They are formal regulations and are enforced.

http://www.algonquinpark.on.ca

Motor Restrictions in Algonquin ParkMotor boats are not permitted on most Algonquin lakes. Power boat means a boat that is propelled by electric, gasoline, oil or steam motive power.There are four groups of exceptions listed below. For lake locations please see the Canoe Routes Map of Algonquin Park.

(a) Motors of unlimited horsepower may be used on:

• Galeairy Lake
• Lake Opeongo

(b) Motors of 20 horsepower or less may be used on:

• Bonita Lake
• Cache Lake
• Canoe Lake
• Cedar Lake
• Kingscote Lake
• Kioshkokwi Lake
• Little Cauchon Lake
• Rock Lake
• Smoke Lake
• Source Lake
• Tanamakoon Lake
• Tea Lake
• Lake of Two Rivers
• Whitefish Lake

(c) Motors of 10 horsepower or less may be used on:

• Cauchon Lake
• Cauliflower Lake
• Grand Lake
• Joe Lake
• Little Joe Lake
• Madawaska Lake
• Manitou Lake
• North Tea Lake
• Radiant Lake
• Rain Lake
• Tepee Lake
• Lake Travers

(d) Motors of 6 horsepower or less may be used, except from the last Friday in June to the first Monday in September inclusive, on:

• Big Crow Lake
• Hogan Lake
• Lake La Muir
• Proulx Lake
• Little Crow Lake
• White Partridge Lake

https://www.ontario.ca/laws/regulation/900952

R.R.O. 1990, Reg. 952: GENERAL under Provincial Parks Act, R.S.O. 1990, c. P.34
27. (1) No person shall operate a power boat except for the purpose of park management in,
(a) Arrowhead Provincial Park;
(b) Algonquin Provincial Park;
(c) Awenda Provincial Park on Second Lake;
(d) Bon Echo Provincial Park;
(e) Charleston Lake Provincial Park on that part of Charleston Lake known as Slim Bay, Duck Bay or on the southwest part of Running Bay as demarcated by buoy-type signs;
(f) Dividing Lake Provincial Park
(g) Earl Rowe Provincial Park
(h) Esker Lakes Provincial Park
(i) Five Mile Lake Provincial Park on Red Bark Lake or White Bark Lake
(j) Frontenac Provincial Park;
(k) Greenwater Provincial Park
(l) Grundy Lake Provincial Park;
(m) Hardy Lake Provincial Park;
(n) Ivanhoe Lake Provincial Park on Saw Lake, Lea Lake or Hall Lake;
(o) Kesagami Provincial Park;
(p) Kettle Lakes Provincial Park except on Hughes Lake
(q) Killarney Provincial Park;
(r) Lake on the Mountain Provincial Park Picnic Grounds
(s) Lake Superior Provincial Park
(t) Mississagi Provincial Park on Christman Lake
(u) Murphy’s Point Provincial Park on Hogg Lake, Loon Lake or Black Creek
(v) Nagagamasis Provincial Park on Park Lake
(w) Polar Bear Provincial Park
(x) Quetico Provincial Park
(y) Samuel de Champlain Provincial Park on Long Lake;
(z) Silent Lake Provincial Park
(za) The Pinery Provincial Park on that part of the Old Asauble Channel located within the limits of lots 9 to 31 inclusive, Lake Range West Concession, Bosanquet Township;
or (zb) Wakami Lake Provincial Park on Imakaw Lake.

R.R.O. 1990, Reg. 952, s. 27 (1);
O. Reg. 767/94, s. 7 (1).
(2) Despite subsection (1),
(a) in Algonquin Provincial Park, a person may operate a power boat,
(i) on Galeairy Lake and Opeongo Lake,
(ii) with an engine rating not exceeding 20 horsepower on Bonita Lake, Cache Lake, Canoe Lake, Cedar Lake, Kingscote Lake, Kioshkokwi Lake, Lake of Two Rivers, Little Cauchon Lake, Rock Lake, Smoke Lake, Source Lake, Tanamakoon Lake, Tea Lake or Whitefish Lake,
(iii) with an engine rating not exceeding 10 horsepower on Cauchon Lake, Cauliflower Lake, Grand Lake, Joe Lake, Manitou Lake (formerly called Wilkes Lake), Madawaska Lake, Lake Traverse, Little Joe Lake, North Tea Lake, Radiant Lake, Rain Lake or Tepee Lake, and
(iv) with an engine rating not exceeding six horsepower on Big Crow Lake, Crow River from Proulx Lake to Little Crow Lake, Hogan Lake, Lake LaMuir, Little Crow Lake, Proulx Lake or White Partridge Lake.  

Agree 100% with the others ... someone will report you faster that a fly on sh ... well you know ...