Today hydroseeding is called for in areas where soil has been disturbed. It's an attempt to prevent erosion and establish new vegetation and, in many cases, is a response to government regulations preventing sediment from flowing from a disturbed site into other areas, such as storm drains and waterways. In hydroseeding, seed mixtures combined with water are hydraulically applied to soil. The mixtures include the seed appropriate to the soil and/or weather conditions, such as warm- or cool-season grass seed, and can include such amendments as fertilizers, wood-fiber mulch, and tackifier, all of which help hold down the soil while plants become established. Water retention, dispersing characteristics, and mixing ability are prime factors to consider when choosing the appropriate amendments. The client, job specifications, weather conditions affecting the area, germination rate, and susceptibility of the soil to erosion often dictate seed use and soil amendments.