INTRODUCTION

At the request of the Colorado River Great Basin Field Committee, a report on the fishery of the Lower Colorado River was prepared by Fisheries Task Group composed of fisheries biologists from the State fish and game departments of Nevada, Arizona and California, and a representative of the Fish and Wildlife Service. The report divides the Colorado River into seven sections, each river section being considered individually. The purpose of the report is to describe the present and potential aspects. of the fishery and of fishing recreation in the area, and to point the way for future fisheries research and management programs. However, some definite recommendations, based on the results of field surveys and research carried out to this date, have been made. The entire Colorado River area from Hoover Dam to the Mexican border has been covered by the field crews during the past year. The following individuals are accredited with undertaking the field survey End preparation of their compiled data as follows: Section I - Al Jonez, Nevada Fish and Game Commission and Jack Hemphill, Arizona Game and Fish Commission;

Section II - Al Jonez and Jack Hemphill; Section III - Richard D. Beland, California Division of Fish and Game; Section IV - Richard D. Beland; Section V - Richard D. Beland; Section VI - Gerald Duncan, U. S. Fish and Wildlife Service; Section VII - Richard A. Wagner, Arizona Game and Fish Commission. The Lower Colorado River Fishery is a diversified one and with minor exceptions one that is not being utilized to its fullest extent. As a result of serious drought conditions and the subsequent drying up of many lakes and reservoirs throughout the Southwest, the Lower Colorado River represents the last frontier for the ever increasing number of fresh water resident anglers. There has been, and no doubt will continue to be, an ever increasing recreational use made of the Lower Colorado River, and with wise management, the fishery will continue to provide good angling.

The fishes referred to in the report are as follows: *

Rainbow trout, Salmo gairdnerii, (Richardson) Largemouth black bass, Micropterus salmoides (Lapcepede) Smallmouth black bass, Micropterus dolomieu (Lacepede) Black crappie, Pomoxis nigro - mactifiEW-(Ee Sueur) White crappie, Pomoxir, -nnularis (Rafinesque) Bluegill, Lepomis macOodEgag,—(Rafinesque) Green sunfish, Lepomis cyanellus (Rafinesque) Redear sunfish, Lepomis microlophus (Gather) Brown bullhead, Ameriurus nebulosus (Le Sueur) Yellow bullhead, Ameriurus natalis (Le Sueur) Channel catfish, ICtalurus lacustris (Walbaum) Carp, Cyprinus cti5157(-Eanaeus) Bonytail, Gila robusta elegans, (Baird & Girard) Colorado squawfish, Ptychocheilus lUcius (Girard) Razorback sucker, Xyrauchen texanus (Abbott) Striped mullet, Mugil cephalTIT(EEnaeus) Ten Pounder, flops affinis (Began) Gambusia, Gambusia affinis (Baird & Girard)

The aquatic plants referred to in the report are as follows: **

Sago pondweed, Potamogetonlaectinatus Spiny naiad, Najas marina Widgeon grass, Ruppia maratima Horned pondweed, Zannichel iajm. Cattail, Typha domingensis Rush, Juncus torreyi Tale, Scirpus californicus Spike rush, Eleocharis parishii

SECTION I - MOHAVE LAKE

I. Physical Inventory This segment of the river is bordered on the north by Hoover Dam and on the south by Davis Dam. The reservoir itself is contained in Black and Eldorado Canyons, with the lower portion in Pyramid Canyon. High water elevation of the lake is 647 feet above sea level, and the operating level is 643 feet. During June and July, the lake level will drop (because of the requirements of the Mexican Water Treaty), and by August, will be approximately 627 feet. Lake Mohave is 67.5 miles long with a maximum width of four miles near Cottonwood Landing. All land use and concessions are under the jurisdiction of the

* Common and scientific names of fishes used in the sectional reports are taken from the American Fisheries Society Special Publication No. 1, A List of the Common and Scientific Names of the Better Known Fishes of the United States and Canada. **Aquatic plant names were taken fromFlowering Plants and Ferns of Arizona by Kearney and Peebles. National Park Service and Bureau of Reclamation. Fish and wildlife are administered by the states concerned.

The upper lake is a canyon-type lake, with sheer vertical rock sides broken occasionally by sandy washes that wind down from the surrounding mountains. Upper and lower Lake Mohave are arbitrarily separated at Emery's Landing in Eldorado Canyon. All roads leading into the lake follow these large washes in their general descent into the canyons. Near the center of the lake, long, sloping foothills extend back to the high mountain ranges on either side. These foothills contain many wide washes that have formed long fingers of water extending inland. These fingers have furnished excellent bass spawning areas during this fi year of inundation.

Lower Lake Mohave is characterized by rough, rocky shores with numerous inlets and coves. The lake is subject to strong winds at various seasons. In Summer, these winds are from the south and southwest; in winter, they are from the north. Occasional waves of oceanic proportions occur on the open portions of the lake during periods of strong winds. To date, this rough water is one of the main limiting factors to good fishing. The present policy of the Bureau of Reclamation is to operate the lake with a four foot maximum fluctuation. How- ever, emergency action in operational procedure may alter this policy.

II- Biological Inventory

The -species of fish present in Lake Mohave are: A. Game Fish:

1. Rainbow trout 2. Largemouth bass 3. Crappie 4. Channel catfish 5. Bluegill sunfish 6. Brown bullhead . Rough Fish:

1. Carp 2. ponytail 3. L,...mpback sucker 4. Colorado squawfish

C. Rainbow Trout

Most angling on Lake Mohave has been for rainbow trout, which comprises about 95 percent of the total catch. The game commissions of Nevada and Arizona maintain this trout population by plants of young fry and fingerling. Many millions of fry have been planted over the past several years ) and many age classes are present in the lake today. The record rainbow for 1950 weighed 18 pounds. Thus far, for 1951, an 18i pound rainbow caught near Willow Beach holds this season's record. From observations maa,. on the limited spawning beds a mile below Hoover Dam, it is known that many more of these large fish are present in the lake.

Asa result of observations over the past year, it is definitely known that trout can and will spawn in the upper portion of the lake. It was thought that rainbow did not spawn in the old river; but these recent observations prove beyond a doubt that rainbow did spawn in suitable areas as far down as Cotton- wood Landing. The fluctuation of water that occurred in the old river undodlt- edly damaged the redds of the rainbow. The deeper redds would not have been affected; these would have hatched. This conclusion was borne out by observations made among the spawning beds in and below the tailrace of Hoover Dam.

With the filling of Lake Mohave, and subsequent deepening of the water, spawning is now confined to the area above Ringbolt Rapids. There the current . has become slower and the water somewhat deeper. The increaied depth of the water should make the upper area of the lake a better spawning area in the future.

The growth rate of rainbow trout has decreased somewhat during the period of filling the lake. Now, however, growths of filamentous algae, widgeon grass, horned pondweed and sago pondweed are becoming established in shallow areas of the upper lake. With the establishment of aquatic vegetation, a proportionate increase of aquatic insect life is expected, along with the continuance of the fresh-water shrimp (Gammarus fasciatus) and snail (Limnaces E2.). This expected increase in available food should restore the previous growth rate.

D. Largemouth Black Bass:

A sizeable population of largemouth bass existed in the river area that has since been inundated to form lower Lake Mohave. This population had a very successful spawn in April and May, 1951, and promises to furnish some of the best bass fishing in the Southwest. This body of water is unique in that a sizeable population of trout and largemouth bass exist together. From studies complikted to date, it is believed that the shore areas of the lower lake will be excellent bass waters and the upper lake more suitable0 to trout. Water released from Hocver Dam has a constant temperature of 53 F. when released from

the lower level of0 the dam. (In 1951, the temperatures from the lower level have been near 56 F. because of the low level of Lake Mead.) This gives the0 upper ten miles of the lake cool water, even when the air temperature is 115 F.

in 0summer. The surface temperature of the lower lake is expected to rise to 80 to 85° F. in late August, driving the trout upstream or to greater depths. In winter, this lake will become almost uniform in temperature, allowing a mixing of trout and bass populations. The extent of this mixing of species is not known, but it is hoped that the trout will occupy the open lake waters and the bass the rocky shoreline. In early summer, the trout will either migrate upstream into cool waters or live in the lake depths near bottom.

Bass did not migrate into the cool upper lake water to any great extent In past years, unless. 68° P. water was being- discharged from the upper level of Hoover Dam. There. are two levels of discharge. It is highly desirable that only water from the lower level be discharged, to prevent migration of bass into the upper lake area where young trout live and are being planted.

Temperature studies to date indicate that a summer separation of species will occur between Cave Rapids and Emery's Landing in Eldorado Canyon. The Cold, heavier Water coming downstream is undershooting the warm surface layer. Down- stream currents will prevent this layer from forming above Cave Rapids. However, .strong southerly,winds may force this warm 0surface layer upstream to an undeter- mined-point. To date, this warmlayer (76 F.) has advanced but one_mile above Emery's Landing. The above findings indicate a permanent trout fishery from the vicinity of Emery's Landing upstream to Hoover Dam. Large trout will migrate downstream in the fall when the surface water cools and return upstream in. the winter to spawn. Migration of bass above Cave Rapids into the cold trout water is not anticipated so long as Hoover Dam continues to release water from the lower levels.

E. Crappie:.

Both black crappie and white crappie are present in limited numbers in Lake Mohave. In June 1951, a school of black crappie fry was observed and specimens were captured at the dock at Emery's Landing. Crappie are very rarelycaught in the lake at present, but will become more evident in the catch as their numbers increase. The initial brood stock was present in the river before formation of Lake Mohave, but they did not have suitable conditions to reproduce in great numbers due to the very swift current and low yearly temperature.

F. Channel Catfish:

Channel catfish are very rate, as witnessed by the fact that less than one specimen per month is caught in the lake. This species will probably increase in numbers with the formation of warmer waters in the lower lake.

G. Bluegill Sunfish:

Bluegill sunfish are not numerous at present, but should reach a sizeable population in the lower lake within a few years.

H. Brown Bullhead:

The brown bullhead is a rare catfish in Lake Mohave. One was taken on an experimental setline during 1950. That is the only broWn bullhead of which we have any record, but there must be more in the lake.

