Apply phosphorous-free fertilizer. It's the law in Minnesota, unless you are fertilizing new lawn or a soil test indicates a need for phosphorous. Look at the three numbers on the fertilizer bag (10-0-10). The middle number (phosphorous) should be "0".
If fertilizer does not contain pesticides, it can go in the trash if it is dry/granular/powder or down the drain into a sanitary system if it is a liquid. If you are unsure whether the fertilizer contains pesticides, bring it to a household hazardous waste collection site for free.
Leave grass clippings on the lawn to reduce the need for fertilizer application during the growing season.
Sweep up applied fertilizer from driveways and sidewalks, so it doesn't run into storm sewers and contaminate nearby lakes and ponds.