The O’Neill Forebay, the equalizing basin for the massive San Luis Reservoir looming just above it, has been popular with fly anglers pursuing its striped bass for decades. However, it’s not the same lake it was when I first started fishing it in the late 1960s. Its aquatic composition has changed dramatically over the years, particularly regarding weed infestation by Egeria densa, a common aquarium weed that was likely introduced to the Sacramento–San Joaquin River Delta by someone dumping an aquarium into a roadside slough. This incredibly fast-growing weed spreads like wildfire, covering acres of shallow-water flats and spreading outward for many feet along deeper shorelines and rock edges such as the rock-lined dam along the northern and eastern sides of the forebay. Fortunately, this weed doesn’t like water deeper than about ten feet or strong currents. Like the forebay’s striped bass, largemouth bass, and baitfish, Egeria and another long, stringy weed, the name of which I don’t know were introduced via the Highline and Delta Mendota Canals, the “umbilical cords” connecting the Delta with the O’Neill Forebay and ultimately with San Luis Reservoir and the California Aqueduct.
In years past, before the weed infestation, the many acres of shallow, open flats making up the southern side of the forebay from the Highway 156 channel to the Medeiros flats were very productive. Ditto for the f lats bordering the western and northwestern shoreline. Fly anglers would drift their watercraft across the flats in water ranging in depths from around 3 to 8 feet, blind casting shooting heads of slower-sinking densities to schools or pods of stripers foraging on threadfin shad or Wakasagi minnows. With notable exceptions, those flats are now almost impossible to fish from a boat, since there is very little open water.
Also productive was casting a fly right to the rocks of the dam, impossible now because of weeds growing out from the rocks 10 or more feet to water depths of as much as 10 feet.
Not only have the flats become almost impossible to fish because of dense weed, so have the various deeper channels around the PG&E tower islands located on the northwestern end of the flats and the Highway 152 channel, as we call it. While this all may sound very discouraging, fly fishing the O’Neill Forebay today for its landlocked striped bass is still very rewarding and incredibly fun for those in the know who understand its nuances — how, when, and where to fish this incredible man-made lake, adjusting to the changes that have occurred over the years.
Rods and Reels
If you fly fish for larger trout with streamers and bucktails or for species such as largemouth bass, smallmouth bass, white bass, and so on, you likely already have the right gear for the spunky forebay stripers. Most forebay veterans fish with rods ranging in size from 6-weights to 8-weights, with a 7-weight being an almost perfect choice, light enough to get the best out of these fish, but with backbone enough to handle a surprise Big Moe — and trust me, that happens often enough that you want to be able to handle one. I have all three rod sizes in my skiff and fish them according not only to fish size, but to conditions and occasions, such as when I need to combat wind or hurl bigger, heavier flies and poppers.
Reels need not be expensive saltwater models, but they should have a decent drag, and those with palming rims are preferable to help slow down and control the run of a larger fish. This said, most of the fish you hook, even those in the three-to-four-pound range, will be handstripped to net or hand. They will put a serious bend in your rod and a cramp in your forearm if you land many in a few hours of hot fishing. Finger stripping guards are required.
A word of caution here: in the late summer and early fall, the water temperature can reach well into the 70s, and while these strong fish will still put up a fantastic fight for their size, if you take too long to land one, it may die from overexertion and lack of oxygen or from lactic acid overload. Of the hundreds of fish my regular fishing partner, Vaughn Willette, and I landed from this spring through late summer, only two fish succumbed once the water temperature exceeded 70 degrees. So if you are a catch-and-release angler, keep this in mind and try to land your fish quickly.
Fly Lines and Leaders
When fly fishing for stripers at the O’Neill Forebay, you will usually want to cast large f lies a long way, using a sinking line that will quickly drop down to where the fish are holding. A lot of older-generation forebay anglers still prefer homemade lead-core shooting heads ranging in length from 25 to 30 feet, looped to a shooting line of 20-to25-pound-test mono such as Amnesia, material that can be easily stretched to remove coils. However, many also prefer level floating shooting lines .030 to .034 inches in diameter with braided mono or welded attaching loops. A level size 2 floater likewise works well for a shooting line. (A number of line companies offer small-diameter level shooting lines that come with welded loops.) Some fly fishers like to make heads from tungsten line, T-11 and T-14, in similar lengths, using similar shooting lines.
Popular, too, are integrated-head “custom cut” lines and “custom tips,” such as those offered by RIO and Scientific Anglers, which allow the fly fisher to cut the head length to match his or her rod. The custom-cut lines I use at the forebay have a 36-foot or so head of either T-11 or T-14. For a 7-weight rod, I cut the T-11 to 30 feet and the T-14 to 28 feet. I also use a 6-weight rod with a T-14 head cut to 25 feet, joined to a .030-inch-diameter floating running line. It casts large flies easily 90 feet or more and is a blast on fish ranging from 14 inches to three or four pounds, although I’ve landed much larger fish on the 6-weight, matched to a quality reel with ample drag and a palming rim.
