The feud is over between the Hatfields and the McCoys -- known locally as the National Aquarium in Baltimore and the Power Plant.

"Peace has broken out in the Inner Harbor," Mayor Kurt L. Schmoke marveled last month, after the Cordish Company, the Power Plant's owner, decided not to park a floating Bubba Gump Shrimp Co. Restaurant in the inlet between Pier 4 and the aquarium's Pier 3.

But another development is now likely to test the peace -- and the outcome could dramatically alter the downtown skyline.

This spring, a Cordish affiliate negotiated a lease that allows it to build an office and retail complex that could rise up to 135 feet above wharf level -- the equivalent of 13 stories -- on city-owned land on Pier 4, between the Power Plant's entertainment/office complex and the aquarium's Marine Mammal Pavilion.

It would be one of the taller buildings on the water's edge, so large it would threaten to overwhelm the fragile Inner Harbor basin -- the source of so much of the city's appeal.

By allowing a 135-foot-tall building to rise south of the Power Plant, the city would be turning Pier 4 into a nearly solid wall that would divide the Inner Harbor basin from the land east of it.

The basin is already walled off to some extent by Scarlett Place and the Eastern Avenue Pumping Station along President Street, but for those looking eastward from the Harborplace pavilions, this new building would close it in even more.

From an urban design standpoint, it's a more damaging idea than last year's controversial shrimp boat. In effect, it would make the Inner Harbor seem two blocks smaller and more compartmentalized than it is today: The Inner Puddle.

In return, the city wouldn't gain one cent more in leasing revenues than it earns at present under the short-sighted agreement city officials negotiated with the developer. The lease deal could be seen as a reward for the ingenuity and risk-taking of the Cordish team, which has unquestionably succeeded in bringing life and activity to the long-dormant Power Plant. But it also raises questions about the future development of the Inner Harbor, particularly the narrow finger piers that jut into the water.

The city is eager for additional development, but is this the proper location for such a large building? Can the pier handle the additional pedestrian and vehicular traffic it would generate? How would it affect the expansion plans of the aquarium, which wants to build a river otter exhibit on the north side of the Marine Mammal Pavilion?

There comes a point when developers can try to cram too much into any one area -- and this may be it for the piers.

The new development would rise in place of the Chart House restaurant, which opened in the late 1970s inside a converted warehouse on Pier 4. The Cordish Company plans to raze the existing restaurant and build a much larger structure containing retail and restaurant space at wharf level -- including a new Chart House -- and office space above. The city would continue to own the land underneath.

According to an "amended and restated" lease approved April 21 by Baltimore's Board of Estimates, the replacement building could have a "total height" of 135 feet above the harbor promenade plus another 45 feet of "mechanical penthouses" and other "architectural treatments." That would put its highest point at 180 feet.

Part of the unprecedented nature of the Power Plant annex is that city officials approved the dimensions of the replacement project without knowing exactly what it would look like. This is different from most waterfront projects, which typically win approval only after they've been designed and thoroughly scrutinized. (A notable exception was Bubba Gump, which also negotiated a lease before any designs were developed.)

Cordish representatives are scheduled to present preliminary plans for the project this week to Baltimore's Design Advisory Panel, which reviews designs for new buildings planned throughout the city.

Allison Parker, a Cordish spokeswoman, said company executives don't want to release any images before the design panel meets. She also declined to say who the architect would be, but others familiar with the project say Cordish has been working with John Pickard Architects of New Haven, Conn., whose principal is a former employee of the noted designer Cesar Pelli.

Although the plans are at a preliminary stage, the developer's approach is suggested by a sketch filed with the city as part of the amended lease agreement. The sketch was submitted to indicate where signs could be placed on the exterior of the building, but it also shows how large it might be in relation to its neighbors.

The drawing shows a building that appears to rise about eight stories, with retail and restaurant space at wharf level and offices above. The lower levels are clad in masonry, like the adjacent Power Plant. The top is clad in glass, like many of the office towers in the central business district. There's some kind of spire or pylon at the top.

With the surface details still subject to change, the most telling feature of the proposed building is its mass. This is not a tall and slender tower like the World Trade Center. It's more like one of the shoe box-shaped buildings that form a frame around the harbor, along Pratt and Light streets.

The Board of Estimates approval of plans for a pier building of this size and shape raises questions about the city's willingness to adhere to planning concepts that have guided Inner Harbor development since the early 1970s.

In general, the city has permitted low buildings along the shoreline and set taller buildings farther back from the water's edge. The peaked roofs of the Harborplace pavilions, for example, could not be taller than the bowsprit of the USS Constellation. New buildings on the piers were treated as sculptural objects designed to accommodate one-of-a-kind uses, such as the aquarium and the Pier 6 Concert Pavilion.

In recent years there have been more and more exceptions to these rules. The Wyndham International Hotel is an example of a tall building allowed near the shoreline on land where a tall building was never meant to go. Columbus Center is part sculptural object and part generic shoe box.

In concept, the Power Plant annex is essentially a new building type for the Inner Harbor. It's not a sculptural object. It has a foreground location, but a background shape. It may be replacing the Chart House, but it seems to be a case of the city entering uncharted territory and making up the rules as it goes along.

The most distressing aspect of this design approach is the extent to which the Power Plant annex could adversely affect the way people experience the Inner Harbor. The piers are pleasant to stroll along now because there is ample open space between large buildings. By closing the gap in the middle of Pier 4, the Power Plant annex could ruin that ambience and sense of freedom. It also would cut off views of harbor attractions east of Pier 4, at a time when the city has been trying to get more people to walk eastward.

In addition to the wall formed by the building itself, the plan is likely to change the way people move around the finger piers. As part of the lease amendment, the city agreed to take stretches of public land and turn them over to the private development. It is also contemplating construction of a bridge that would enable people to drive cars from Pier 5 to Pier 4.

The introduction of more cars from the east would be another significant change to the waterfront. The Inner Harbor master plan was designed to minimize auto traffic. Over time, as the piers have become intensely developed, more and more cars have been allowed in areas where they weren't previously. A vehicular bridge linking Piers 5 and 4 could further limit the areas where pedestrians rule.

Another concern is the impact this building could have on the aquarium's expansion plans for Pier 4. Directors have been talking about building an outdoor habitat for river otters as a frontispiece for the Marine Mammal Pavilion. The power plant annex could make that sort of free exhibit more difficult to design and maintain -- not to mention less hospitable for the river otters.

Perhaps all these issues can be resolved. The city lease spells out the maximum amount of space that can be built on Pier 4. There is plenty of leeway in the guidelines for the developers to construct less than the maximum. And even though lease amendments have been approved, the Inner Harbor renewal area legislation still gives city officials wide latitude to accept or reject building designs on aesthetic grounds.

At this stage, the proposed building appears to be too big to fit comfortably into a location that wasn't targeted for intensive development. It's not the Cordish Company's fault for trying to get the best possible real estate deal from the city. But the city needs to be equally vigilant about preventing the Inner Harbor from becoming too cluttered.