I. Carp:

Carp are abundant in the new lake and will undoubtedly become pestilent as the lake becomes stabilized. This species was introduced into the Colorado . River many years ago, but the date and source, of introduction is unknown. At present small carp appear to be one of the main sources of food for largemouth bass.

J. Bonytail:

The bonytail is one of the three fish native to the river. Although frequently caught by fishermen, it is not considered a sport fish. It is quite abundant, especially in the upper lake area but does not seem to compete seriously with the trout or bass. During its early life, the bonytail serves as a forage fish for largemouth bass.

K. Razorback Sucker:

The razorback sucker is another fish native to the Colorado River. It is very common, especially in the upper lake, and can be seen frequenting the -5- sand bar areas. It is not caught by anglers as frequently as is the bonytail, probably because of its habit of feeding on the:lake:h.tAtom.

L. Colorado Squawfith.:'

The Colorado sqUawfish is very rare; the laat one caught out of what is now Lake Mohave was reported in 1949. It is one of the largest of the minnow family and most of the squawfish caught in recent years weighed well over six pounds.

III. Present Use:

A. Access:

The present fisherman access to Lake Mohave is primarily limited to four points: Emery's Landing, Cottonwood Landing, Willow Beach and Katherine Wash.

. Emery's Landing:

Emery's Landing in Eldorado Canyon is at the end of Nevada High- way 6o, which joins U. S. Highway 95 a few miles from Boulder City. This entire route is paved. A choice of trout or bass fishing can be had from Ebery's Land- ing: upstream to trout waters, or downstream to the bass area. In winter, both bass and trout will be present in the immediate area.

Emery's Landing is equipped to furnish complete accommodations. Cabins, camping facilities, boats, motors, meals, fishing gear, mi fishing licenses are available.

. Cottonwood Landing:,

Cottonwood Landing is located at the end of a dirt road leading to the lake from Searchlight, Nevada. It is situated near the widest portion of the lake, and this area is furnishing excellent bass fishing the first year after formation of the lake. As the population increases from natural repro- duction, extremely good bass fishing is anticipated for the area from Cottonwood Landing to Davis Dam. Limited trout fishing is expected in the open portions of the lake in this area.

Cottonwood Landing is equipped to furnish tent houses, boats, motors, gro- aeries, fishing gear, and necessary licenses.

3. Willow Beach:

Willow Beach is located about 12 miles below Hoover Dam on the Arizona shore. The landing is accessible by a side road that leaves U. S. High- way 93 at a point 14 miles from Hoover Dam and 62 miles west of Kingman, Arizona. This side road leading from Highway 93 is four miles in length and has recently been surfaced. Willow Beach is within the lower end of Black Canyon and has a very perceptible current flowing by. This section is in the heaA of the trout waters. Very little bass fishing IS anticipated for this area; however, a few resident bass have been present for the past year. The water temperature is too -6- low to permit bass spawning in this area, thus an increase in numbers of that species is not expected.

Willow Beach is equipped to furnish cabins, camping facilities, boats, Motors, meals, fishing gear, and fishing licenses.

4. Katherine Wash:

A new landing in Katherine Wash is under consideration by the Park Service, and bids have been called for from interested concessionnaires. Katherine Wash is located three miles above Davis Dam on the Arizona shore. Advance planning calls for a paved road from Highway 68 to the landing. The Katherine Wash area has a good population of adult bass at present and the population has been greatly increased by an excellent spawn this season. This area should become the bass Paradise of Lake Mohave.

Cabins, camping facilities, boats, motors, meals, fishing gear, and fishing licenses will be available.

B. Number of Fishermen:

Fisherman use of Lake Mohave for 1950 was heavy, with 68,235 fishermen leaving the landings (willow Beach, Emery's Landing, and Cottonwood Landing). For the first five months of 1951, the total for these landings Was 47,554, as compared to 29,387 for the same period of 1950. This is an increase of 61 percent for 1951. With the stabilizing of this new reservoir and a corresponding increase in fish population, an even greater fisherman use can be expected.

C. Creel Census:

A creel census of 825 fishermen, over a period of six months, revealed a catch of 3.25 fish per fisherman. Of this catch, over 95 percent were rainbow trout. The average was 1.1 fish per hour, with an average weight of 1 pound per fish.

D. Percentage of Out-of-state Anglers:

From numerous counts of private motor vehicles parked at the various landings, an estimated 80 percent of the vehicles are from California. Arizona and Nevada contribute 15 percent together, and 5 percent are from various other states.

E. Use Permit:

The states of Arizona and Nevada have entered into an agreement Whereby a Colorado River Special'Use Permit is required of fishermen (who fish from a boat or other floating device) on Lake Mead, Lake Mohave, and the Colorado River below Davis Dam where it constitutes the Arizona-Nevada boundary. Thus, an Arizona fishing license must be accompanied by a Nevada Special Use Permit or a Nevada fishing license by an Arizona Special Use Permit. These permits cost $2.00 and are valid for one year.

-7- IV. Proposed Use: A. Recommendations for Development are:

1. Manage the upper section above Eldorado Canyon as a trout fishery and continue stocking with fry and fingerlings during the cool months.

2. Continue to close the spawning area below Hoover Dam during spawning season (December, January and February).

3. Plant rooted aquatic vegetation in the shallow areas to give cover for young fish in both trout and bass waters. Good beds of aquatic vegetation would greatly increase the food index for waterfowl as well as for fish.

4. Allow only those species now present in Lake Mohave to be used as live bait. Bluegill and crappie must be caught with hook and line to be used as live bait. Bass and trout should be entirely restricted from use as live bait. A real danger exists that the Utah Chub, (Gila atraria) may become established if Introduced into Lake Mohave. This species is very predacious upon the young of game fish and lips been known to completely destroy the sport fishery in some waters.

5. The States of Arizona and Nevada should obtain and distribute• additional stocks of fairy shrimp (Gammarus a.) in the event additional beds of aquatic vegetation are established.

6. Set up an egg-taking and hatching unit on Lake Mohave in the spawning area, to be used in restocking the lake.

7. The State and Federal agencies concerned with the area should continue biological studies of the fish life and related organisms. A knowledge of population movements, varied thermal areas, and food organism distribution is essential to management of this complex body of water with its mixed population of warm-water game fish and trout. All information to date has been gained under changing conditions of the lake while filling, and study must be continued to gain the true perspective after stability of the lake is reached. 8. Improve the roads paralleling Lake Mohave so they are suitable for public use. More access is needed to facilitate proper harvest of the fish crop.

SECTION II - DAVIS DAM TO NEEDLES

I. Physical Inventory: * This segment is 36 miles long and comprises the Mohave Valley. Airline distance from Davis Dam to Needles is approximately 32 miles. The eastern shore of the river is all in Arizona. Of the west bank, 18 miles lie in Nevada and 16 miles in California.

* The following description, A through E is taken from the Report of the Water- fowl Task Group of the Lower Colorado River Great Basin Field Committee.

-8- 1 A. Topography: Mohave Valley consists of a wide alluvial flood plain rimmed by desert mesas and mountains. The valley floor is very flat with a downstream gradient of about 1.5 ft. per mile. In microrelief, the flood plain shows numerous abandoned river channels, sloughs and shallow lake beds. There are approximately 70,000 acres in the flood. plain. The Colorado River, on leaving Davis Dam, flows between well defined banks for about 7 miles. In this stretch it is a narrow stream. Through the remainder of Mohave Valley, the river is generally broad and meandering with low banks and a number of.shifting. sand bars. Down to the tip of Nevada the area of flood,. plain is about equal on each side of the river, but from this point to Topock, the great bulk of the plain lies to the east of the river. At no point in this segment do the surrounding mountains closely approach the stream.

B. Vegetation:- This area is in the Lower Sonoran Life Zone. Vegetation is sparse except in the flood plain where water derived from the river is available. Here the plant growth varies with the ground water table which ranges from 0 to an estimated 30 ft. Tree associations consist mainly of willow and cottonwood and occupy generally, new and old channel banks. Mesquite, both honey pod and screwbean are .characteristic of the older abandoned channel beds. Newly abandoned channels, sand bars, etc., are taken over by brush consisting of arrowyeed, Baccharis and Tamarix (salt cedar). Along the flood plain margin, and extending into the mouths of entering desert washes are saltbush, mesquite and arrowweed, which are replaced by palo verde, catclaw, smoke trees and creosote bush as the ground water level recedes. The higher desert land is dominated by the creosote bush association described in Section 1. Along the river and sloughs, and dominating the valley floor from Topock to a point about two miles north of Needles, is a marshy area having considerable open water. Cattail, bulrushes and sedges interspersed with islands of willows comprise the principal vegetation. Drowned trees and brush occupy much of the inundated areas.

C. Access: Access to the river, as well as other recreational features of this segment, is fairly ample in quantity but generally poor in quality. North of Needles, a graded dirt road extends north to the Nevada line giving access to Wetmore Beach and Sedens Camp. This road averages about two miles distant from the river in California. Above the Nevada-California line the road touches the river at three points and eventually joins the paved road to Davis Dam. Nevada State Highway #77 branches from U. S. Highway #95, 13 airline miles west of Davis Dam and leads to thedam. By numerous graded and unimproved branchOs it affords access to theNevada shore at a number of places, among them Smee's Camp.

• -9- Arizona Highway 168 leads to Davis Dam from Kingman. Graded dirt roads closely parallel the river from the dam through Bullhead City to Fort Mohave. From this point to Five Mile Landing, approximately 16 miles, there is no vehicular access.

D. Climatic Data:

The region is characterized by low humidity, low precipitation, high temperatures and high light intensity. Annual0 evaporation is in excess of seven feet. Temperatures ranging from 18 to 125 F. have been reported. Average rainfall at Needles is 4.62 inches, which supports the desert vegetation but has no appreciable effect on riparian associations. Prevailing winds are from the north and south. In the spring and fall months, wind velocities are often high.

E. Present and Proposed River Controls:

While Hoover and Parker Dams are located outside this area, their control of. the river flaw has profoundly affected Section II.