Leaders needn’t be complicated: a straight length of 20-pound mono 8 feet long is perfect. I like Maxima, but you can use whatever your favorite mono leader material is. A three-turn Surgeon’s Loop is perfect for looping the leader to the loop on the line end, and it’s very strong. I use the Kreh Nonslip Mono Loop to attach the fly. This knot also is very strong, and the loop allows the fly maximum action — dipping and diving, darting side to side.
Flies
As I mentioned earlier, threadfin shad and Wakasagi minnows in various sizes are the most prominent of the bait species on which the stripers and largemouth bass feed. They also eat damselfly nymphs, snails, clams, crayfish, and a host of other things that keep forebay stripers fat, healthy, scrappy, and thick across the shoulders.
Many times, especially in the weed beds or along their edges, you’ll see swirls and rises almost identical to rises and boils made by trout eating swimming nymphs. Many anglers new to the lake mistake these swirls and boils for stripers eating baitfish. They are stripers eating damselfly nymphs, and it pays to carry a few damselfly nymphs in dark colors, size 8 to 4. You’ll be amazed at how many stripers you’ll catch on swimming nymphs. When they are targeting bugs, they can get very selective, just like trout, and will usually refuse a baitfish fly.
Bugs notwithstanding, you’ll still catch a whole lot more fish using baitfish flies in sizes from 1/0 to 3/0, with the smaller f lies often producing best, because the shad are small in the summer and fall. The most popular style of baitfish-simulating fly is the Jig-Hook Flashtail Minnow on a 1/0 hook, about three to three and a half inches long from the nose to the end of the flashtail, in (from bottom to top) white/yellow/ brown. White/yellow/chartreuse can also be good at times. Lee Haskin’s San Luis Smelt is also a killer at times. Small standard Clouser Minnows also work well when the baitfish are small. You’ll want to tie or buy these flies on strong hooks, though, because even big fish eat small baitfish and flies.
An example of that surprise occurred in September 2020 when Vaughn and I were working the Highway 156 channel weed edge in about twelve feet of water. We were catching small-to-medium all-purpose fish when Vaughn got slammed hard by a fish that had him into his backing almost instantly. After a helluva battle, with the fish first trying to wrap the line in the weeds and then surging to deep water, Vaughn finally got it close enough for a look, and we saw that it was a big fish. I grabbed the 60-pound BogaGrip landing scale, and when the fish finally was on its side, I lipped it, revived it, and then lifted it for weighing and a photo before releasing it — a gorgeous 25-pounder. It swam off and down no worse for wear.
The world record landlocked (lake) striper on a fly was another huge surprise package landed on September 17, 1989, by San Luis and O’Neill Forebay veteran Al Whitehurst. It was a pig of a striper weighing 54-1/2 pounds. Al caught this fish on a yellow Lefty’s Deceiver in a channel near the west tower island, fishing from a float tube. No one has topped that fish since, fishing flies, gear, or bait.
It pays to have some small poppers simulating top-water baitfish, such as the Ron Dong Crease fly (RDCF) in size 2, about an inch and a half long, for the times in the late summer and fall when the stripers blow up on small shad minnows. I have a relatively stiff 7-weight rod lined with an aggressively tapered floater, Quigley twisted leader, and a 20-pound tippet tied to a small RDCF always at the ready in case a top-water opportunity presents itself. It’s a hoot when it does.
Boats and Other Watercraft
You see anglers of all kinds fishing the O’Neill Forebay from all sorts of boats and other watercraft, from float tubes to pontoon boats and kayaks, and they all catch fish if they are doing it right. However, an important factor to consider is the wind, which can come up quickly and is strong enough to produce sizable whitecaps. I suggest fishing from a skiff at least 16 feet in length, one that can handle some rough water and is easily maneuvered with an electric trolling motor. I fish from an 18-foot Western Eagle center-console skiff, for example.
Float tubers do well, as do those fishing from pontoon boats. Inflatable pontoon boats handle very rough water surprisingly well. Most of today’s personal inflatable pontoon boats will accept an electric trolling motor, which allows the angler to cover a lot of water.
All hard-hull boats, including kayaks and similar craft, have to pass a quagga mussel inspection before being allowed on the lake. The inspection is done when you check in at the San Luis Creek entrance kiosk. The park ranger will do the inspection. The cost for the inspection, parking, and launching is $17. Boats upon leaving will be banded, so no inspection will be required as long as the band hasn’t been broken when returning to the lake again. Float tubes and personal inflatable pontoon boats do not have to be inspected. This is a recent change in policy regarding inflatables.
