Hi Alden, both the Lower and Upper Niagara river offer good fishing in the spring for Walleye and Trout. Make sure to check Ontario Fishing Regulations to ensure the fish you are targetting is open. Most anglers fish launch out of the Queenston boat launch on the Lower River. If they fish the Lower River from shore they fish at the boat launch, at Fort Old Fort Henry and the Whirlpool.
On the Upper River most people either launch at Chippewa, ON or in Fort Erie, ON. Both have public launches. Shore anglers have lot’s of options there from the Peace Bridge and at different access like the Fort Erie boat launch, and pier north of the railway bridge.