Davis Dam is expected to smooth Out the effect of varying releases from Hoover Dam and to produce more uniform river flow in this section. Releases are to be made from Davis Dam from a depth sufficient to insure cold water suitable for trout. However, the unstable shifting sand bottom does not provide desirable trout habitat but is expected to undergo greater stabilization and form a rubble bottom as scouring of the bottom progresses.

II. Biological Inventory:

Species of Fish Present in Section II are as Follows:

A. Game Fish:

1. Rainbow trout 2. Largemouth black bass 3. Crappie 4. Channel catfish 5. Bluegill sunfish 6. Green sunfish 7. Brown bullhead

B. Rough Fish:

1. Carp 2. Bonytail 3. Razorback sucker 4. Colorado squawfish

The species of fish are the same for Section I and II, except a record of green sunfish is lacking from Section I.

In the upper portion of Section II between Davis Dam and Fort Mohave, rainbow trout are the most sought after game fish. Most individual trout are large and are two years old or more. This population is the result of plants of small

-10- fish made in the River below Hoover Dam before construction of Davis Dam. Some trout spawning is possible immediately below Davis Dam and more spawning area should be formed as the process of scouring progresses. Although no trout spawning activity has been observed in Section II, conditions for spawning similar to those of Section I are available.

Rainbow trout have been known to migrate in moderate numbers to the Needles- Topock swamp area. It is not known to what extent these migrants are lost when the water temperature rises in the swamp area. This condition has been changed somewhat by opening of the channel dredged through the swamp, thus forcing the river to flow in a defined channel without the consequent rise in temperature that was the case when the flow was spread over many miles of shallow swamp. This new development may induce more trout to migrate into Lake Havasu than has been the case in past years.

The upper portion of Section II has an abundant supply of small crustacea and insects. Plankton-crustaceans, and small insects are present in good numbers for young fish. However, the sterile sand bottom and general character of the river in this area are not conducive to the production of larger food organisms. Aquatic vegetation of the submerged type would greatly increase the food supply for larger fish.

It is yet to be determined to what degree the summer temperature of this Section will rise. The influence of Lake Mohave should not cause a rise in ' temperature of any significance to trout beyond the normal temperature before the dam was built. Assuming the above statement is correct, the upper portion of Section II should be managed as a trout fishery.

III. Present Use:

- Utilization of Section II as a fisheries resource is limited generally to the local population of Bullhead City, Arizona, and to Bureau of Reclamation personnel stationed near Davis Dam.

IV. Proposed Use:

A. Recommendations:

1. The area between Davis Dam and the southern tip of Nevada may support a trout fishery. Stabilization of water releases from the lower outlet valves will insure a water supply cold enough for trout. This section will probably remain in a latent state of development until the trout habitat improves. Should the tail race of Davis Dam be dredged, the area will be greatly improved due to removal of the swift, shallow areas of sterile sand. It is recommended that the abovearea be designated trout water.

2. Extensive development of Section II is not necessary at present due to extensive bass and trout areas in Lake Mohave. However, sufficient plants of trout fry are recommended to maintain the present population. 3. Several strips of land from the county road from Needles to the Nevada-California line to the river should be retained as public lands. This is to assure free public access to the river area above Needles.

Access on the Arizona side between Bullhead City and Fort Mohave should be improved, especially between Bullhead City and Mohave City.

SECTION III - NEEDLES TO PAREER DAM

I. Physical Inventory:

This section includes the area from Needles, California, to Parker Dam.

A. Water Regulation:

The river is confined for the most part, to a newly dredged channel and flows from Needles ten miles south to Topock where it enters Havasu Lake. The flow of the river is controlled by Davis Dam releases and Havasu Lake level by Parker Dam. The Topock Swamp water level is controlled by both river flow and Havasu Lake level.

Water levels of Havasu Lake i.e. Parker Dam Reservoir, play an important part in the success of the aquatic organisms inhabiting this large body of water. Except for drastic water level fluctuations in 1942, and for a short period in 1950, the variations in lake level have followed a set pattern Since the closure of Parker Dam in 1938. For the last seven years the maximum water level fluctuations have been six feet or less, with the exception of an 11 foot fluctuation in August of 1950. Generally, the reservoir is down four to six feet in January, builds up through the spring to the top of the dam and is drawn down again in the fall four to six feet to allow for any flash floods in the drainage between Davis Dam and Parker Dam.

Havasu Lake is used primarily as the diversion point for the Metropolitan Aqueduct, power and flood control. Water fluctuations are limited to less than ten feet by contract between the Metropolitan Water District and the Government.

B. Aquatic Habitat:

At the present time the river between Needles and Topock, ten miles downstream, flows across a wide alluvial valley forming a large swamp with many marginal lakes and sloughs. However, a newly dredged channel, due for completion in July of 1951, will carry the main flow of the river from Needles to Topock. The results will be a drastic change in habitat and some loss of desirable fishing waters.

The dredged channel will be lacking in submerged vegetation and aquatic plants. A shifting sand bottom will increase the waters turbidity and a levee on the east side will block off any marginal waters. For these reasons it is not expected to be a good producer of aquatic life.

-12- On the west side of the new Needles-Topock river channel two sloughs of 35 surface acres will enter the dredged channel. At Topock an opening in the levee will allow Havasu Lake to back up and flood approximately 61000 acres of the original Topock swamp. With the establishment of aquatic plants and settl- ing of the silt, these marginal waters will make an excellent habitat for warm- water fishes.

Havasu Lake, a 25,000 surface acre reservoir and the most important fishing water in this section, begins at Topock and extends 46 miles south to Parker Dam. The upper ten miles of the reservoir is confined to a rocky canyon. Here the river current is present and sand bars are formed creating small lakes confined between the abrupt canyon walls and the river. Heavy stands of tules develop on the sand bars and sago pondweed flourishes in the marginal lakes. The channel is 30 feet deep in this area. At a point called Blankenship Bend, the river current is less perceptible and a true lake begins to form. The remaining 32 miles consist of a long narrow reservoir with a highly irregular shoreline. The reservoir varies in width from one-half to one mile; however, at a point 20 miles below Topock, it reaches its greatest width of three miles when it floods the Chemehuevi Valley. The reservoir narrows and extends down to Parker Dam. The average depth is 22 feet; however, behind the dam it is 75 feet deep.

Both sides of the reservoir consist of an endless series of coves of variable size and depth.

Aqaatic vegetation, mostly cattails, sago pondweed and some spiny naiad are abundant in the Topock area and as far down into the reservoir as Blankenship Bend. The coves of the main body of the reservoir are, however, void of submerged aquatic vegetatiem for all practical purposes. Limited amounts of cattail and sago pondweed are found in the coves.

Riparian vegetation, primarily salt-cedar and arrowweed, is found in the coves but offers cover for fish life only at the high water level in the spring.

Until about 1946 submerged aquatics, mostly spiny naiad, flourished in the coves of Lake Havasu. This plant has since greatly decreased in abundance.

The brush and trees inundated at the time of dam closure have long since decayed, leaving only the dead main stems which offer little cover for aquatic organisms.

In several areas the cottonwood trees that formerly lined the river bank protrude above the surface in the center of the reservoir.

The bottom is composed of coarse sand and gravel on the open shore and silt over sand in the coves.

Although moderately rich in plankton, the reservoir is poor in invertebrate bottom fauna.

C. Water and Air Temperatures:

Water temperatures place the Topock Swamp and Havasu Lake in the warm- water fish classification. In the lake, high surface temperatures of 90° F. are

-13- recorded in July and lows of 45° F. in January. Observation to date indicates no 0thermocline is formed. Summer surface to bottom temperature differences are 14 F. in the lake at its widest point. As one proceeds down the reservoir, this temperature difference lessens until at the dam it is 4-5° F. due to mixing of the thermal layers.'

In the early part of 1952 it is anticipated that all the water released from Davis Dam will be from the subsurface. This will result in lower water temperatures in the river down to as far as Topock and may have a slight effect on the Havasu Lake water temperatures.

At the. present0 time maximum summer water temperature in the river at Needles is about 70 F. 0 Mean annual air temperature is approximately 72 F.

D. Structures Present and Permanency of Conditions: It is anticipated no new changes or structures will occur in this section in the immediate future other than the channel changes at Topock Swamp described above.

II. Biological Inventory: A. Fishes Present: The following fishes are known to be present in this section of the river: 1. Razorback sucker 2. Bonytail 3. Colorado SquawfiSh 4. Carp 5. Gambusia 6. Southern channel catfish 7. Yellow bullhead 8. Black bullhead 9. Black crappie 10. White crappie 11. Bluegill 12. Green sunfish 13. Largemouth black bass 14. Rainbow trout

B. Relative Abundrince: In TopockSwamp, bass and channel catfish are of equal importance as game fish. Black crappie provide good fishing near Topock for a short period in the winter. Bluegill are present in large numbers; however, they do not make up an important part of the catch due to the availability of the, more desirable bass and catfish.

Havasu Lake) One of the Most popular fishing waters in the Southwest, became well known because of the excellent largemouth bass angling it furnished. Although bass are still the most popular game fish, with 91 percent of the anglers fishing for them at least part of the time, bass fishing is not as productive as was the case for several years following the completion of Parker Dam. This leveling off from the post-impoundment peak is considered a normal situation, and it has many parallels in the histories of similar reservoirs. With the decline of the bass fishery the bluegill and black crappie have received increasing attention and pressure from the fishermen.

In the order of their importance, as reflected by the degree of fishing pressure on them are largemouth bass, bluegill, catfish, and black crappie.

A few rainbow trout have been reported caught in the Needles area. These are fish that have drifted down from stockings made above and are of minor importance to the sport fishery of this area.

Carp abound in this section, reaching their greatest abundance in the coves of Havasu Lake.

C. Other Formsof Aquatic Life:

Emory's soft-shelled turtle is present in limited numbers in the area; howeverithey provide-no iecreEtion. Bullfrogs provide some recreation in the Topock Swamp area.

III. Present Use:

A. Access:

Free public access to this section is adequate. Poor road conditions to the Site 6:concession on the Arizona side, and to the Road's Endoonceasion on the California side, limit access to these landings. All this area, from Parker Dam up to and including a major portion of the ,Needles-Topock Swamp, lies within the Havasu Lake National Wildlife Refuge operated by the U. S. Fish and Wildlife Service.

