Building embassies in Stirling Park will permanently damage the lake environment and limit the ability of Canberrans to use it in ways they may not yet appreciate, residents will tell a parliamentary committee on Friday.

The standing committee on the national capital and external territories will hear first-hand from residents who are opposed to siting a diplomatic enclave in Stirling Park.

The committee is investigating the management of the ACT's diplomatic estate after a row erupted over the proposal by the National Capital Authority for nine embassies at Stirling Park.

The residents say Stirling Park and its popular Stirling Ridge, even though owned by the authority, should be left as open space for all Canberra residents to enjoy.

Five new diplomatic missions are being established in Canberra and seven other nations want to build or lease missions.

John Wallington, co-founder of Balloon Aloft in Canberra, is calling for a long-term solution to siting embassies.

''The siting of embassies or residences in the [Stirling] park will damage forever the greater lake environment and its ability to be used and appreciated by Canberra residents for all time in ways we may not even yet appreciate,'' the Yarralumla resident says in his submission to the inquiry.

''There is a well-established precedent in O'Malley of not locating all diplomatic missions in the central Canberra area.

''The NCA is in a position to preserve irreplaceable land for future generations and solve the requirements for diplomatic land for all time.

''These options, however, require more planning, communication and possible expense than the short-term ad-hoc fix of a quick bite out of Stirling Park.

''The NCA would be commended if it fully embraced the long-term solution that would avoid the environmental, social and cultural damage that will result in the current proposal.

''If the NCA is not prepared to make that decision, it needs to be directed to do so.''

Member for Canberra Gai Brodtmann will use Friday's hearing to ask what is planned for the undeveloped land in Yarralumla held by countries with existing missions in O'Malley.

''Another issue I will be pursuing is how the planners got the current diplomatic estate of O'Malley so wrong, when 15 out of 19 sites set aside for missions can't be used,'' she told Fairfax Media.

''What long-term plan exists for the management of the diplomatic estates?

''The submissions underscore why this inquiry is so necessary, they underscore the need for a clear-eyed and long-term plan for the management of the diplomatic estates in Canberra.''

The Department of Foreign Affairs says nations establishing new embassies want high visibility for their missions and secure tenure.

The department says new missions should be established in diplomatic enclaves with easy access to Parliament House.

Four new embassies were established in Canberra in 2010 and 2011, and three last year. The Syrian mission closed last year.

Of the 99 diplomatic missions in Canberra, 52 are in the diplomatic estate - in Yarralumla, O'Malley and Deakin.

The committee has published the 15 submissions received and does not list a submission from the ACT government.

The NCA suggests a number of smaller diplomatic missions may be interested in leasing part of a designated diplomatic office building, possibly with shared services.

The Save Stirling Park group disputes the need for high-profile embassies and says some could be housed in commercial office space.

''Logical analysis indicated the claimed existing demand to build chanceries is exaggerated and future demand is overstated,'' the group says in its submission.