Finding High-Percentage Spots
The O’Neill Forebay has a shoreline approximately thirteen miles long, so it’s not a big lake and can be covered quickly with a boat with a decent motor. Finding the high-percentage spots (the HPSs), which is what I call the most productive areas, is part of the equation for successfully fly fishing the Forebay. That requires good electronics. A fish finder with both down-scanning and side-scanning capabilities is a huge boon, whether fishing from a conventional boat or an inflatable of some kind. Two of the best and most popular models for boats are the Lowrance and the Humminbird units, which not only have great down and side imaging, but also incorporate an excellent GPS feature that lets you navigate the lake even in the densest winter fog and shows you bottom features such as humps, flats, and holes. When you locate one of these potentially productive spots, if you have a GPS, you can mark it on the graph and easily return to it anytime if it proves to be an HPS. (If you lack a GPS, note landmarks so you can find the HPS again.) Portable battery-powered units that feature down and side scanning are also available for tubers, pontoon boaters, and kayakers. I have one made by Humminbird, but of course, there are other brands available.
Catching the Stripers
Because the weeds now define the angling environment at the O’Neill Forebay, to catch fish, you need to work the weed edges, both along the rocks of the dam and along the eastern side of the Highway 156 channel, as well as along the entire edge of the flats weeds where they drop off abruptly from shallow to deep water. Work from the tower f lats all the way to the Medeiros flats where they meet the buoy line at the California Aqueduct outflow.
A productive approach to working the Highway 156 channel is to start at the bridge buoy line. A favorite tactic of mine is to position the bow of the boat almost on the weed edge with the boat perpendicular to it and cast and retrieve the fly parallel and close to the edge. You cover a lot of water this way, especially if two anglers are fishing from the same skiff. This approach is particularly effective when plying the ribbon of weeds along the rock walls of the dam. Another favorite tactic is to position the boat right on the drop-off of the weed line in about twelve or so feet of water and move along slowly with the electric motor, casting out to deep water, counting the line down about twenty counts or so, and stripping the fly uphill.
The most productive areas of the dam rock wall seem to be about halfway up the wall to the north from the bend and all the way along the eastern run to the California Aqueduct outflow buoy line. Of course, there are HPSs all along the rock wall, especially where the bottom humps up. Stripers love edges, humps, and shoals, because they can trap baitfish against them. The canal inlets at the northeastern and northwestern ends of the lake can also be productive at times, so it pays to make the run up for a look.
Sometimes, though, the fish are not to be found along classic weed edges and for whatever reason school up and roam the open waters of the lake — the middle ground between the boat ramp and the rock dam in about twenty-five feet of water. Here’s where fish finders really come into play, since you just motor around with your main engine or electric motor, watching the screen until you see fish marks — ideally, a lot of them. When you do, note the depth at which they are holding and fish for them accordingly. Most of the time, they will be halfway down or deeper. Wherever you are fishing, always keep and eye out for fish busting baitfish on the surface and have a rod set up with a floating line and popper. Get to them fast, but don’t run over them, putting them down.
Retrieves
You’ll see all sorts of retrieve styles being used by anglers on the forebay, but I like a varied retrieve, with a full arm pull a couple of times, shortened to half arm extensions and then to several quick strips of a foot or less, with at least three five-second stop and drops, letting the fly fall before repeating the process. Always be ready for a fish to eat on the sink, and if you lose contact with the fly, set the hook using a hard pull with the line hand and a hard sweep of the rod low and to the side. Strip strikes alone don’t move enough line to stick the fish when they eat coming at you. Always retrieve the fly until the leader hits the rod tip — stripers are notorious for following the fly and eating it at the last second.
The Best Days to Fish
The best days to fish are days when the wind is going to be down or very light. Many of us plan our days based on the wind predictions made by an online wind prediction site called Windfinder, https://www.windfinder.com/forecast/san_luis_ reservoir. Pick the day or days with the lightest predicted wind. The predictions aren’t perfect, but will give you a good idea if you’ll be able to fish safely or not.
The striper season at the O’Neill Forebay is pretty long, beginning in the spring and running all the way through the winter, especially if the winters are mild. I like the early summer through late fall, with September being one of my favorite months.
Keep Tuned in to the Action
To stay current on O’Neill Forebay information (and also information about San Luis Reservoir itself), fishing reports, and more, go to my website bulletin board, www.danblanton.com/ bulletin.php, and also to veteran O’Neill Forebay and San Luis fly fisher Meng Syn’s blog, www.mengsyn.com.
If You Go…
The O’Neill Forebay is part of the San Luis Reservor State Recreation Area. You can access a five-page brochure for the area, which includes rules and a useful map, by scanning the QR code below with your smart phone.