' Eight boat rental concessions under contract with the U. S. Fish and Wild- life Service are located in the area. Paved roads cross the river at Topock and Parker Dam, and dirt roads /each 'Havasu Lake boat concessions at five points well distributed throughout the length Of the lake.

B. Fishing Use:

The Havasu fishery is almost entirely a boat fishery, and small 12 to 16 foot boats are available at the five concessions Iodated on the lake. Bass and crappie are successfully taken by trolling or casting lures and live bait fishing from a boat along the shore line of the many coves. Bluegill and catfish are normally,taken by still-fishing with bait. Although high winds make boating on the lake hazardous on occasions, the fishery is available to a wide range of skilled and unskilled anglers.

Fishing is permitted throughout the year, but most of the angling is done from October to the first of June. Just as the temperature extremes on the upper -15- end of the scale limit fishing during the summer months the low air temperatures reduce the activity in January.

Excellent creel census and use data are available for this are, particularly for Havasu Lake.

The portion of Lake Havasu covered by this data includes that area from Parker Dam up the reservoir to a point about ten miles below Topock.

Fishing here is almost entirely from boats. Tabulation of concessionaire boat rental receipts and count of private boats indicate the Havasu fishery received a use in 1950 amounting to 24,851 man days of angling effort.

A one day a week creel census operated by the California Division of Fish and Game and the personnel of the Havasu Refuge over a nine month period during 1950 and 1951 is summarized as follows:

Number Hours Large- Anglers Fished mouth Channel Black Total Checked per Angler Bass Catfish Bluegill Crappie Fish 1,035 5.9 386 246 1,758 88 2,478

Catch per man day of angling effort 0.37 0.23 1.7 .08 2.39

Total fish removed from Lake Average weight of fish Total weight in pounds

Largemouth bass 9,264 1.15 pounds 10,653 Channel catfish 5,904 0.5 " 2,952 Bluegill 42,192 0.17 11 7,172 Black Crappie " 2 2 112 o.6 1,267 Total —37,47f 22,044

The lake receives a use of one angler day per acre per year. The harvest is 0.91 pounds of fish per acre per year. In general the use may be considered light and the lake's productivity low.

Periodic catch records, recorded during the first nine years of impoundment, 1938 to 1947, indicate that bass fishing during this period was considerably better than it is today.

One cause of the present day low catch per effort may be due to the increased number of anglers using the lake fishery. However, it is believed that the main cause is that the basic fertility of the water has depreciated. This is characterized by the almost complete failure of the aquatic weeds to develop from about 1947 to this date.

It is believed that this reduced fertility and absence of weed cover has resulted in less forage size bluegill and green sunfish being available for the development and growth of adult, catchable largemouth black bass and crappie. It is hoped that by introducing a new forage fish species, one that inhabits the center of the lake throughout most of its life, and which utilizes the plankton foods, the supply of forage fish for bass and crappie will be increased. The species now foremost in this consideration is the golden shiner minnow. Another measure designed to improve habitat conditions for the bass-bluegill combination is to increase the available cover. This will be attempted by either planting seeds of those aquatic species already present or by introducing new plant species.

If the above two plans fail to improve the quality of angling, the next alternative would be to introduce a completely new game and food fish combination.

Because 91 percent of the anglers made their greatest effort to capture the largemouth bass, the statistics for the catfish, bluegill and crappie do not give a true picture of their availability nor the potential productivity of the lake. If a greater effort were made to capture these less popular species, the catch- per-angler and the total harvest would be greater.

The use in the Topock Swamp area is estimated at approximately 6,000 angler days'-use per year> Anglers here made a greater use of the channel catfish and crappie. Fishing in general for bass, catfish and crappie is of a better quality than in Havasu Lake.

IV. Proposed Use:

. Type of Fishery:

Except for the possible introductions of new warm-water fishes', this fishery will remain as it is today primarily a largemouth bass fishery with bluegill, catfish and crappie of lesser importance.

With the development of V- anticipated trout stocking program below Davis Dam, some of these fish may drift down into the dredged channel below Needles. However, this Needles area is not expected to develop into a productive trout water.

B. Present Use in Relation to Potential Use:

As in the other sections, Havasu Lake and the Topock Swamp area have experienced a year-to-year increase in fishing pressure.

It is believed that the bluegill, catfish and crappie populations of Havasu Lake are capable of being exploited to a much greater extent. The bass population however, appears to be utilized to its maximum production capacity under present conditions.

With the decline of the Havasu largemouth black bass fishery, it is not known if this area will continue to show a year-to-year increase in fishing use.

C. Recommendations for Development:

1. Consistent with the management practices in other waters, stocking of warm-water fishes already present in the river is not recommended.

-17- 2. It is recommended that during the period.Marth 15th to August 30th, the Havasu Lake water level not be drawn down more than one foot. This is to protect the bass spawning and bluegill.

To maintain good growths of submerged aquatic plants water fluctuations should be limited to less than two feet. However, from November to February, lowering the water an additional two feet should not be injurious.

3. It is desirable that the golden shiner or other recommended types of forage fish be introduced into Havasu Lake as forage for bass and crappie and as a buffer for the young game fishes.

4. It is recommended that access to the Arizona side of Havasu Lake be improved, both to the Site 6 and Bill Williams Arm area. 5. It is recommended that the study program be continued and that it be directed along the following lines:

a. The present study of the Lake Havasu fishery in all its aspec+c: be continued. The primary effort be directed toward improving the largemouth bass and crappie fishing and if this should fail to try introducing new game fish species.

b. The practicability of introducing a new submerged aquatic weed or increasing the amounts of those already present in the coves of Havasu Lake be analyzed. This is to provide cover for small fishes and increase the available food supply.

c. The practicability of constructing brush shelters in the Havasu Lake coves be analyzed.

SECTION IV. - PARKER DAM TO HEADGATE ROCK DAM

I. Physical Inventory:

This section includes that portion of the river from Parker Dam to Headgate Rock Dam, an irrigation diversion structure 15 miles downstream.

A. Water Regulation:

The river flow is regulated by Parker Dam, an 85 foot diversion, flood control and power structure. In general, during the past seven years, the volume of flow has varied from a high in February of about 20,000 c.f.s., to a low of about 11,000 c.f.s. and followed by an increase in the fall to about 18,000 c.f.s.

Daily water fluctuations vary considerably throughout the year. Typical is the water release from Parker Dam during April of 1950. In that month the volume of flow in c.f.s. varied a maximum of 5,000, from a high of 19,500 to a low of 14,500. The day to day fluctuations ran from 500 to 3,500.

-18- In the future the volume of river flow will follow the same general pattern of a wide seasonal fluctuation and a variable daily and weekly fluctuation.

B. Watershed and Immediate Terrain:

The watershed is of the Desert type, Lower Sonoran Life Zone. For 12 miles below Parker Dam the river winds through a narrow rocky canyon and is generally well-confined between stabilized banks, there being little area of meandering where the river spreads out over sandbars. The last three miles the river flows through the north end of Parker Valley.

Riparian vegetation is abundant and consists primarily of willow and cottonwood trees, salt-cedar and arrowweed.

C. Aquatic Habitat:

With exception of a few small marginal bays of slack water formed by sandbars, and a reservoir of 50 surface acres behind Headgate Rock Dam, the waters of this section are all lotic in nature.

The river varies in width from 600 to 800 feet except at that area behind Headgate Rock Dam, where it spreads to a width of approximately 2,000 feet.

There are many deep holes of 30 feet or more; however, most of the river in this section varies from 8 to 15 feet in depth.

The water released through the Parker Dam power turbines is free of silt. The slight turbidity of the river section, much less than other river sections, is due to sand picked up by the action of the current on the river bottom, and plankton.

Except for the marginal waters, which have an overlay of silt and debris, the bottom is covered with sand.

One of the most differentiating characteristics of this area, as compared to other sections of the Lower Colorado River, is the abundance of sago pondweed. Large beds of this rooted aquatic parallel the shore through much of this river section.

Rooted aquatic vegetation along much of the shore provides excellent cover for aquatic organisms.

D. Water and Air Temperatures:

Parker Dam Reservoir has only a slight cooling effect on the water of this section. Water temperatures of 84° F. are recorded in August and 18ws of ° ° April, 70 F. in 49 F. 0in January. Water temperatures0 normally read 65 F. i8 May, 80 F. in June, and return to 75 F. in September and 60 F. in November. 0 Mean annual air temperature is approximately 72 F.

E. Structures Present and Permanency of Conditions:

Parker Dam at the upstream end of this section acts as a barrier to fish. It is not known if Headgate Rock Dam is also a barrier to fish movement

-19- Upstream

No new structures or dredging operations are planned for this area. II. Biological Inventory:

A. Fishes Present and Relative Abundance:

All fish listed in Section III are present in this area.

In addition, redear sunfish are present and smallmouth bass have been planted in the area, although it is not known if the smallmouth have established themselves.

This river section supports a much greater fish population than is found In other portions of the river. This greater ,productivity is due primarily to less turbid water and a more stable bottom and shore line. Seining and observations indicate that large numbers of largemouth bass, hluegill and crappie are present; however, the fishery is supported largely by the channel catfish -and bluegills.

Black crappie and largemouth bass provide only limited angling.

Green sunfish are present in less abundance than the bluegill and serve primarily as a forage species.

The native fishes and bullhead are a rarity. Carp are abundant. B. Other Forms of Aquatic Life:

Emory's soft-shelled turtle and the bullfrog are present in limited numbers in the area. III. Present Use:

A. Access:

Although much of the river bank has been fenced off, free public access in this river section is ample at this time. A paved road parallels the river between the two dams on the California side. An unimproved dirt road extends from Parker north and parallel to the river for ten miles and south from the Arizona side of Parker Dam for three miles.

B. Fishing Use:

This is one of the most heavily utilized poirtions of the Colorado Riven

LArge numbers of trailers are found in the nUmerOus trailer camps during the winterseason of October to May. A greater part of these people are retired couples who make heavy use of the river fishery.

-20- No extensive fishing use data and Only limited creel check information are available for this section.

