SOUTH LAKE TAHOE (AP) — Conservationists at Lake Tahoe are suing over new regulatory changes they say will erode environmental protection of the mountain lake by failing to adequately monitor water quality, allowing for construction of bigger buildings near the shore and thousands of more housing units in the basin. The Sierra Club and Friends of the West Shore filed a lawsuit in U.S. District Court in Sacramento on Monday challenging rules the Tahoe Regional Planning Agency adopted in December for its new regional plan. The suit says the changes would allow local governments around the lake to adopt weakened pollution controls that don't meet minimum standards set by the bistate panel that Congress authorized in 1980.