THE Detroit River exerts a powerful influence on Jimmy Schmidt's restaurant, the Rattlesnake Club.The river, turquoise and deep, is a magnet for the entire southeastern Michigan region. Its banks just upriver from downtown Detroit, long cordoned off for warehouses and chemical and manufacturing plants, are accessible again. Sturdy old brick buildings are being converted to smart corporate headquarters and condos. Scions of auto, chemical, and other Detroit industrial families are investing here, to orient the city again to its natural geographical base, the waterfront. Mr. Schmidt's restaurant is a party to this renaissance, but the big player is the river itself. It is a factor in Michigan's peninsular psychology; the state's water rim oddly links the state more to Canada and the great northern woods than to Ohio and Indiana beneath it. The lower peninsula was long cut off by land from the east by the great Maumee River swamp at the Lake Erie corner; the firm shore of Detroit, at the narrows of the flow of Great Lakes water toward the St. Lawrence, was a crucial tradi ng post in Indian days, and an industrial site subsequently, for the wood, ore, coal, and other resources from the Midwestern interior. Schmidt plays to this history. "The Rattlesnake is a modern American restaurant with Midwestern ingredients," he says. "Michigan has a bounty of native food products: morel and chanterelle mushrooms; blueberries, blackberries, raspberries; stone fruits like tart and sweet cherries, peaches. The state has a lot of antique apples: One place near Holland grows 200 varieties of apples, like Empires. There are lots of poultry and game birds toward the center and northwestern parts of the state. Pheasants and other game birds are hatched for release to the wild; farmers who raise them are allowed to keep a percentage of that stock for the commercial trade. They're good birds, and you don't have to pick the buckshot out of them. "The farmer's market exists at the Eastern Market nearby," Schmidt says. "You can buy everything there, from game birds and collard greens to homemade honey." "Pickerel" on the menu is actually yellow walleye pike, trucked down from Lake Superior and the Upper Peninsula, Schmidt explains. Others use a blue pike and call it "pickerel." Baked with a little paprika, the walleye is as succulent as trout but has fewer bones. The Great Lakes fishes are making a comeback - particularly the muskellunge, which fatten to enormous size on the littler fishes raised in hatcheries and then released to stock the waters. Fishermen trawl again for giant lake sturgeon, which ha ve returned to the river bottom to feed. Schmidt gets smoked lake trout from an Indian tribe in Wisconsin: The tribe's leaders call now and then (Schmidt can't call them), and offer so many pounds of freshly smoked fish, which he always accepts; free of fish and game laws, the Indians can fish any way and any time they want. Seafood comes from other parts of the country: North Atlantic fish from Boston, lobsters from Maine, crabs from Maryland and South Carolina, mahi-mahi from the Gulf of Mexico. This non-Midwest aquatic produce reflects the broader "American" aspect of the Rattlesnake's fare. Prickly pears, poblano peppers, blue corn, are from the Southwest. Ingredients like black walnuts and butternuts are links to Jimmy's home state of Illinois. He grew up in Champaign-Urbana, in a family that had helped clear the prairies and got into the lumber trade and farming. SCHMIDT studied electrical engineering at the University of Illinois nearby. On a trip to Avignon, France, he met Madeleine Kamman, the French-American cooking teacher and author. He followed her to Boston for chef's training; got a job at Detroit's former No. 1 restaurant, the London Chop House; went to Denver as the chef of that city's famous Rattlesnake Club; and after a short stint in Washington, D.C., returned to Detroit to launch his own place in 1988. Each of his career steps has gained him critic al praise. Schmidt realized in 1980 he would never become both a great engineer and a great chef, so he gave up engineering. But his interrupted study of engineering has been of use: "There is a correspondence between electrical engineering and cooking - conductivity, for instance, whether electrical or thermal," he explains. "And the analytical chemistry I took is most helpful in dealing with food." Schmidt's cooking is rooted in basic French techniques that he learned from Ms. Kamman. He has spent more than a decade building his own repertoire of recipes, which reflect the modern American emphasis on fresh ingredients and inventiveness. He is currently touring to promote his first book, "Cooking for all Seasons" (Macmillan; $24.95, cloth). 'I'm a very organized cook," Schmidt says of his approach to the kitchen, again crediting his engineering background. "And I'm a very organized manager." He'd better be organized. Schmidt has a $2.6 million loan from Barclay's of London to finance the Rattlesnake. He runs another restaurant, Tres Vite, in the city's downtown, and two others are under development - Cocina del Sol, a Southwestern-style restaurant in nearby Southfield, and Stelline, an Italian-Mediterranean restaurant in the suburb of Birmingham. On top of this he manages the food operation for the River Place Inn, a classy new waterfront hotel near the Rattlesnake. "I lay out all the kitchens," Schmidt says of all this enterprise. He also has the help of a chief financial officer. "It's a business," Schmidt says of the project. "I put together the p&l's [profit and loss statements], and the cost of capital." He likes to talk about the "cost of funds," rates like "prime plus one-quarter.I can borrow for 1 day up to 365 days," he enthuses, "and keep rolling it over." "A restaurant is business, theater, schmooze, and food," Schmidt says. "Detroit is not a destination city, like L.A. or San Francisco, so our permanent customer base is very important. For return customers, being recognized is more important than any other factor. Second is the food, third is price, and fourth is sanitation." The Rattlesnake is a large, open-feeling restaurant in a former Parke-Davis Company building. The maple chairs were designed by Eero Saarinen for the Kingswood School at nearby Cranbrook Academy. The wood trim above the floor is American cherry; the floor wood is Brazilian cherry, which is harder and can take the traffic. The overall concept is that of Frank Lloyd Wright's architecture, which sought to reduce the sense of separation between an interior and the world outside. In this case, the world outside is dominated by the Detroit River. Turquoise accents from the river are caught in the decor. Schmidt has added paintings by Frank Stella and Jasper Johns. The river even has influenced the floor plan: The city building code requires buildings to maintain lines parallel to the river, regardless of the angle of approaching streets. So all the "right" angles in the Rattlesnake building are either 93 degrees or 87 degrees - quite an engineering challenge, Schmidt observes. The style of Schmidt's cooking is modern. Overall, he says, the evolution of cooking today is away from "overworked" (by which he means "overhandled"), rich (butter and cream sauces) food to good, solid, "real ingredients you know, chickens that taste like chicken prepared with creativity and ingenuity." What American restaurants does Schmidt see as setting the pace? Campanile, Patina, and Citrus in Los Angeles; Bouley, Gotham, Prefix, and the Mesa Grill in New York; Cypress Club and Postria in San Francisco; and the Frontera Grill in Chicago.