On November 18, 1950, 150 house trailers were present on the banks of this river section and 120 small boats present on its waters. In addition, 40 forms of permanent habitation plus the small Government housing project for the Parker Dam employees are found along this 15 miles of river.

Fishing use is estimated at from 15,000 to 20,000 angler days during 1950. Unlike other portions of the Colorado River, much of this use is by bank fishermen.

The quality of angling may be generally regav-1.ed as good for bluegill, fair for channel catfish and poor for largemouth blapk'bass and black crappie.

The following creel census data portrays the fishery.

Number of Total Hours Largemouth Channel Location Date Anglers Fished Bass Catfish Bluegill Colorado River 10-15.50 18 74 39 59 Parker Dam to 10-107.50 9 29 3 8 58 Headgate Rock 10727-50 13 39 1 25 18 Dam 11-18-50 8 46 9 f f1 11-19-50 11 32 ------1- 120 59 220 4 gg 255 Catch per effort is 1.3 channel catfish per angler day and 4.3 bluegill per angler day.

The bluegill and catfish are the mainstay of this river fishery. The bluegill can be taken at many points from the shore; especially popular is bank-fishing immediately below the tail races of the Parker Dam power house. No great skill or elaborate equipment is required for their capture. It is believed this species could be utilized to a greater degree.

The channel catfish is caught equally well from shore or boat. , Angling for this species in this section can only be considered fair. Like the bluegill, no great skill is required for successfully taking the catfish. Thus these two species are popular game fishes.

The largemoutl-. bass and black crappie do not provide much sport in this river section.

IV. Proposed Use:

A. Type of Fishery:

Because conditions for existence of the cold-water forms of fishes are not present in this river section, this fishery will remain as it is; a warm- water fishery with bluegill and catfish predominate in the catch and bass and crappie of secondary importance. However, if introductions of new game fish species, such as the smallmouth bass, are successful, the fishery may change for the better.

-21- B. Present Use in Relation to Potential Use:

No extensive studies of the fishery in this section of the river have been made; therefore, the reasons for the poor largemouth bass and crappie fishing, and only fair catfish angling, have not been determined.

There are, however, some indications that over-fishing is not the cause for the low angler success ratio.

IT is known that this river section is capable of supporting a large fish population. With the successful introduction of new game fish species, such as thL smallmouth bass, this area may prove to be a much more desirable fishing location.

At the present time the bluegill, and to a lesser extent the catfish, are capable of receiving a greater use.

C. Recommendations for Development:

1. Consistent with the management practices in other waters, stocking of warm-water fishes already present in the river is not recommended.

2. It is recommended that during the largemouth bass spawning season, March 15 to May 15, and the bluegill spawning season, June 1 to August 30, the water level fluctuations be minimized to a verticle rise and fall of less than two feet, consistent with other usages of the river.

3. As practiced in other waters, the construction of anchored brush shelters along the river bank is recommended.

4. It is recommended that at strategic locations along the river on both the California and Arizona side, preferably near popular fishing sites, the land lying between the road and river be retained as public lands to assure free access for camping and bank-fishermen, and free launching sites for private boats. Also that the road from Parker, Arizona, to FarW,Dam be completed on the Arizona side.

5. It is recommended that the study program be continued and that it be directed along the following lines:

a. A study of the channel catfish and largemouth bass as they exist in the river.

b. Ascertain the desirability of:

(1) Introducing a new forage fish species (2) Introducing a new game fish species (3) Expanding a brush shelter program in the river.

-22- SECTION V. - BEADGATE ROCK DAM TO PALO VERDE DRAIN

I. Physical Inventory:

This section includes that portion of the river from Headgate Rock Dam, to the outlet of the Palo Verde Drain, 81 miles downstream.

A. Water Regulation:

The river flow is regulated at Parker Dam and is the same as that described for Section IV except for diversions of 500 c.f.s. at Headgate Rock Dam and boo c.f.s. at the Palo Verde Weir,

B. Watershed and Immediate Terrain:

The watershed is of the Desert Type, Lower Sonoran Life Zone. The river of this section meanders through a wide alluvial valley with the town of Parker, Arizona, on its northern boundary and Palo Verde, California, on its southern boundary. There are extensive acreages of irrigated farm lands below Parker and in the Palo Verde Valley. Where not cultivated, there are extensive areas of this river bottom land overgrown with cottonwood and willow trees and heavy stands of brush: mostly salt-cedar, arrowweed and mesquite.

C. Aquatic Habitat:

In relation to other sections of the Lower Colorado River, this section is notably lacking in lentic waters. With the exception of five major oxbow lakes and sloughs and a limited number of small, semipermanent marginal areas of slack water, all waters of this section are confined to the river and are lotic, moving water, in nature.

The river meanders considerably throughout this section varying in width, depth and velocity. The gradient throughout the section is about one and one-half feet per mile. Where the river is confined between stabilized banks, it is about boo feet in width with depths of 8 to 20 feet. Through much of the area in question, approximately one-third, the river spreads out over sandbars forming numerous semi-permanent islands. In these areas there are wide expanses of shallow water where the river flows over the sandbars. The river bottom continually shifts, forming new channels and islands. Water erosion on the river bank periodically fells trees and brush which assist in stabilizing the banks and forming shelter for the aquatic or-Pnism. The water is slightly turbid, due primarily to small particles of sand. This turbidity varies depending on the direction and velocity of the current and increases slightly as one goes downstream. The river bottom consists almost entirely of sand except for small areas of silt over sand in the marginal slack waters.

The biotic conditions of the river, excluding the five major lentic waters, are characterized by the nearly total absence of rooted aquatic plants and invertebrate bottom fauna. Limited stands of cattail and bulrush are found on the sandbars and small amounts of sago pondweed are found in the marginal waters.

-23- In addition to the river there are five areas of lentic water. One mile below Headgate Rock Dam on the California side there is a lake of approximately 20 surface acres, which has a maximum depth of 10 feet and wide shoa) areas of shallow water. It contains extensive beds of sago pondweed and some ,3piny naiad. A wide, shallow channel connects this lake with the river. A paved road parallels this lake. Eighteen miles downstream from the above-described lake is Alligator Slough and Lost Lake, an oxbow of the river formed in 1942. This lake, horseshoe in shape, is 58 acres in surface area with maximum depths of 12 feet. Because the sand and silt settle out, the water is not turbid, 5 p.p.m. (platinum wire), and moderate stands of aquatic plants develop, mostly sago pondweed. A large fishing camp, accessible by road one-half mile off highway 95, is located here.

Fifty-nine miles dovistream from Headgate Rock Dam, on the California side, is a small lake known as tass Lake. This body of 20 surface acres of lentic water has a narrow connection to the river and is accessible by boat from the river only during high water, a flow of 14,000 c.f.s. or more. Maximum depths of 13 feet and wide areas of shallow water supporting a luxuriant growth of pondweed are found here. A dirt road leads to the upper end of this lake. Due to heavy stands of brush surrounding this lake and the absence of any forms of habitation on its shore, this water is not heavily used for fishing purposes.

Located 76 miles downstream from Headgate Rock Dam, near the end of this river section, is a river-connected lake of approximately 15 surface acres called Miller's Pond. No forms of habitation are found on its shores. The immediate terrain consists of heavy stands of brush. An unimproved road three miles out of Palo Verde reaches this lake. This water is little used for fishing purposes. Palo Verde Drain enters the river 81 miles downstream from Headgate Rock Dam. This is a seminatural slough which carries the Palo Verde Valley irrigation drainage water back to the river. That section of the drain navigable by boat extends for 12 miles up through the Palo Verde Valley from the moeh of the drain. Except for a one mile portion of the drain located at the town of 7Pa10 Verde, six miles up from the mouth, the drain is a narrow, 40-60 feet, tule lined, fairly rapid and turbid, 150 p.p.m. (platinum wire) body of water. At the town of Palo Verde the drain widens out, 100-150 feet, for a distance of one mile. The depth varies from four to seven feet and good beds of aquatic plants, mostly coontail, are present. Present on the shores of the drain at Palo Verde are 77 permanent forms of habitation. Eighty-nine boats, 12-14 foot rowboats and outboards, were counted tied to the shore in this area. Five boat concessions maintaining 45 rental boats are in business here. Palo Verde Drain at one time was a popular fishing center for largemouth black bass. However, due to the increased activity of the irrigation district within recent years, and the resultant increased turbidity of the waters, the bass fishing has drastically declined. The present fishery in the drain is dependent on the channel catfish. In addition to these waters some fishing is had in the extensive system of irrigation ditches and canals found in the Palo Verde and Parker irrigation districts. -24- D. Water and Air Temperatures:

Water temperatures recorded0 at Palo Verde0 Weir, 11 miles north of Blithe, are as follows: maximum 90 F., minimum 52 F., January average 52 F., and August average 87° F.

0 Mean annual air temperature is approximately 72 F.

These water temperatures place this fishery in the warm-water classification. Suitable conditions for the cold-water forms of fishes, such as trout, are not present.

E. Structures Present and Permanency of Conditions:

There are no dams present in this section. It is not known if Headgate Rock Dam at the upper end of this section is a barrier to fish. A rock weir used for irrigation diversion, which raises the water five feet, is found 11 miles north of Blythe. As this weir either halts or slows the migration of fishes, it is one of the most popular and productive fishing areas in this river section.

Dredging operations to be undertaken by the Bureau of Reclamation will change the river considerably in the lower portion of this section. A new channel will be dredged commencing at Taylor's Ferry and extending for 15 miles down Cibola Valley to Cibola Lake on the Arizona side of the river. This will result in draining seven miles of the river in this section, draining Miller's Pond, estimated to lower the water level two to three feet and • increase the velocity of the current in Palo Verde Slough. The fishery will be a total loss in those areas drained and may have a detrimental effect on the Palo Verde Slough fishery.

The river as it flows in the newly-dredged channel will not be productive of fish life.

Improvements and changes at the Palo Verde Weir are contemplated. The effect on fish life is not known.

In general no new structures or major dredging operations, other than those described above, are planned for this river section. However, it is said by persons in authoritative positions that eventually all the river will be either reservoirs or dredged channels. It may be said that diversion weirs and non-fluctuating reservoirs are a benefit to fish life; whereas river channel dredging and the maintenance of a successful river fishery for warm-water fishes are incompatible.

