Diamond Valley Lake

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Metropolitan Water District of Southern California

October 3, 2003 is the Grand Opening

Contact            Lynda Poggenphol   909.652.3027  "Diamond Valley Lake Representative"
July 23, 2003
The Latest Info
  • This reservoir is larger than Lake Havasu and took 4 years to fill.
  • This reservoir will hold as much water as combining Castaic Lake, Lake Mathews, Pyramid Lake, Lake Perris and Lake Skinner into one.


  • Between Temecula and Hemet off Hwy. 79 at Newport Rd. in the Domenigoni/Diamond valleys, which is four miles southwest of the city of Hemet.
  • The visitor center is on Newport Rd. at the east side of the lake. Take Hwy. 79 to the new Domenigoni Hwy. Go east 7 miles to State St., turn right, go about 1 mile to Newport Rd., turn right.
  • Project cost: $1.9 billion


  • Almost doubles Southern California's surface storage capacity.
  • Secures six months of emergency storage in the event of a major earthquake.
  • Provides additional water supplies for drought protection and peak summer needs.

Storage Capacity:

  • 800,000 acre-feet or 269 billion gallons of water.
  • One acre-foot of water can be visualized as a football field one foot deep in water.
  • An acre-foot of water supplies the needs of two average Southland families in and around their homes for one year.

Reservoir Surface Area:

  • 4,500 acres
  • 4.5 miles long
  • More than 2 miles wide
  • 160-260 feet deep
  • Maximum elevation 1,756 feet above sea level


  • West dam: Earth/rock fill construction 285 feet high, 1.7 miles long (9,100 ft.) 1,200 feet wide at the base and 40 feet wide at the crest.
  • East dam: Earth/rock fill construction 185 feet high, 2 miles long (10,500 ft.) 800 feet wide at the base and 40 feet wide at the crest.
  • Saddle dam: Earth/rock fill construction 130 feet high, (above the lowest point on the ridgeline), 0.5 miles long (2,300 ft.), 720 feet wide at the base.
  • More than 110 million cubic yards of earth and rock will be required for the largest earth and rock fill project in the United States. Excavation began in 1995. Dam construction begins in late 1996.

Water Sources:

  • Colorado River Aqueduct delivered through the San Diego Canal into the reservoir forebay. Water is pumped from the forebay into the reservoir.
  • California State Water Project from Silverwood Lake into the reservoir by gravity, through a new 12-foot diameter, 45 mile Inland Feeder, connecting with the new 9 mile Eastside Pipeline.

Pumping Plant:

  • Twelve pumps at 5,000 horsepower each.
  • One 1,000 cubic feet per second hydraulic control structure at Colorado River Aqueduct.

Recreational Opportunities:

  • There will be a Bicycle trail all the way around the lake with several boat docks.
          *If your tired of peddling a ferry will pick you up and bring you back*
  • Hiking trails and Equestrian trails
  • Camping, picnicking, overlook, golfing
  • Boating, sailing, fishing
  • Special events area, separate swimming pools/lagoons
  • No body contact will be allowed in the reservoir
  • Limited types of boats will be allowed

About the Fishing

The original projected opening date for the sprawling new reservoir in western Riverside County -- Diamond Valley Reservoir -- was this year, but now the Metropolitan Water District is saying the facilities will not be open until March, 2003, when the marina and recreation areas will be completed.

With the lake 2/3s full and 140 feet deep in places that seems like a long wait to allow for shore fishing and perhaps some limited boat fishing access. The huge reservoir, which is located near Hemet, was created by building long dams at the mouths of two valleys that drain off the north end of Black Mountain. The dams block off the Diamond and Domenigoni valleys to create the largest reservoir in Southern California, one that will hold 800,000 acre feet of water when full. It is currently filled with about 570,000 acre feet.

The word is already starting to get out about the tremendous fishery that has been created at Diamond Valley (once called Domenigoni Reservoir and then Eastside Reservoir before the final name was bestowed). Mike Giusti, the Department of Fish and Game biologist on more-or-less permanent assignment as the Diamond Valley fishery and habitat specialist, has had generous MWD funding to create a model fishery at Diamond Valley. The lake has been planted with the purest strain Florida largemouth bass, Florida bluegill, redear, crappie, smallmouth bass, channel catfish, blue cats, and rainbow trout. Silverside minnows and shiners were added as forage for the gamefish, and the results so far have been pretty spectacular.

Before the lake started to fill, a rearing pond was built in the future lake bottom. Broodstock bass to eight pounds were released in the pond and there was a spawn of those fish in 1999. Later that year, as water was pumped into the new reservoir the lake level crested the pond and that year’s spawn of fish had the whole growing lake where they could feed. Those two-year-old fish are now in the 12- to 15-inch range and weigh from two to three pounds. For fish that size, they are chunks.

Giusti likes to point out that the Golden Ruler used by bass anglers to estimate weights would tell you that a 13-inch bass should weigh 1.1 pounds and a 15-inch fish should weigh around two pounds. And that is true at most places. At Diamond Valley, a 13-inch bass weighs right at two pounds and a 15-incher right at three pounds. The eight-pound broodstock bass that was in the pond was recaptured this year, and it weighed 12 pounds, putting on four pounds in just two years.

Giusti said the 2000 year class fish are all 10-inchers, and he estimates the bass population in Diamond Valley is around 300,000 fish already.

“The sampling I’ve done out there is unreal,” said Giusti, who has been taking scale samples from 25 bass per month to chart growth rates. “Four of us on the electro-fisher, which is not the best boat to be fishing from, boated 300 bass in 3 1/2 hours of fishing. Three casts in a row I caught two fish on a the same jerk bait.”

The first trout plants went in during November and December last year. These were subcatchable-sized rainbows. These small fish are classed as to how many of them it takes to weigh a pound. The stocks late last year consisted of six to 15 fish to the pound. By May this year, those trout were in the one to 1 1/2-pound range.

“That gives you some idea of the growth rates were going to see, at least initially,” said Giusti.

It sure would be nice to see the lake open to at least shore fishing this year. Giusti expects the two-year-old bass to be five-pounders by the end of the year. While regulations haven’t been adopted for the reservoir, Giusti is leaning toward a slot limit where two or three bass under 13 inches could be kept by anglers and one or two over 16 inches could be creeled. He’d like a zero limit on the smallmouth bass until they become established and regular limits on other species.

Last Update January  2007

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