A dispute between Arkansas and Oklahoma over water quality standards has some environmentalists upset at the Federal Environmental Protection Agency. They`re questioning whether the agency should be mediating the dispute instead of enforcing the law. Tulsa attorney Chuck Shipley told the E-P-A that Oklahoma residents are tired of waiting. Shipley and others are considering litigation to resolve the issue. An E-P-A spokesman says the agency is continuing to work toward a compromise. Arkansas regulators and the poultry industry protested the plan for rivers that start in Arkansas and flow into Oklahoma. Oklahoma wants Arkansas to ensure waterways flowing west have less phosphorous. Arkansas officials argue the phosphorus standard would curtail economic development in Northwest Arkansas.