II. Biological Inventory:

A. Fishes Present and Relative Abundance:

The fishes present in this area are the same as listed in Section III.

In addition, the following minnows are being propagated in ponds near Blythe and Ehrenberg: golden shiner, Notemi onusonus shiner, Notropis lutrensis and fathead confertus.

-25- As in river sections above, the razorback sucker, bonytail and squawfish are present in such limited numbers in this section of the river as to be considered of no importance to the fishery either as forage or game fish.

The channel catfish is the mainstay of the sport fishery in this section of the Colorado River. klthough the channel catfish is found in all the lakes and marginal waters, it reaches its greatest abundance and size in the river and Palo Verde Slough.

The largemouth bass and bluegill are most successful in the lentic waters. They are also found, to a much lesser degree, in those parts of the river where cover and slack waters are formed by felled or submerged trees and brush.

The crappies green sunfish and yellow bullhead are not found in abundance and do not constitute an important part of the river fishery. However, at the river fishing hole below Palo Verde Weir, the black crappie is frequently taken. The yellow bullhead occasionally appears in the catches made at Palo Verde Slough.

Carp are found in abundance and exist under all conditions.

B. Other Forms of Aquatic Life:

Emory!s soft-shelled turtle is found in all waters of this section but reaches ita greatestr abundance in the sandbar areas of the river. There Is no commerCial exploitatiOn of this resource and but few anglers, mostly residents onAheriverl- make-vse of them. The flesh of this turtle is an excellent food. Specimens of 20 pounds or more are common.

Bullfrogs are distributed throughout the river but are found in abundance only in the Parker and Palo Verde Irrigation districts. They are especially numerous in Palo Verde Slough and here receive heavy use.

III. Present Use:

A. Access:

Although free public access is limited along much of the river due to dense stands of brush and no-trespassing signs, access through numerous fishing camps and selected points, at which the public roads adjoin the river, is available.

Highway 72 crosses the river at Harp, and roads paralleling-he river on both sides provide access to Headgate Rock Dem. Indian reservation lands extend from Parker to Ehrenberg on the Arizona side and approximately 23 miles south of Harp on the California side. There is little access and use in this area.

At a point 18 miles below Headgate Rock Dam on the California side, Highway 95 joins the river and parallels it to Palo Verde Weir. Numerous unimproved roads lead from the highway to fishing camps on the river. From Palo Verde Weir to Blythe access is poor. At Blythe Highway 60-70 bridges -26- the RIVER. FROM Blythe to the end of the section the river is accessible at several points where county roads reach the river. A paved road reaches Palo Verde 19 miles south of Blythe. From here an unimproved road extends eight miles to a fishing camp on the drain near its connection with the river.

On the Arizona side the access is very limited from Ehrenberg south. FROM PARKER SOUTH TO 3 miles above Ehrenberg the land on the Arizona side is Colorado River Indian Reservation. Free public access is denied in this area.

B. Fishing Use:

Except at several points where angling pressure is intense, fishing use on this section of the river may be considered light.

The greatest use of the river fishing is made by anglers from distant centers of large populations, primarily the Metropolitan area of Southern California.

Although angling is to be had throughout the year under present regulations, the fishery is used to any appreciable degree only during the period of early October to the middle of May. High summer air temperatures make June to September angling unpleasant. Local anglers use the fishery throughout the year; however, their numbers are limited.

No complete catch records or creel censuses were made for this area; however, use data can be derived from spot angler counts and interviews with boat rental concessionaires.

It is estimated the river fishery receives an angling pressure from boat fishermen of 7,390 man days of angling effort. Shore angling is approximated at 4,500 man days. Two-thirds of this shore use is concentrated in the one-quarter mile of shore line immediately below the Palo Verde Weir. Total river use amounts to 11,890 man days of angling effort, or 146 angler days per year per river mile.

In addition to the river use, Lost Lake ;and Alligator Slough provide 4,200 man days use from boat fishermen and a considerable use from bank anglers.

Palo Verde Slough is fished to the extent of 7,300 angler days from boats and receives some shore use.

No extensive studies have been undertaken in this area relative to the abundance of fishes and quality of angling. However, catch records which are kept on a voluntary basis by operators of boat liveries give a general picture of the nature of the fishery.

-27- Numbers Hours fished Channel Largemouth Location Date Anglers per Angler Catfish Bass Weir boat October-50 160 4.7 449 53 rental November-50 105 4.8 239 9 Because of the extensive area of the rivet section in question, the difficulty of access through Much of its length, and the generally light fishing pressure, it is believed that the angler's catch has little influence on the channel catfish population and that this population could adequately support a much greater angling pressure.

The method of capture of the channel catfish is invariably bottom fishing with bait from either shore or boat. Good angling is had all year except for a short period in the winter.

Although most of the channel catfish caught by anglers range in size from 10 to 14 inches, fish weighing 10 to 15 pounds are common and specimens of 22 pounds are reported.

No great skill or elaborate equipment is required to capture this species. It is considered an excellent food fish. For these reasons-, it is a popular and desirable game fish.

The largemouth bass, the species second in importance, in the river fishery, is found inhabiting those areas of the river where submerged vegetation provides' cover.

Although no population studies or creel checks have been made, it is believed that this species is present only in limited numbers. Angling is at its best during the summer and fill: The local anglers make the most use of this fish.

Considerable skill and equipment is necessary to navigate the river, for successful capture of the largemouth bass. Shore fishing for this 'species is not productive.

Bluegill and black crappie fishing in the river is not good. Only at a few selected points, such as the hole below Palo Verde Weir are they found in numbers. Here, they provide fair fishing.

Lost Lake and the other three lentic waters described differ from the river in that the largemouth bass and bluegill are of equal importance to the catfish.

Of these four waters only Lost Lake is heavily used and is producing a maximum number of fish consistent with size and fertility.

The Palo Verde Slough fishery is almost entirely dependent'on the channel catfish. The high turbidity of this water precludes successful largemouth bass and bluegill fishing. As the records indicate, angling is fair to good.

-28-

Number of Channel Largemouth Location Date Anglers Catfish Bass

West's Boat Rental-Palo 0ctober-50 289 788 10 Verde Slough November-50 362 642 28 Catch per effort is 2.7 and 1.9 channel catfish per angler day.

Because of the limited amount of water available and heavy use, it is believed that the Palo Verde Slough fishery is being fully utilized.

IV. Proposed Use:

A. Type of Fishery: With the exception of the reduced productivity of some river areas due to dredging operations and the possible introductions of new warm- water fishes, this fishery will remain as it is today: primarily a channel catfish fishery with largemouth bass and bluegill of secondary importance.

B. Present Use in Relation to Potential Use: The river and some of the lentic waters are capable of much greater utilization. The fishery of Lost Lake, Alligator and Palo Verde Slough are receiving near maximum use.

C. Recommendations for Development:

1. Consistent with the mangement practices in other waters, stocking of warm-water fish already present in the river is not recommended.

3. The construction of anchored brush shelters along the river bank is recommended.

4. It is recommended that free public access be assured along the river by retaining as public lands key sectionsof the river bank, and numerous narrow strips of land from Highway 95 laterally out from the river in that area from the southern boundary of the Indian Reservation south to Blythe on the California side. A similar type of access in the area from Ehrenberg south to Cibola Lake on the Arizona side with public camp grounds is also recommended. In addition, the roads of the Palo Verde Valley adjoining the river should be kept open to public access.

5. It is recommended that agreement with the Colorado River Indian Reservation Agency be obtained, assuring free access to the river in -those areas where the indian reservation and the river adjoin.

6. It is recommended that the research program be continued and that it be directed along the following lines:

-29- a. A study of the channel catfish and largemouth bass as they exist in the river.

b. Atcertain the desirability of:

(1) Introducing new forage fish species (2) Introducing new game fish species (3) Initiate a brush shelter program in the river.

SECTION VI- PALO VERDE DRAIN TO IMPERIAL DAM I. Physical Inventory:

A. General: This section extends from the mouth of the Palo Verde Drain to the Imperial Dam a river distance of 49 miles. As a result of the Pilot Cut dredging operation, the Palo Verde Drain empties into the bed of the old river channel, flows three miles down to the connection of the Pilot Cut, which carries the full flow of the river, and again flows into the river channel.

In the upper portion of Section VI the Colorado River flows through Cibola Valley, in Arkzona, and Palo Verde Valley in California, an extensive bottomland area overgrown with willow, salt cedar, mesquite, and arrowweed, until it reaches the mouth of Cibola Lake, 11 miles below the mouth of the Palo Verde Drain. This 11 miles of river is slightly more turbid than above the Palo Verde Drain. Felled and submerged brush and tree cover is present along most of the shore and there is little river meandering. Although some bulrush and cattail are found along the river bank, submerged aquatics are very scarce. The next 13.5 miles of river flows through a neck formed by rocky desert terrain in both California and Arizona. Very little bottom land exists here but a few small backwater lakes are present. The river is bordered in pert by cane and cattail but in many places desert terrain extends to the river's edge.

In the following 8.5 miles, bottomland area is more extensive and larger backwater lakes bordering the river channel are present. Cane and cattail are in abundance along the channel and in favorable locations willow is found along the river banks. For the next 4 miles the river flows east and is bordered by the Trigo Mountains in Arizona and the Chocolate Mountains in California. The sloughs entering Fergeson Lake, which is one of a chain of small backwater lakes on the California side, leave the main channel of the river in this four mile river section.

-30- The next 12.3 mile stretch of the river, down to Imperial Dam, is the portion of SectiOn VI whichreceivesthe •bulk of the fishing pressure. In this portion of the Section there are larger areas of open water, including Fergeson Lake in California and Martinez Lake in Arizona. Extensive growths of cattail anxIcane interspaced:With: bulrush forM the 'bulk of the vegetation in this area.

