A public meeting will be held in Gloucester tomorrow as a prelude to a National Day of Action against coal seam gas (CSG) mining on Sunday, October 16, at the start of National Water Week.

Lock The Gate Alliance (LTGA) has endorsed 'Defend Our Water' as a key theme of the national day of action.

One of its partners, Barrington-Gloucester-Stroud Preservation Alliance, will meet at 7pm tomorrow at Gloucester Soldiers Club, and invites all concerned members of the public to attend.

Alliance members Michael and Julie McNamara feel so strongly about the issue that they are undertaking a speaking tour of NSW during August and September to promote the national day of action.

At tomorrow night's meeting Mr McNamara will outline the concerns about coal seam gas mining and plans for the National Day of Action incorporating Defend Our Water.

Rallies will be held simultaneously in capital cities and in rural and regional communities on October 16.

"The National Day of Action seeks to highlight the importance of water to the Australian community in a number of areas and the impact that CSG mining could have," Mr McNamara said.

"The issue of coal seam gas mining is one of the most important to confront local communities in many decades," he said.

"In the Gloucester-Stroud-Manning Valley it is no different."

"Local water supplies and water quality are under threat, as are significant local industries such as agriculture and tourism," Graeme Healy, from the Barrington-Gloucester-Stroud Preservation Alliance, said.

"Communities across the country will be asked to Defend Our Water in a protest against the potential impacts of coal seam gas mining on water quality and availability."

Mr McNamara said Defend Our Water focuses on the importance of good quality water for a range of community activities, particularly agricultural production.

"The quality of water also has grave implications for community and individual health," he said.

Lock The Gate Alliance is a national alliance of more than 90 community, industry and environmental groups and thousands of individuals who are concerned at the potential impact of coal seam gas mining on communities, the environment and existing industries.