are the results of nitrogen carried into the gulf from surrounding agricultural land, with almost 90% coming from the dairy-farming runoff into the Firth of Thames. Other exploitation such as the dredging of the mussel beds of the Firth of Thames, reaching its height in 1961 with an estimated 15 million mussels taken (shortly before collapse of the industry) have led to damage which has not been recovered from forty years later, possibly due to the dredging having destroyed the seafloor, and sediment drainage from the agriculture in the Firth of Thames affecting the mussel's viability. Numerous beaches dot the shores of the gulf, many of them well known for swimming and surfing. Although environmental problems exist around urban areas, with 14 out of 52 beaches in the Auckland Region at least occasionally showing unsafe pollution levels (mostly because of untreated sewage) for bathing, environmental groups are working to clean the beaches and restore their vitality. Marine Park Legal establishment Sections 7 and 8 of the Hauraki Gulf Marine Park Act 2000 state: 7 Recognition of national significance of Hauraki Gulf (1) The interrelationship between the Hauraki Gulf, its islands, and catchments and the ability of that interrelationship to sustain the life-supporting capacity of the environment of the Hauraki Gulf and its islands are matters of national significance. (2) The life-supporting capacity of the environment of the Gulf and its islands includes the capacity— (a) to provide for— (i) the historic, traditional, cultural, and spiritual relationship of the tangata whenua of the Gulf with the Gulf and its islands; and (ii) the social, economic, recreational, and cultural well-being of people and communities: (b) to use the resources of the Gulf by the people and communities of the Gulf and New Zealand for economic activities and recreation: (c) to maintain the soil, air, water, and ecosystems of the Gulf. 8 Management of Hauraki Gulf To recognise the national significance of the Hauraki Gulf, its islands, and catchments, the objectives of the management of the Hauraki Gulf, its islands, and catchments are— (a) the protection and, where appropriate, the enhancement of the life-supporting capacity of the environment of the Hauraki Gulf, its islands, and catchments: (b) the protection and, where appropriate, the enhancement of the natural, historic, and physical resources of the Hauraki Gulf, its islands, and catchments: (c) the protection and, where appropriate, the enhancement of those natural, historic, and physical