B. Water Regulation:

At present there is only:one - water .control structure within Sec- tion VI. This is Imperial Dam, 18 Miles northeast of Yuma, Arizona. This dam is'a diversion dam which diverts much of the water of the Colorado River to the Imperial Valley in California via the All American Canal; and to the. Yuma area in Arizona Via the Gila Canal.. Biweekly sluicing activity (an effort to keep silt from building up immediately behind the dam and curtail- ing dam operations) lowers the level of the river at the dam approximately six feet and at Castle Tome Landing, six miles upstream, about four inches. This operation takes approximately four hours or less and has no apparent ill effect on fish life in these areas. Upon completion of the Welton-Mohawk Canal-, additional water will be diverted at Imperial Dam to reclaimed desert landt hear Welton Arizona• Cotpletion of this canal is expected in early: 1952.

The Bureau of Reclamation has begun preliminary work on the Cibola Dredging Project. This project consists of dredging a channel from Taylor's Ferry (11 miles upstream from the Palo Verde Drain) 15 miles south down Cibola Valley to Cibola lake, Arizona. It viii carry the entire flow of the river. With this channel cut through, probably all of Davis and Three., Finger Lakes and most of Cibola Lake willipe drained.

C. Water Area:

Listed below are approximate areas of the more important backwater lakes in Section VI.

Name (not official) Area (surf. acres) Location Fergeson 570 California Martinez 785 Arizona, Ridden 15 Arizona Clear 15 Arizona: Blue 25 California Government 10 California Island 115 Arizona Taylor ' 250 California Adobe 600 Arizona Draper 45 California Walker 20 California Cibola 1500 Arizona Three-Finger :45 California Davis 45 California Total :: 4445 .. Most, if not all, of these "lakes" are silting in The rate at which silt is being deposited depends primarily upon the size of the inlet.

-31- Some of this open water which has become shallower due to silting has been taken over by cane and cattail and has the appearance of an emergent marsh.

The majority of the backwater lakes in Section VI are relatively clear. One exception to this is Cibola Lake, which at times is very turbid, possibly due to wind action and shallowness. The main channel of the Colorado is, of course, turbid due to its silt load.

Watershed and Immediate Terrain:

Section VI lies in the Lower Sonoran Life Zone and the desert areas adjacent to the river are characterized by creosote bush, brittle bush, palo verde, ironwood, several species of cacti and desert annual weeds plus grasses. In the dryer areas of the bottomlands, arrowweed, mesquite and willow are present. As the soils become more moist, salt cedar becomes abundant. Willow and mesquite are present as well as aquatics, depending upon the degree of soil moisture and depth of water. Cane, cattail, bulrush and bur- weed are in abundance in the marsh areas and such aquatics as pondweed and naiad are common on the bottoms of the "lakes" where environmental factors conducive to their growth are present. In some areas of this section where the aquatics are abundant, they are believed important to the survival of young fish.

E. Water and Air Temperatures:

Water temperatures place this section in the warm water fish - 0 ° classification. Water temperatures of 82, F to SO F are common throughout the summer with a minimum of 45° F to 50 F in winter. The mean annual air temperature is approximately 72° F.

II. Biological Inventory:

A. Fish Present:

Fish known to be present in Section VI include the following: largemouth black bass, black crappie, bluegill, green sunfish, channel 'catfish, yellow bullhead, carp, razorback sucker, and gambusia.

Other fishes which may be present are bonytail, Colorado squawfish, desert killifish, mullet and white crappie. The marginal lake areas adjoining the river offer good bass and bluegill fishing and fair crappie and catfish fishing. The main channel of the river offers good catfish fishing and limited bass fishing. The largemouth black bass is by far the most 'important and most utilized game fish in these waters. It is of interest to note that in the past year larger catches of black crappie have been made than in previous years.

B. Other Forms of Aquatic Life:

Emory's sat-shell turtle and the bullfrog are present but are not utilized to any great extent. There is a season on bullfrogs in both Arizona and California.

-32- Crayfish are present in this section of the river but their abundance has not been determined. It is believed that. they may constitute part of the diet of the bass and possibly other fishes in this area.

II. Present Use:

Davis Lake and Three-finger Lake are accessible from the town of Palo Verde via 21 miles of unimproved road. There is one camp (Mitchell's) on the river near Davis Lake, where 11 boats are available for rent. Five of these boats are at the camp and six are at Davis Lake.

In 1950, Davis Lake was fished only during the spring, as the water was too low during the remainder of the year. There was an estimated 200 man days of fishing use on the lake in 1950.

Three-finger Lake was also inaccessible during the fall of 1950 and there was an estimated 300 man days fishing on this lake in that year. There is one rental boat on this lake.

There are two camps (Walter's and Stewart's) approximately one half mile below Three-finger Lake.- Two rental boats are available at Walter's Camp and four at Stewart's Camp.

At the lower end of Cibola Lake is a small concession where 15 boats and a few outboard motors are available for rent. At this location there is also a small cafe (catering mainly to waterfowl hunters) and a few tent cabins. Cibola Lake is accessible from Ehrenberg over 45 miles of unimproved road. An estimated 600 man days of-fishing was done on Cibola Lake in 1950.

Approximately 1000 man days fishing was done on the river between the mouth of the Palo Verde Drain and the lower end of Cibola Lake in 1950.

At Picacho, California, an old mining community, 18.5 miles upstream from Imperial Dam, there are several permanent houses and about 25 people reside here in the winter months. Very few remain during the summer. There is no concession or boat rental establishment here but there is a possibility that one might find a boat to rent.

Approximately 14 private boats belonging to residents of Imperial Valley are docked at Picacho and about 500 angler days fishing per year are done in the backwater lakes and sloughs and along the river in this vicinity. Picacho is reached from Winterhaven, California, which is 25 miles to the south, over an unimproved dirt road, which at times is in such bad condition that only four-wheel drive equipment can travel over it.

At Castle Dome Landing, Arizona, six miles upstream from Imperial Dam, is located the Calizona Sportsclub concession, which operates through a permit issued by the U. S. Fish and Wildlife Service, Twenty boats and several outboard motors are available for rent here. There is a restaurant, store, and 10 rental cabins located at this concession. A good airplane landing strip is located within walking distance of the store and cafe. The Calizona Sportsclub concession is reached from Yuma, Arizona, via Highway 95 (32 miles). The first 6 miles consists of newly paved road, while the

-33- remaining portion is dirt road. In the vicinity of the Calizona concession are several private cabins, and on March 31, 1951 there were 72 private boats in this vicinity.

An estimated 30,000 people used the Castle Dome Landing area in 1950 as a means of access to the Colorado River for fishing purposes. Many persons come from Phoenix and Ajo in Arizona as well as San Diego and the Imperial Valley in California. The majority of the anglers are local people from Yuma, Arizona and surrounding farm area, or from Winterhaven, California and the Bard Valley.

On the Arizona side of Imperial Dam is a small concession, also operated by the Calizona Sportsclub. There are seven rental boats and three rental outboard motors available to fishermen at this location. In addition, a small store is present. This Imperial Dam concession is 18 miles north of Yuma, Arizona via the Bard Valley, California; or approximately 25 miles north of Yuma via Highway 95. There are 10 or 12 private boats docked at - this concession which are in the custody of the concessionaire. It is estimated that 1740 people used this concession for fishing purposes during 1950.

There is also a good boat launching site on the California side of Imperial Dam and an estimated 1200 anglers used this as a means of access to the river.

Approximately 95 percent of the fishing in Section VI is done from boats. There is limited bank fishing in the vicinity of Martinez Lake as well as a few places between Castle Dome Landing and Yuma Wash in Arizona. The total use of this section, as measured in man days of angling effort, is approximately 35,540 angler days. This represents an angling intensity of about seven man days of angling per surface acre per year on the 4,445 acres of lakes. The 49 miles of river available are but little utilized. Approximately 90 percent of this fishing use was in those marginal waters between Imperial Dam and Castle Dome Landing, Fergeson Lake, and Martinez Lake. Considering the nature of the fishery, this use may be regarded as light and the waters capable of supporting greater angling utilization.

A creel census operated on a one day a week basis from February to June, 1951 at Castle Dome Landing by personnel of the U. S. Fish and Wild- life Service indicates the nature and quality of the fishery in this section. The creel census data are summarized as follows:

No. of Anglers Hours Fished Fish Caught Checked per Angler LM Bass Bluegill B. Crappie C Catfish 311.14. 4.03 413 49 15 46

An average of 2.63 hours were required to catch each fish, while the average total number of 1.52 fish was caught per angler per day. It is estimated that 90 percent of the anglers fished either all or the majority of the time for largemouth black bass, which is by far the most popular species. The catch of bass was 1.2 per angler-day. This may be considered as fair fishing success for this species, taking into account the nature and use of the water.

-34- The creel census statistics do not accurately picture the relative abundance of the other species listed in the catch as little effort was made to harvest them. Bluegill and channel catfish are present in fairly large numbers and angling for them is good. Bluegill, however, are small in slog. the average catch consisting of fish from 5i to 6 inches. The average channel catfish caught varies from 3/4 to l. pounds, although specimens weighing from 10 to 15 pounds are common. Black crappie were present in significant numbers for the first time during the spring of 1951. Little use was made of this fish during the census period as the anglers were not aware of its abundance or methods of capture. Should the present trend continue,. this entire are, particularly Fergeson and Martinez Lakes, may develop into a highly desirable crappie fishery.

In considering the fishing use, water area and wuality, plus angler's success in general, it may be said that the largemouth black bass is being adequately harvested, whereas, the bluegill, channel catfish and black crappie are capable of supporting greater exploitation.

IV. Proposed Use:

A. General:

Except for the possible introductions of new warm-water game fish species, this fishery will remain much as it is today: primarily a largemouth black bass fishery with bluegill, catfish and crappie of lesser importance'.

B. Recommendations for Development:

1. Consistent with the management practices in other waters, stocking of warm-water fishes already present in the river is not recommended.

2. Public access routes into this area are nil. One major access route should be constructed from Ehrenberg south to Cibola with dirt roads leading from this construction to the river at key points. A public camping ground for anglers in this area should also be established. Improve- ment of the access route from Martinez Lake north is also recommended.

3. It is recommended that the access via the California side to the Fergeson Lake area be developed.

4. It is further recommended that the research program be continued with efforts directed along the following lines:

a. A general study of the fishery in this section. b. An analysis of the desirability of introducing new forage and/or warm-water game fishes in the Lower Colorado River Drainage.

-35- SECTION VII - IMPERIAL DAM TO THE INTERNATIONAL BORDER

Section VI14 Which is approximately 4o miles long, is-diVidedinta the following two Zones: (1) Imperial Dam to.SagunaDaM,.and ( ) Laguna Dam taTthe International Border.

I & II. Physical and Biological Inventory: :: Water regulations governing Udage'in this section are controlled by the U. S. Bureau of Reclamation; and when applicable by the Government' Of Mexico. Most of the water is used for irrigation

Zone 1, about 4 miles long andamiles wide -ia composed of a shifting river channel through which sterile sand bars are constantly being carried toward the Gulf of California.' A few dead-end sloughs and side-Areas are found which join the river through Stall channels.

The immediate drainage area of the zone is over 30 square miles, but with the annual average precipitation less than five inches, there is little runoff.

Zone 2 is composed of 35 miles of shifting river channel thtoUgh a flood plain. Where the river meanders, it produces a wide to one-half mile) shallow area, which usually has no definite channel. Through the summer the riVet is at times too shallow to navigate by boat. The turbid waters carry tremendous amounts of sand but contain little'dissolved.organic . mattar which-can be utiliZed'by aquatic vegetation: With physical conditions so ad- verse to aquatic life, the effect upon the fishery is inhibitory.

The annual air temperatures for, this section fluctuate from 32° F to 128° F, with an average of 72° F. Water temperatures range from 45° F to 90°'F.:

This area contains a warm water fishery. The most prevalent fish species are tarp,- channel catfish and striped Mullet. Channel catfish support the' sport fishery it this section.. - However, some largemouth blacktatai'bluegill', black crappie and yellow bullhead fishing is done: Green sunfish and razorback suckers' are also known to be present.. The fish fauna Of this' section of the river differs primarily' from :the• other sections in that striped 'mullet are present in fairly large numbers; likewise a few tenpounder (Elope) are occasionally taken.

The aquatic plants of the section are primarily emergent types consisting of cattail, reed,'bulrush,:pondweed,. spikerush', spiny naiad, widgeon grass and sedge. Other plants found in or slang the watetaoUrtes are'cottan- wood, willow, salt cedar, arrowweed, salt grass, salt bush, inkweek, mes9uite, chufa and others usuilly'clasted'as typical desert plants

The Water quality of thia'section'isvety. pOiDt; waste water from the irrigation district contains some fertilizers, but this is offset by the increased amount of dissolved salts. The city of Yuma, Arizona, allows raw domestic sewage and waste to enter the river. The coliform content of the river below this point has increased over 1500 times as most probable number over the upper area. The effect upon the fishery is not conclusive; however, -36- it does create a serious public :halth .problemt

Structures present are: Imperial Dam (a definite block to migrating FISH), LAGUNA Dam (a partial block), Alamo Canal (no hindrance), Yuma Irriga- tion CANAL (a partial block), and-Morrelos, Dam (a partial block). . It is not economically feasible to screen the main parts of this diversion system.

USUALLY at eight o'clock 'on Thursday: mornings some OF the GATES are opened at each end of Laguna Dam. This causes a four foot head of water to come cascading down the apillways. Only moments before this, water was coming over the dam and many fish were at its base. With the sudden drop of the water level, many fish are stranded among the rocks and in very, shallow pools • at the base of the dam. Although over 50 percent by Weight of the fish destroyed by this means are rough fish, (Primarily carp and striped mullet)there are still a large number of game fish (mostly channel catfish) lost.

During the spring and early summer months large channel catfish, some specimens over 25 pounds in weight which are moving through the area during their spawning period, are reported stranded among the rocks below Laguna Dam. The writer has observed on different occasions interested persons returning over 3,000 catfish from six to eight inches in length to suitable water. Some catfish observed weighed over eight pounds.

Tinder such short observations it is difficult to tell what effect, if any, this stranding has on the fishery. Steps are being taken to achieve the flushing of the silting basin more slowly. When this is done, the number of stranded fish is reduced.

There are no nel.vstructures proposed for this section of the river.

Laguna Lake and the surrounding marshland is over 1500 aeres in'extent. The Yuma Boat Club has launching facilities here and it is one of the most popular spots of the area Angling is for bass, bluegill and catfish. The bullfrog fishery is also utilized to a limited extent.

Mittry Lake, above Laguna Dam, is about 2,000 .surface acres in area with an average depth of eight feet. It is highly turbid with no direct connection with the Colorado,River. Seepage prevents this lake from going dry. A small amount of flushing water from the Gila Canal also enters this water body. Due tõ the small.i.olume, this arrangement is highly unsatisfactory for longevity because of the evaporation rate, which at times exceeds 10 feet per year. With this tremendbus loss of water, the saltsin solution normal to the river are carried from the river into the lake. Evaporation of the water leaves these salts behind and the lake concentration continues to increase.

Total salts contained in Mittry Lake are from 10,000 ppm to a minimum of approximately 600. ppm, which the main river contains in the spring of the year. Sodium and calcium chlorides compose approximately 27 percent of the total dissolved material.: blaring certain periods, the flooding river has flushed the lake. The total dissolved salts in this body of water at .times are far beyond the probable, tolerances offish and other aquatic life.

Water right investigations are now underway to determine water needs.

-37- This data it is hoped, will enable interested and affected parties to negotiate an agreement which will provide sufficient water to flush the lake and maintain lake water quality on a par with the river. In this case, it will again support a warm-water fishery.

Haughtelin Lake, located in Zone 2 about 3.1; miles above Yuma, Arizona, on the California side, is the most important fishing lake in the area. This water has a maximum depth of 30 feet. Water is supplied by seepage from the river proper. Haughtelin Lake proper has 58 surface acres and contains a minimum of 348 acre feet. Fair bass fishing and good bluegill fishing is available here.

The sand bottomed pool formed by Morrelos Dam has a variable water level. There are small finger inlets projecting around the periphery. A few of these inlets contain bulrush and cattail in limited amounts. The water quality is impaired here by the raw sewage from the city of Yuma. At the present time its effect upon the fishery is not known. Catfish provide 'the most fishing but carp are also utilized.

III. Present Use:

A. Access:

Public access in this area is good. Hard surfaced roads trans- verse the area as well as graveled and graded roads. The most distant point of the section is not over 25 miles from a town.

B. Utilization:

In the summer, most of the fishing is done at night for catfish. "Poachers" congregate at Laguna Dam on the California side, when it is flushed, to pick up catfish, mullet and carp (preferred in that order). The area is more fully utilized during the winter months. Most of the fishermen are local to the area. A very small percentage are from the other areas of the states concerned. During the winter season as many as 60 house trailers and camps may be found in the area between Laguna and Imperial Dams on the California side.

C. Fishing Pressure:

Few counts of fishing use have been made. However,,it is known that moderate to heavy use is made of the fishing waters at Morrelos Dam, Haughtelin Lake, Laguna Dam and the marginal waters behind Laguna Dam on the California side. This river section as a whole, however, may be considered as receiving light use.

D. Type of Fishery:

This area contains a warm-water fishery. Fishing is done both from shore and from boats, with bait fishing being predominant. in the old Alamo Canal and Haughtelin Lake a few fishermen use plugs, but this type of angler is in the minority. Economics appear to dictate the amount of gear to which each angler has access. Otherwise, the canepole angler appears as skilled and successful as the "bait casting" angler.

-38- IV. Proposed Use:

A. Recommendations for Development:

1. Consistent with the management practices in other waters, stocking of warm-water fishes already present in the river is not recommended.

2. Laguna Dam flushing techniques should be studied and modified if possible to benefit the fishery.

3. Mittry Lake should be developed to its full potential by ob- taining a proper waterflow. A planting program to establish aquatic plants is also recommended.

4. Further study should be made of the desirability of introducing new forage fish species. 5. It is also recommended that the study program be continued and that it be directed along the following lines:

a. General study of the fishery. b. The practicability of introducing new submerged aquatics for food cover. c. The practicability of employing various management techniques as influenced by their costs.

CONCLUSIONS AND RECOMMENDATIONS

I. The sport fishery of the Lower Colorado River represents a very valuable recreational resource for the ever increasing number of anglers residing in the Southwest.

II. The Lower Colorado River fishery, with minor exceptions, is not being utilized to its fullest extent.

III. The management of fisheries in waters so large and complex as those under consideration must depend upon the continuous gathering and analysis of data concerning these fish populations, and the effect upon them of harvesting. Therefore, the research program, initiated by the three states adjoining the river in cooperation with federal agencies', should be continued in order to effectively manage the fishery. This research program should be directed along the following lines:

A. Develop the most efficient trout stocking program possible for the cold water areas.

B. Continue study of the warm-water fishery in all its aspects.

-39- C. Ascertain the desirability of introducing new game and forage fish species.

D. Determine methods of increasing the amount of submerged aquatic plants in both cold and warm-water areas.

IV. Control the introduction of undesirable fishes. This is to be accom- plished primarily by the control of the use of live bait fishes.

V. Work in cooperation with other agencies to obtain water regulation bene- ficial to fish life, consistent with other usages of the river waters. Gener- ally speaking the construction of dams has aided rather than hindered the development of the Colorado River sport fisheries. On the other hand, various channel dredging projects or extreme water fluctuations may prove very detrimental.

VI. Retain as public lands access routes to fishing areas and sections of the river bank as outlined in this report. This is to assure the public free access to the fishing waters of the Lower Colorado River in the future when public recreational use will undoubtedly be much greater.

VII. Stocking of warm-water fishes already present in the river is not recommended, since it serves no useful purpose. VIIL Efforts should be continued to provide for uniform regulation and administration of the Colorado River fishery as a single unit by all three states. An example of this need is the lack of a reciprocal fishing license arrangement between Arizona and California. IX. The formation of a permanent body to study and recommend actions for the effective management and utilization of the fishery is desirable. Such a body should consist of representatives from each of the three states and federal agencies concerned. This system has, proven successful in the management and administration of other interstate fisheries, such as the Columbia River ‚fishery or the Pacific Coast marine fisheries.

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